RARE DISEASE
Pseudoachondroplasia
Pseudoachondroplasia
Pseudoachondroplasia
Synonyms: Pseudoachondroplastic dysplasia, Pseudoachondroplastic spondyloepiphyseal dysplasia
Synonyms: Pseudoachondroplastic dysplasia, Pseudoachondroplastic spondyloepiphyseal dysplasia
Synonyms: Pseudoachondroplastic dysplasia, Pseudoachondroplastic spondyloepiphyseal dysplasia
Drug discovery
0
drugs
With orphan designations
Overview
Pseudoachondroplasia is an autosomal dominant skeletal dysplasia caused by mutations in the COMP gene, leading to impaired cartilage oligomeric matrix protein function. It manifests in early childhood with disproportionate short stature (adult height: 116–120 cm), joint hypermobility, premature osteoarthritis, and skeletal deformities (e.g., windswept knees, scoliosis). Diagnosis combines clinical evaluation, radiographic findings (metaphyseal/epiphyseal irregularities, cervical instability), and genetic testing. Management focuses on orthopedic interventions, physical therapy, and surveillance for spinal/cervical complications [1][3][6][12].
Therapies
Orthopedic surgery: Osteotomies for limb deformity, spinal fusion for scoliosis/kyphosis, and joint replacements for severe arthritis [1][3][8]
Growth modulation: Guided growth techniques (e.g., hemi-epiphysiodesis) and selective limb lengthening [8][13]
Supportive care: Physical therapy, pain management, and cervical spine surveillance to prevent neurological complications [5][11][18]
Categories: rare bone diseases, rare developmental anomalies during embryogenesis, rare genetic diseases
Research Papers
53 drug discovery papers about Pseudoachondroplasia, with 1 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
53 drug discovery papers about Pseudoachondroplasia, with 1 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
categories:
Small molecules
small molecules
2025-04-28 | CurQ+ With Resveratrol Diminish Joint Pain in a Child With Pseudoachondroplasia: A Case Report.
This case report details the successful use of over-the-counter resveratrol and CurQ+ in a five-year-old with pseudoachondroplasia (PSACH), a severe dwarfing condition caused by mutations in cartilage oligomeric matrix protein (COMP). Disproportionate short stature, abnormal joints, joint deformities, and pain starting in early childhood are characteristic findings. Adult treatments include non-steroidal anti-inflammatory drugs (NSAIDs) and joint replacement to manage joint pain. Childhood pain goes largely untreated given the concern of daily use of NSAIDs in the very young. Recently, resveratrol has been shown to reduce pain and CurQ+ improves growth in a mouse model of PSACH. The use of these over-the-counter supplements has been adopted by some families with PSACH children. One such case in this report has a daily intake of resveratrol and CurQ+ at 125 mg of trans-resveratrol and 0.66 g, respectively, in the 16.6 kg child. This resulted in a dosage of 7.6 mg/kg of resveratrol and 40 mg/kg of CurQ+ daily. To date, no side effects from CurQ+ and resveratrol were reported in the child. Pain made walking to school very difficult (600 m) prior to the use of supplements and now the child walks to school without assistance or complaint.
2024-01-27 | Curcumin and Resveratrol: Nutraceuticals with so Much Potential for Pseudoachondroplasia and Other ER-Stress Conditions
Natural products with health benefits, nutraceuticals, have shown considerable promise in many studies; however, this potential has yet to translate into widespread clinical use for any condition. Notably, many drugs currently on the market, including the first analgesic aspirin, are derived from plant extracts, emphasizing the historical significance of natural products in drug development. Curcumin and resveratrol, well-studied nutraceuticals, have excellent safety profiles with relatively mild side effects. Their long history of safe use and the natural origins of numerous drugs contrast with the unfavorable reputation associated with nutraceuticals. This review aims to explore the nutraceutical potential for treating pseudoachondroplasia, a rare dwarfing condition, by relating the mechanisms of action of curcumin and resveratrol to molecular pathology. Specifically, we will examine the curcumin and resveratrol mechanisms of action related to endoplasmic reticulum stress, inflammation, oxidative stress, cartilage health, and pain. Additionally, the barriers to the effective use of nutraceuticals will be discussed. These challenges include poor bioavailability, variations in content and purity that lead to inconsistent results in clinical trials, as well as prevailing perceptions among both the public and medical professionals. Addressing these hurdles is crucial to realizing the full therapeutic potential of nutraceuticals in the context of pseudoachondroplasia and other health conditions that might benefit.
2023-10-20 | Early Resveratrol Treatment Mitigates Joint Degeneration and Dampens Pain in a Mouse Model of Pseudoachondroplasia (PSACH)
Pseudoachondroplasia (PSACH), a severe dwarfing condition associated with early-onset joint degeneration and lifelong joint pain, is caused by mutations in cartilage oligomeric matrix protein (COMP). The mechanisms underlying the mutant-COMP pathology have been defined using the MT-COMP mouse model of PSACH that has the common D469del mutation. Mutant-COMP protein does not fold properly, and it is retained in the rough endoplasmic reticulum (rER) of chondrocytes rather than being exported to the extracellular matrix (ECM), driving ER stress that stimulates oxidative stress and inflammation, driving a self-perpetuating cycle. CHOP (ER stress signaling protein) and TNFα inflammation drive high levels of mTORC1 signaling, shutting down autophagy and blocking ER clearance, resulting in premature loss of chondrocytes that negatively impacts linear growth and causes early joint degeneration in MT-COMP mice and PSACH. Previously, we have shown that resveratrol treatment from birth to 20 weeks prevents joint degeneration and decreases the pathological processes in articular chondrocytes. Resveratrol’s therapeutic mechanism of action in the mutant-COMP pathology was shown to act by primarily stimulating autophagy and reducing inflammation. Importantly, we demonstrated that MT-COMP mice experience pain consistent with PSACH joint pain. Here, we show, in the MT-COMP mouse, that resveratrol treatment must begin within 4 weeks to preserve joint health and reduce pain. Resveratrol treatment started at 6 or 8 weeks (to 20 weeks) was not effective in preventing joint degeneration. Collectively, our findings in MT-COMP mice show that there is a postnatal resveratrol treatment window wherein the inevitable mutant-COMP joint degeneration and pain can be prevented.
2023-03-24 | CurQ+, a Next-Generation Formulation of Curcumin, Ameliorates Growth Plate Chondrocyte Stress and Increases Limb Growth in a Mouse Model of Pseudoachondroplasia.
Mutations in cartilage oligomeric matrix protein (COMP) causes protein misfolding and accumulation in chondrocytes that compromises skeletal growth and joint health in pseudoachondroplasia (PSACH), a severe dwarfing condition. Using the MT-COMP mice, a murine model of PSACH, we showed that pathological autophagy blockage was key to the intracellular accumulation of mutant-COMP. Autophagy is blocked by elevated mTORC1 signaling, preventing ER clearance and ensuring chondrocyte death. We demonstrated that resveratrol reduces the growth plate pathology by relieving the autophagy blockage allowing the ER clearance of mutant-COMP, which partially rescues limb length. To expand potential PSACH treatment options, CurQ+, a uniquely absorbable formulation of curcumin, was tested in MT-COMP mice at doses of 82.3 (1X) and 164.6 mg/kg (2X). CurQ+ treatment of MT-COMP mice from 1 to 4 weeks postnatally decreased mutant COMP intracellular retention, inflammation, restoring both autophagy and chondrocyte proliferation. CurQ+ reduction of cellular stress in growth plate chondrocytes dramatically reduced chondrocyte death, normalized femur length at 2X 164.6 mg/kg and recovered 60% of lost limb growth at 1X 82.3 mg/kg. These results indicate that CurQ+ is a potential therapy for COMPopathy-associated lost limb growth, joint degeneration, and other conditions involving persistent inflammation, oxidative stress, and a block of autophagy.
2022-11-14 | Structure, evolution and expression of zebrafish cartilage oligomeric matrix protein (COMP, TSP5). CRISPR-Cas mutants show a dominant phenotype in myosepta
COMP (Cartilage Oligomeric Matrix Protein), also named thrombospondin-5, is a member of the thrombospondin family of extracellular matrix proteins. It is of clinical relevance, as in humans mutations in COMP lead to chondrodysplasias. The gene encoding zebrafish Comp is located on chromosome 11 in synteny with its mammalian orthologs. Zebrafish Comp has a domain structure identical to that of tetrapod COMP and shares 74% sequence similarity with murine COMP. Zebrafish comp is expressed from 5 hours post fertilization (hpf) on, while the protein is first detectable in somites of 11 hpf embryos. During development and in adults comp is strongly expressed in myosepta, craniofacial tendon and ligaments, around ribs and vertebra, but not in its name-giving tissue cartilage. As in mammals, zebrafish Comp forms pentamers. It is easily extracted from 5 days post fertilization (dpf) whole zebrafish. The lack of Comp expression in zebrafish cartilage implies that its cartilage function evolved recently in tetrapods. The expression in tendon and myosepta may indicate a more fundamental function, as in evolutionary distant Drosophila muscle-specific adhesion to tendon cells requires thrombospondin. A sequence encoding a calcium binding motif within the first TSP type-3 repeat of zebrafish Comp was targeted by CRISPR-Cas. The heterozygous and homozygous mutant Comp zebrafish displayed a patchy irregular Comp staining in 3 dpf myosepta, indicating a dominant phenotype. Electron microscopy revealed that the endoplasmic reticulum of myosepta fibroblasts is not affected in homozygous fish. The disorganized extracellular matrix may indicate that this mutation rather interferes with extracellular matrix assembly, similar to what is seen in a subgroup of chondrodysplasia patients. The early expression and easy detection of mutant Comp in zebrafish points to the potential of using the zebrafish model for large scale screening of small molecules that can improve secretion or function of disease-associated COMP mutants.
gene therapies
2026-03-09 | Genotype-phenotype correlations in PSACH/EDM1 patients with COMP gene variants: a comprehensive review of 830 cases.
Pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia-1 (EDM1) are two rare skeletal diseases that represent distinct endpoints of a continuous phenotypic spectrum with substantial clinical overlap, caused by variants in the gene coding cartilage oligomeric matrix protein (COMP). To summarize the clinical characteristics of PSACH/EDM1 and variants of COMP gene, as well as to explore the correlations between them. PubMed, China National Knowledge Infrastructure, and Wanfang were searched for case reports and case series of patients with genetic diagnosis of PSACH/EDM1 from the inception to 24 March 2025. The clinical characteristics and gene variants of enrolled patients were analyzed and compared to explore genotype-phenotype correlation. A total of 830 PSACH/EDM1 patients (471probands) harboring 224 different variants of COMP gene were enrolled from 106 articles, with missense variants accounting for the majority (80.8%). Exon 13 (183 probands, 38.9%) and type III (T3) repeat domain (413 probands, 87.7%) were the most commonly affected regions, with c.1417_1419del (p.Asp473del) being the most common hotspot variant. Compared with EDM1, PSACH manifested earlier age of onset (p < 0.001), shorter stature (p < 0.001), higher rates of lower limb deformity (p < 0.001), joint laxity (p = 0.041), anterior beaking of the vertebra and irregular/flared metaphysis (p < 0.001), while lower rate of joint pain/osteoarthritis (p < 0.001) and abnormal femoral head (p = 0.008). Missense variants in T3-4 and T3-5 were more likely to cause EDM1 (all p < 0.001), while those in T3-1 and T3-6 to T3-8 were associated with a greater frequency of PSACH (p = 0.002 to 0.023). Majority of in-frame variants were found in PSACH, as c.1417_1419del (p.Asp473del) being PSACH specific. PSACH exhibits more severe phenotypes than EDM1, even with phenotypic overlap. In-frame variants are more strongly associated with PSACH, as the hotspot variant p.Asp473del exclusively identified in PSACH. In contrast, missense variants in T3-4 and T3-5 show a stronger association with EDM1.
2026-02-23 | Micromelic Pseudoachondroplasia Simulating Rickets in a 9-Year-Old Boy
Pseudoachondroplastic dysplasia is a rare inherited disorder characterized by skeletal malformations resulting to short stature. These individuals are usually normal at birth but due to the abnormal skeletal growth or dysplasia, the skeleton becomes weakened and malformed. The skeletal deformities increase as the individual grows and gains weight. Affected individuals may have radiographic features simulating vitamin D deficiency. In addition, affected individuals may have spinal abnormalities including abnormally increased lumbar lordosis and kyphosis. This case is being presented because of its rarity and simulation of rickets in the growing young child.
2025-05-21 | [Clinical analysis in 15 pediatric patients with osteochondrodysplasias related to COMP gene variants].
Objective: To summarize the clinical and genetic characteristics of pseudoachondroplasia and multiple epiphyseal dysplasia caused by COMP gene variants in pediatric patients. Methods: This retrospective study concluded 15 pediatric patients with COMP-related pseudoachondroplasia and multiple epiphyseal dysplasia at Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine from July 2013 to August 2024. This paper analyzed clinical manifestations, laboratory findings and genetic testing. Results: This cohort comprised 15 pediatric patients (8 males and 7 females) with a diagnostic age of 5.3 (1.8,9.3) years. The major clinical presentations included abnormal gait (15/15), brachydactyly (11/15), genu varum (12/15), irregular metaphyseal changes (14/14) and epiphyseal dysplasia (14/14). Genetic analysis revealed 13 cases of pseudoachondroplasia and 2 multiple epiphyseal dysplasias cases associated with COMP gene variants. Fifteen variants were identified (8 pathogenic and 7 likely pathogenic), including 2 novel variants (c.1223A>G, c.1378G>C). Thirteen of these patients had variations clustered in exons 8-14 encoding the calmodulin-like domains, with c.1414_1419dupGACGAC emerging as a hotspot variant. Conclusions: COMP-related pseudoachondroplasia and multiple epiphyseal dysplasia predominantly manifest with gait abnormalities and skeletal deformities. COMP gene pathogenic variations were mainly located in calmodulin-like domains.
2023-05-05 | Health consequences of mutant cartilage oligomeric matrix protein and its relationship to abnormal growth and joint degeneration.
Cartilage oligomeric matrix protein (COMP), an extracellular matrix protein, has been shown to enhance proliferation and mechanical integrity in the matrix, supporting functions of the growth plate and articular cartilage. Mutations in COMP cause pseudoachondroplasia (PSACH), a severe dwarfing condition associated with premature joint degeneration and significant lifelong joint pain. The MT (mutant)-COMP mouse mimics PSACH with decreased limb growth, early joint degeneration and pain. Ablation of endoplasmic reticulum stress CHOP signaling eliminated pain and prevented joint degeneration. The health effects of mutant COMP are discussed in relation to cellular/chondrocyte stress in the growth plate, articular cartilage and nearby tissues, and the implications for therapeutic approaches. There are many similarities between osteoarthritis and mutant-COMP protein-induced joint degeneration, suggesting that the relevance of findings in the joints may extend beyond PSACH to idiopathic primary OA.
2014-02-18 | Abnormal Chondrocyte Apoptosis in the Cartilage Growth Plate is Influenced by Genetic Background and Deletion of CHOP in a Targeted Mouse Model of Pseudoachondroplasia
Pseudoachondroplasia (PSACH) is an autosomal dominant skeletal dysplasia caused by mutations in cartilage oligomeric matrix protein (COMP) and characterised by short limbed dwarfism and early onset osteoarthritis. Mouse models of PSACH show variable retention of mutant COMP in the ER of chondrocytes, however, in each case a different stress pathway is activated and the underlying disease mechanisms remain largely unknown. T585M COMP mutant mice are a model of moderate PSACH and demonstrate a mild ER stress response. Although mutant COMP is not retained in significant quantities within the ER of chondrocytes, both BiP and the pro-apoptotic ER stress-related transcription factor CHOP are mildly elevated, whilst bcl-2 levels are decreased, resulting in increased and spatially dysregulated chondrocyte apoptosis. To determine whether the abnormal chondrocyte apoptosis observed in the growth plate of mutant mice is CHOP-mediated, we bred T585M COMP mutant mice with CHOP-null mice to homozygosity, and analysed the resulting phenotype. Although abnormal apoptosis was alleviated in the resting zone following CHOP deletion, the mutant growth plates were generally more disorganised. Furthermore, the bone lengths of COMP mutant CHOP null mice were significantly shorter at 9 weeks of age when compared to the COMP mutant mice, including a significant difference in the skull length. Overall, these data demonstrate that CHOP-mediated apoptosis is an early event in the pathobiology of PSACH and suggest that the lack of CHOP, in conjunction with a COMP mutation, may lead to aggravation of the skeletal phenotype via a potentially synergistic effect on endochondral ossification.
oligonucleotides
2025-01-11 | Loss of CHOP Prevents Joint Degeneration and Pain in a Mouse Model of Pseudoachondroplasia.
Pseudoachondroplasia (PSACH), a severe dwarfing condition characterized by impaired skeletal growth and early joint degeneration, results from mutations in cartilage oligomeric matrix protein (COMP). These mutations disrupt normal protein folding, leading to the accumulation of misfolded COMP in chondrocytes. The MT-COMP mouse is a murine model of PSACH that expresses D469del human COMP in response to doxycycline and replicates the PSACH chondrocyte and clinical pathology. The basis for the mutant-COMP pathology involves endoplasmic reticulum (ER) stress signaling through the PERK/eIF2α/CHOP pathway. C/EBP homologous protein (CHOP), in conjunction with a TNFα inflammatory process, upregulates mTORC1, hindering autophagy clearance of mutant COMP protein. Life-long joint pain/degeneration diminishes quality of life, and treatments other than joint replacements are urgently needed. To assess whether molecules that reduce CHOP activity should be considered as a potential treatment for PSACH, we evaluated MT-COMP mice with 50% CHOP (MT-COMP/CHOP+/-), antisense oligonucleotide (ASO)-mediated CHOP knockdown, and complete CHOP ablation (MT-COMP/CHOP-/-). While earlier studies demonstrated that loss of CHOP in MT-COMP mice reduced intracellular retention, inflammation, and growth plate chondrocyte death, we now show that it did not normalize limb growth. ASO treatment reduced CHOP mRNA by approximately 60%, as measured by RT-qPCR, but did not improve limb length similar to MT-COMP/CHOP+/-. Interestingly, both 50% genetic reduction and complete loss of CHOP alleviated pain, while total ablation of CHOP in MT-COMP mice was necessary to preserve joint health. These results indicate that (1) CHOP reduction therapy is not an effective strategy for improving limb length and (2) pain and chondrocyte pathology are more responsive to intervention than the prevention of joint damage.
2019-02-13 | Mutant cartilage oligomeric matrix protein (COMP) compromises bone integrity, joint function and the balance between adipogenesis and osteogenesis.
Mutations in COMP (cartilage oligomeric matrix protein) cause severe long bone shortening in mice and humans. Previously, we showed that massive accumulation of misfolded COMP in the ER of growth plate chondrocytes in our MT-COMP mouse model of pseudoachondroplasia (PSACH) causes premature chondrocyte death and loss of linear growth. Premature chondrocyte death results from activation of oxidative stress and inflammation through the CHOP-ER pathway and is reduced by removing CHOP or by anti-inflammatory or antioxidant therapies. Although the mutant COMP chondrocyte pathologic mechanism is now recognized, the effect of mutant COMP on bone quality and joint health (laxity) is largely unknown. Applying multiple analytic approaches, we describe a novel mechanism by which the deleterious consequences of mutant COMP retention results in upregulation of miR-223 disturbing the adipogenesis - osteogenesis balance. This results in reduction in bone mineral density, bone quality, mechanical strength and subchondral bone thickness. These, in addition to abnormal patterns of ossification at the ends of the femoral bones likely contribute to precocious osteoarthritis (OA) of the hips and knees in the MT-COMP mouse and PSACH. Moreover, joint laxity is compromised by abnormally thin ligaments. Altogether, these novel findings align with the PSACH phenotype of delayed ossification and bone age, extreme joint laxity and joint erosion, and extend our understanding of the underlying processes that affect bone in PSACH. These results introduce a novel finding that miR-223 is involved in the ossification defect in MT-COMP mice making it a therapeutic target.
2017-02-03 | Antisense Reduction of Mutant COMP Reduces Growth Plate Chondrocyte Pathology
Mutations in cartilage oligomeric matrix protein cause pseudoachondroplasia, a severe disproportionate short stature disorder. Mutant cartilage oligomeric matrix protein produces massive intracellular retention of cartilage oligomeric matrix protein, stimulating ER and oxidative stresses and inflammation, culminating in post-natal loss of growth plate chondrocytes, which compromises linear bone growth. Treatments for pseudoachondroplasia are limited because cartilage is relatively avascular and considered inaccessible. Here we report successful delivery and treatment using antisense oligonucleotide technology in our transgenic pseudoachondroplasia mouse model. We demonstrate delivery of human cartilage oligomeric matrix protein-specific antisense oligonucleotides to cartilage and reduction of cartilage oligomeric matrix protein expression, which largely alleviates pseudoachondroplasia growth plate chondrocyte pathology. One antisense oligonucleotide reduced steady-state levels of cartilage oligomeric matrix protein mRNA and dampened intracellular retention of mutant cartilage oligomeric matrix protein, leading to a reduction of inflammatory markers and cell death and partial restoration of proliferation. This novel and exciting work demonstrates that antisense-based therapy is a viable approach for treating pseudoachondroplasia and other human cartilage disorders. Mutations in cartilage oligomeric matrix protein cause pseudoachondroplasia, a severe disproportionate short stature disorder. Mutant cartilage oligomeric matrix protein produces massive intracellular retention of cartilage oligomeric matrix protein, stimulating ER and oxidative stresses and inflammation, culminating in post-natal loss of growth plate chondrocytes, which compromises linear bone growth. Treatments for pseudoachondroplasia are limited because cartilage is relatively avascular and considered inaccessible. Here we report successful delivery and treatment using antisense oligonucleotide technology in our transgenic pseudoachondroplasia mouse model. We demonstrate delivery of human cartilage oligomeric matrix protein-specific antisense oligonucleotides to cartilage and reduction of cartilage oligomeric matrix protein expression, which largely alleviates pseudoachondroplasia growth plate chondrocyte pathology. One antisense oligonucleotide reduced steady-state levels of cartilage oligomeric matrix protein mRNA and dampened intracellular retention of mutant cartilage oligomeric matrix protein, leading to a reduction of inflammatory markers and cell death and partial restoration of proliferation. This novel and exciting work demonstrates that antisense-based therapy is a viable approach for treating pseudoachondroplasia and other human cartilage disorders.
small molecules
2025-04-28 | CurQ+ With Resveratrol Diminish Joint Pain in a Child With Pseudoachondroplasia: A Case Report.
This case report details the successful use of over-the-counter resveratrol and CurQ+ in a five-year-old with pseudoachondroplasia (PSACH), a severe dwarfing condition caused by mutations in cartilage oligomeric matrix protein (COMP). Disproportionate short stature, abnormal joints, joint deformities, and pain starting in early childhood are characteristic findings. Adult treatments include non-steroidal anti-inflammatory drugs (NSAIDs) and joint replacement to manage joint pain. Childhood pain goes largely untreated given the concern of daily use of NSAIDs in the very young. Recently, resveratrol has been shown to reduce pain and CurQ+ improves growth in a mouse model of PSACH. The use of these over-the-counter supplements has been adopted by some families with PSACH children. One such case in this report has a daily intake of resveratrol and CurQ+ at 125 mg of trans-resveratrol and 0.66 g, respectively, in the 16.6 kg child. This resulted in a dosage of 7.6 mg/kg of resveratrol and 40 mg/kg of CurQ+ daily. To date, no side effects from CurQ+ and resveratrol were reported in the child. Pain made walking to school very difficult (600 m) prior to the use of supplements and now the child walks to school without assistance or complaint.
2024-01-27 | Curcumin and Resveratrol: Nutraceuticals with so Much Potential for Pseudoachondroplasia and Other ER-Stress Conditions
Natural products with health benefits, nutraceuticals, have shown considerable promise in many studies; however, this potential has yet to translate into widespread clinical use for any condition. Notably, many drugs currently on the market, including the first analgesic aspirin, are derived from plant extracts, emphasizing the historical significance of natural products in drug development. Curcumin and resveratrol, well-studied nutraceuticals, have excellent safety profiles with relatively mild side effects. Their long history of safe use and the natural origins of numerous drugs contrast with the unfavorable reputation associated with nutraceuticals. This review aims to explore the nutraceutical potential for treating pseudoachondroplasia, a rare dwarfing condition, by relating the mechanisms of action of curcumin and resveratrol to molecular pathology. Specifically, we will examine the curcumin and resveratrol mechanisms of action related to endoplasmic reticulum stress, inflammation, oxidative stress, cartilage health, and pain. Additionally, the barriers to the effective use of nutraceuticals will be discussed. These challenges include poor bioavailability, variations in content and purity that lead to inconsistent results in clinical trials, as well as prevailing perceptions among both the public and medical professionals. Addressing these hurdles is crucial to realizing the full therapeutic potential of nutraceuticals in the context of pseudoachondroplasia and other health conditions that might benefit.
2023-10-20 | Early Resveratrol Treatment Mitigates Joint Degeneration and Dampens Pain in a Mouse Model of Pseudoachondroplasia (PSACH)
Pseudoachondroplasia (PSACH), a severe dwarfing condition associated with early-onset joint degeneration and lifelong joint pain, is caused by mutations in cartilage oligomeric matrix protein (COMP). The mechanisms underlying the mutant-COMP pathology have been defined using the MT-COMP mouse model of PSACH that has the common D469del mutation. Mutant-COMP protein does not fold properly, and it is retained in the rough endoplasmic reticulum (rER) of chondrocytes rather than being exported to the extracellular matrix (ECM), driving ER stress that stimulates oxidative stress and inflammation, driving a self-perpetuating cycle. CHOP (ER stress signaling protein) and TNFα inflammation drive high levels of mTORC1 signaling, shutting down autophagy and blocking ER clearance, resulting in premature loss of chondrocytes that negatively impacts linear growth and causes early joint degeneration in MT-COMP mice and PSACH. Previously, we have shown that resveratrol treatment from birth to 20 weeks prevents joint degeneration and decreases the pathological processes in articular chondrocytes. Resveratrol’s therapeutic mechanism of action in the mutant-COMP pathology was shown to act by primarily stimulating autophagy and reducing inflammation. Importantly, we demonstrated that MT-COMP mice experience pain consistent with PSACH joint pain. Here, we show, in the MT-COMP mouse, that resveratrol treatment must begin within 4 weeks to preserve joint health and reduce pain. Resveratrol treatment started at 6 or 8 weeks (to 20 weeks) was not effective in preventing joint degeneration. Collectively, our findings in MT-COMP mice show that there is a postnatal resveratrol treatment window wherein the inevitable mutant-COMP joint degeneration and pain can be prevented.
2023-03-24 | CurQ+, a Next-Generation Formulation of Curcumin, Ameliorates Growth Plate Chondrocyte Stress and Increases Limb Growth in a Mouse Model of Pseudoachondroplasia.
Mutations in cartilage oligomeric matrix protein (COMP) causes protein misfolding and accumulation in chondrocytes that compromises skeletal growth and joint health in pseudoachondroplasia (PSACH), a severe dwarfing condition. Using the MT-COMP mice, a murine model of PSACH, we showed that pathological autophagy blockage was key to the intracellular accumulation of mutant-COMP. Autophagy is blocked by elevated mTORC1 signaling, preventing ER clearance and ensuring chondrocyte death. We demonstrated that resveratrol reduces the growth plate pathology by relieving the autophagy blockage allowing the ER clearance of mutant-COMP, which partially rescues limb length. To expand potential PSACH treatment options, CurQ+, a uniquely absorbable formulation of curcumin, was tested in MT-COMP mice at doses of 82.3 (1X) and 164.6 mg/kg (2X). CurQ+ treatment of MT-COMP mice from 1 to 4 weeks postnatally decreased mutant COMP intracellular retention, inflammation, restoring both autophagy and chondrocyte proliferation. CurQ+ reduction of cellular stress in growth plate chondrocytes dramatically reduced chondrocyte death, normalized femur length at 2X 164.6 mg/kg and recovered 60% of lost limb growth at 1X 82.3 mg/kg. These results indicate that CurQ+ is a potential therapy for COMPopathy-associated lost limb growth, joint degeneration, and other conditions involving persistent inflammation, oxidative stress, and a block of autophagy.
2022-11-14 | Structure, evolution and expression of zebrafish cartilage oligomeric matrix protein (COMP, TSP5). CRISPR-Cas mutants show a dominant phenotype in myosepta
COMP (Cartilage Oligomeric Matrix Protein), also named thrombospondin-5, is a member of the thrombospondin family of extracellular matrix proteins. It is of clinical relevance, as in humans mutations in COMP lead to chondrodysplasias. The gene encoding zebrafish Comp is located on chromosome 11 in synteny with its mammalian orthologs. Zebrafish Comp has a domain structure identical to that of tetrapod COMP and shares 74% sequence similarity with murine COMP. Zebrafish comp is expressed from 5 hours post fertilization (hpf) on, while the protein is first detectable in somites of 11 hpf embryos. During development and in adults comp is strongly expressed in myosepta, craniofacial tendon and ligaments, around ribs and vertebra, but not in its name-giving tissue cartilage. As in mammals, zebrafish Comp forms pentamers. It is easily extracted from 5 days post fertilization (dpf) whole zebrafish. The lack of Comp expression in zebrafish cartilage implies that its cartilage function evolved recently in tetrapods. The expression in tendon and myosepta may indicate a more fundamental function, as in evolutionary distant Drosophila muscle-specific adhesion to tendon cells requires thrombospondin. A sequence encoding a calcium binding motif within the first TSP type-3 repeat of zebrafish Comp was targeted by CRISPR-Cas. The heterozygous and homozygous mutant Comp zebrafish displayed a patchy irregular Comp staining in 3 dpf myosepta, indicating a dominant phenotype. Electron microscopy revealed that the endoplasmic reticulum of myosepta fibroblasts is not affected in homozygous fish. The disorganized extracellular matrix may indicate that this mutation rather interferes with extracellular matrix assembly, similar to what is seen in a subgroup of chondrodysplasia patients. The early expression and easy detection of mutant Comp in zebrafish points to the potential of using the zebrafish model for large scale screening of small molecules that can improve secretion or function of disease-associated COMP mutants.
gene therapies
2026-03-09 | Genotype-phenotype correlations in PSACH/EDM1 patients with COMP gene variants: a comprehensive review of 830 cases.
Pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia-1 (EDM1) are two rare skeletal diseases that represent distinct endpoints of a continuous phenotypic spectrum with substantial clinical overlap, caused by variants in the gene coding cartilage oligomeric matrix protein (COMP). To summarize the clinical characteristics of PSACH/EDM1 and variants of COMP gene, as well as to explore the correlations between them. PubMed, China National Knowledge Infrastructure, and Wanfang were searched for case reports and case series of patients with genetic diagnosis of PSACH/EDM1 from the inception to 24 March 2025. The clinical characteristics and gene variants of enrolled patients were analyzed and compared to explore genotype-phenotype correlation. A total of 830 PSACH/EDM1 patients (471probands) harboring 224 different variants of COMP gene were enrolled from 106 articles, with missense variants accounting for the majority (80.8%). Exon 13 (183 probands, 38.9%) and type III (T3) repeat domain (413 probands, 87.7%) were the most commonly affected regions, with c.1417_1419del (p.Asp473del) being the most common hotspot variant. Compared with EDM1, PSACH manifested earlier age of onset (p < 0.001), shorter stature (p < 0.001), higher rates of lower limb deformity (p < 0.001), joint laxity (p = 0.041), anterior beaking of the vertebra and irregular/flared metaphysis (p < 0.001), while lower rate of joint pain/osteoarthritis (p < 0.001) and abnormal femoral head (p = 0.008). Missense variants in T3-4 and T3-5 were more likely to cause EDM1 (all p < 0.001), while those in T3-1 and T3-6 to T3-8 were associated with a greater frequency of PSACH (p = 0.002 to 0.023). Majority of in-frame variants were found in PSACH, as c.1417_1419del (p.Asp473del) being PSACH specific. PSACH exhibits more severe phenotypes than EDM1, even with phenotypic overlap. In-frame variants are more strongly associated with PSACH, as the hotspot variant p.Asp473del exclusively identified in PSACH. In contrast, missense variants in T3-4 and T3-5 show a stronger association with EDM1.
2026-02-23 | Micromelic Pseudoachondroplasia Simulating Rickets in a 9-Year-Old Boy
Pseudoachondroplastic dysplasia is a rare inherited disorder characterized by skeletal malformations resulting to short stature. These individuals are usually normal at birth but due to the abnormal skeletal growth or dysplasia, the skeleton becomes weakened and malformed. The skeletal deformities increase as the individual grows and gains weight. Affected individuals may have radiographic features simulating vitamin D deficiency. In addition, affected individuals may have spinal abnormalities including abnormally increased lumbar lordosis and kyphosis. This case is being presented because of its rarity and simulation of rickets in the growing young child.
2025-05-21 | [Clinical analysis in 15 pediatric patients with osteochondrodysplasias related to COMP gene variants].
Objective: To summarize the clinical and genetic characteristics of pseudoachondroplasia and multiple epiphyseal dysplasia caused by COMP gene variants in pediatric patients. Methods: This retrospective study concluded 15 pediatric patients with COMP-related pseudoachondroplasia and multiple epiphyseal dysplasia at Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine from July 2013 to August 2024. This paper analyzed clinical manifestations, laboratory findings and genetic testing. Results: This cohort comprised 15 pediatric patients (8 males and 7 females) with a diagnostic age of 5.3 (1.8,9.3) years. The major clinical presentations included abnormal gait (15/15), brachydactyly (11/15), genu varum (12/15), irregular metaphyseal changes (14/14) and epiphyseal dysplasia (14/14). Genetic analysis revealed 13 cases of pseudoachondroplasia and 2 multiple epiphyseal dysplasias cases associated with COMP gene variants. Fifteen variants were identified (8 pathogenic and 7 likely pathogenic), including 2 novel variants (c.1223A>G, c.1378G>C). Thirteen of these patients had variations clustered in exons 8-14 encoding the calmodulin-like domains, with c.1414_1419dupGACGAC emerging as a hotspot variant. Conclusions: COMP-related pseudoachondroplasia and multiple epiphyseal dysplasia predominantly manifest with gait abnormalities and skeletal deformities. COMP gene pathogenic variations were mainly located in calmodulin-like domains.
2023-05-05 | Health consequences of mutant cartilage oligomeric matrix protein and its relationship to abnormal growth and joint degeneration.
Cartilage oligomeric matrix protein (COMP), an extracellular matrix protein, has been shown to enhance proliferation and mechanical integrity in the matrix, supporting functions of the growth plate and articular cartilage. Mutations in COMP cause pseudoachondroplasia (PSACH), a severe dwarfing condition associated with premature joint degeneration and significant lifelong joint pain. The MT (mutant)-COMP mouse mimics PSACH with decreased limb growth, early joint degeneration and pain. Ablation of endoplasmic reticulum stress CHOP signaling eliminated pain and prevented joint degeneration. The health effects of mutant COMP are discussed in relation to cellular/chondrocyte stress in the growth plate, articular cartilage and nearby tissues, and the implications for therapeutic approaches. There are many similarities between osteoarthritis and mutant-COMP protein-induced joint degeneration, suggesting that the relevance of findings in the joints may extend beyond PSACH to idiopathic primary OA.
2014-02-18 | Abnormal Chondrocyte Apoptosis in the Cartilage Growth Plate is Influenced by Genetic Background and Deletion of CHOP in a Targeted Mouse Model of Pseudoachondroplasia
Pseudoachondroplasia (PSACH) is an autosomal dominant skeletal dysplasia caused by mutations in cartilage oligomeric matrix protein (COMP) and characterised by short limbed dwarfism and early onset osteoarthritis. Mouse models of PSACH show variable retention of mutant COMP in the ER of chondrocytes, however, in each case a different stress pathway is activated and the underlying disease mechanisms remain largely unknown. T585M COMP mutant mice are a model of moderate PSACH and demonstrate a mild ER stress response. Although mutant COMP is not retained in significant quantities within the ER of chondrocytes, both BiP and the pro-apoptotic ER stress-related transcription factor CHOP are mildly elevated, whilst bcl-2 levels are decreased, resulting in increased and spatially dysregulated chondrocyte apoptosis. To determine whether the abnormal chondrocyte apoptosis observed in the growth plate of mutant mice is CHOP-mediated, we bred T585M COMP mutant mice with CHOP-null mice to homozygosity, and analysed the resulting phenotype. Although abnormal apoptosis was alleviated in the resting zone following CHOP deletion, the mutant growth plates were generally more disorganised. Furthermore, the bone lengths of COMP mutant CHOP null mice were significantly shorter at 9 weeks of age when compared to the COMP mutant mice, including a significant difference in the skull length. Overall, these data demonstrate that CHOP-mediated apoptosis is an early event in the pathobiology of PSACH and suggest that the lack of CHOP, in conjunction with a COMP mutation, may lead to aggravation of the skeletal phenotype via a potentially synergistic effect on endochondral ossification.
oligonucleotides
2025-01-11 | Loss of CHOP Prevents Joint Degeneration and Pain in a Mouse Model of Pseudoachondroplasia.
Pseudoachondroplasia (PSACH), a severe dwarfing condition characterized by impaired skeletal growth and early joint degeneration, results from mutations in cartilage oligomeric matrix protein (COMP). These mutations disrupt normal protein folding, leading to the accumulation of misfolded COMP in chondrocytes. The MT-COMP mouse is a murine model of PSACH that expresses D469del human COMP in response to doxycycline and replicates the PSACH chondrocyte and clinical pathology. The basis for the mutant-COMP pathology involves endoplasmic reticulum (ER) stress signaling through the PERK/eIF2α/CHOP pathway. C/EBP homologous protein (CHOP), in conjunction with a TNFα inflammatory process, upregulates mTORC1, hindering autophagy clearance of mutant COMP protein. Life-long joint pain/degeneration diminishes quality of life, and treatments other than joint replacements are urgently needed. To assess whether molecules that reduce CHOP activity should be considered as a potential treatment for PSACH, we evaluated MT-COMP mice with 50% CHOP (MT-COMP/CHOP+/-), antisense oligonucleotide (ASO)-mediated CHOP knockdown, and complete CHOP ablation (MT-COMP/CHOP-/-). While earlier studies demonstrated that loss of CHOP in MT-COMP mice reduced intracellular retention, inflammation, and growth plate chondrocyte death, we now show that it did not normalize limb growth. ASO treatment reduced CHOP mRNA by approximately 60%, as measured by RT-qPCR, but did not improve limb length similar to MT-COMP/CHOP+/-. Interestingly, both 50% genetic reduction and complete loss of CHOP alleviated pain, while total ablation of CHOP in MT-COMP mice was necessary to preserve joint health. These results indicate that (1) CHOP reduction therapy is not an effective strategy for improving limb length and (2) pain and chondrocyte pathology are more responsive to intervention than the prevention of joint damage.
2019-02-13 | Mutant cartilage oligomeric matrix protein (COMP) compromises bone integrity, joint function and the balance between adipogenesis and osteogenesis.
Mutations in COMP (cartilage oligomeric matrix protein) cause severe long bone shortening in mice and humans. Previously, we showed that massive accumulation of misfolded COMP in the ER of growth plate chondrocytes in our MT-COMP mouse model of pseudoachondroplasia (PSACH) causes premature chondrocyte death and loss of linear growth. Premature chondrocyte death results from activation of oxidative stress and inflammation through the CHOP-ER pathway and is reduced by removing CHOP or by anti-inflammatory or antioxidant therapies. Although the mutant COMP chondrocyte pathologic mechanism is now recognized, the effect of mutant COMP on bone quality and joint health (laxity) is largely unknown. Applying multiple analytic approaches, we describe a novel mechanism by which the deleterious consequences of mutant COMP retention results in upregulation of miR-223 disturbing the adipogenesis - osteogenesis balance. This results in reduction in bone mineral density, bone quality, mechanical strength and subchondral bone thickness. These, in addition to abnormal patterns of ossification at the ends of the femoral bones likely contribute to precocious osteoarthritis (OA) of the hips and knees in the MT-COMP mouse and PSACH. Moreover, joint laxity is compromised by abnormally thin ligaments. Altogether, these novel findings align with the PSACH phenotype of delayed ossification and bone age, extreme joint laxity and joint erosion, and extend our understanding of the underlying processes that affect bone in PSACH. These results introduce a novel finding that miR-223 is involved in the ossification defect in MT-COMP mice making it a therapeutic target.
2017-02-03 | Antisense Reduction of Mutant COMP Reduces Growth Plate Chondrocyte Pathology
Mutations in cartilage oligomeric matrix protein cause pseudoachondroplasia, a severe disproportionate short stature disorder. Mutant cartilage oligomeric matrix protein produces massive intracellular retention of cartilage oligomeric matrix protein, stimulating ER and oxidative stresses and inflammation, culminating in post-natal loss of growth plate chondrocytes, which compromises linear bone growth. Treatments for pseudoachondroplasia are limited because cartilage is relatively avascular and considered inaccessible. Here we report successful delivery and treatment using antisense oligonucleotide technology in our transgenic pseudoachondroplasia mouse model. We demonstrate delivery of human cartilage oligomeric matrix protein-specific antisense oligonucleotides to cartilage and reduction of cartilage oligomeric matrix protein expression, which largely alleviates pseudoachondroplasia growth plate chondrocyte pathology. One antisense oligonucleotide reduced steady-state levels of cartilage oligomeric matrix protein mRNA and dampened intracellular retention of mutant cartilage oligomeric matrix protein, leading to a reduction of inflammatory markers and cell death and partial restoration of proliferation. This novel and exciting work demonstrates that antisense-based therapy is a viable approach for treating pseudoachondroplasia and other human cartilage disorders. Mutations in cartilage oligomeric matrix protein cause pseudoachondroplasia, a severe disproportionate short stature disorder. Mutant cartilage oligomeric matrix protein produces massive intracellular retention of cartilage oligomeric matrix protein, stimulating ER and oxidative stresses and inflammation, culminating in post-natal loss of growth plate chondrocytes, which compromises linear bone growth. Treatments for pseudoachondroplasia are limited because cartilage is relatively avascular and considered inaccessible. Here we report successful delivery and treatment using antisense oligonucleotide technology in our transgenic pseudoachondroplasia mouse model. We demonstrate delivery of human cartilage oligomeric matrix protein-specific antisense oligonucleotides to cartilage and reduction of cartilage oligomeric matrix protein expression, which largely alleviates pseudoachondroplasia growth plate chondrocyte pathology. One antisense oligonucleotide reduced steady-state levels of cartilage oligomeric matrix protein mRNA and dampened intracellular retention of mutant cartilage oligomeric matrix protein, leading to a reduction of inflammatory markers and cell death and partial restoration of proliferation. This novel and exciting work demonstrates that antisense-based therapy is a viable approach for treating pseudoachondroplasia and other human cartilage disorders.
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