RARE DISEASE
Hypochondroplasia
Hypochondroplasia
Hypochondroplasia
Drug discovery
4
drugs
With orphan designations
Overview
Hypochondroplasia is a mild skeletal dysplasia caused by FGFR3 mutations, leading to disproportionate short stature, limb shortening, and subtle dysmorphic features. Diagnosis combines clinical assessment, radiography (narrowed lumbar spine, short femoral necks), and genetic testing. Complications include spinal stenosis, leg bowing, and mild neurocognitive issues in ~10% [1][6][14]. Management focuses on monitoring growth, orthopedic interventions, and emerging therapies like vosoritide [3][8][12]. Life expectancy is normal.
Categories: rare bone diseases, rare developmental anomalies during embryogenesis, rare genetic diseases
Research Papers
109 drug discovery papers about Hypochondroplasia, with 3 first-in-class and 1 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
109 drug discovery papers about Hypochondroplasia, with 3 first-in-class and 1 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
categories:
Small molecules
cell therapies
2024-02-08 | Prophylactic Intramedullary Rodding After Femoral Lengthening in Patients With Achondroplasia and Hypochondroplasia.
Femoral fracture after femoral lengthening in patients with achondroplasia and hypochondroplasia is a frequent complication, occurring in up to 30%. The purpose of this study is to demonstrate the effectiveness of prophylactic intramedullary rodding in preventing this complication. Multicenter retrospective study involving 86 femoral lengthening procedures in 43 patients with achondroplasia or hypochondroplasia. Forty-two femora (21 patients) were prophylactically managed with intramedullary Rush rodding after external fixation removal (11 females and 10 males, mean age 14.6 years) compared with 44 femora (22 patients) without prophylactic intramedullary rodding (13 females and 9 males, mean age 15.2 years). The mean amount of lengthening in the rodding group was 13.3 cm (52.6%) with an External Fixation Index of 25.8 days/cm; in patients without rodding was 14.3 cm (61.5%) and 24.5 days/cm, respectively. Seven cases (15.9%) without rodding developed fractures. Four of them required surgical correction due to displacement or shortening. Only 1 patient (2.4%) had fracture of the femur after prophylactic rodding, and surgery was not required. The incidence of femur fracture was significantly lower in the prophylactic rodding group compared with the nonrodding group (2.4% vs. 15.9%, respectively; P =0.034). There were no cases of infection or avascular necrosis. Prophylactic intramedullary rodding is a safe and effective method for preventing femoral fractures after femoral lengthening in patients with achondroplasia or hypochondroplasia. Level III-a retrospective comparative study.
2007-09-01 | Distraction Osteogenesis of the Lower Extremity in Patients With Achondroplasia/Hypochondroplasia Treated With Transplantation of Culture-Expanded Bone Marrow Cells and Platelet-Rich Plasma
Background: Longer treatment period in distraction osteogenesis (DO) of the lower extremity leads to more frequent complications. We have developed a new technique of transplantation of culture-expanded bone marrow cells (BMCs) and platelet-rich plasma (PRP) during DO to accelerate new bone formation. To assess the efficacy of this cell therapy, retrospective comparative study was conducted between the bones treated with BMC and PRP and the bones treated without BMC and PRP during DO in patients with achondroplasia (ACH) and hypochondroplasia (HCH). Methods: Fifty-six bones in 20 patients (ACH, 16; HCH, 4) that were lengthened in our hospital were divided into 2 groups. Twenty-four bones (femora, 12; tibiae, 12) in 11 patients (boys, 7; girls, 4) were treated with BMC and PRP transplantation (BMC-PRP group), whereas 32 bones (femora, 14; tibiae, 18) in 9 patients (boys, 3; girls, 6) did not undergo additional cell therapy (control group). The parameters, including the age at operation, the increase in length, and the healing index, were compared between the 2 groups. The clinical outcome was also compared between the femoral and tibial lengthenings. Results: Bone marrow cells (average number, ± SD, 3.2 ± 1.37 × 107 cells) and PRP (average platelet concentration ± SD, 2.36 ± 0.57 × 106 cells/μL) were transplanted. Although there were no significant differences in the age at operation and the length gained between the 2 groups, the average healing index of the BMC-PRP group (27.1 ± 6.89 d/cm) was significantly lower than that of the control group (36.2 ± 10.4 d/cm) (P = 0.0005). The femoral lengthening showed significantly faster healing than did the tibial lengthening in the BMC-PRP group (P = 0.0092). Conclusions: Transplantation of BMC and PRP shortened the treatment period by accelerating new bone regeneration during DO of the lower extremity in patients with ACH and HCH, especially in the femoral lengthening. Level of Evidence: Therapeutic studies, level III (retrospective comparative study).
1974-01-01 | Reconstitution of Cellular Immune Function in a Child with Thymic Aplasia by Foetal Thymus Grafting
Summary: A two-year-old, male non-identical twin with megacolon, hypochondroplasia of bone and absence of a thymus-dependent lymphoid population is described. No parathyroid dysfunction was detected and humoral immune function was intact, although only an IgM response was elicited by a thymus dependent antigen. Repeated grafting of unmatched thymus tissue from a human foetus of 12–16 weeks gestation has resulted in significant immunological re-constitution and clinical improvement.
proteins
2026-06-03 | Navepegritide: First Approval.
Navepegritide (YUVIWEL®) is a prodrug of C-type natriuretic peptide (CNP) developed by Ascendis Pharma for the treatment of achondroplasia and is being investigated for hypochondroplasia. Navepegritide is administered once weekly and designed to provide sustained release and continuous exposure of active CNP, which is needed to counteract the overactive fibroblast growth factor receptor 3 signaling in achondroplasia, resulting in improved growth velocity. Navepegritide recently received accelerated approval in the USA for increasing linear growth in paediatric patients aged ≥ 2 years with achondroplasia with open epiphyses. This article summarizes the milestones in the development of navepegritide leading to this first approval for achondroplasia.
2026-05-25 | Navepegritide: First Approval
DeclarationsAuthorship and Conflict of interest During the peer review process the manufacturer of the agent under review was offered an opportunity to comment on the article. Changes resulting from any comments received were made by the authors on the basis of scientific completeness and accuracy. Connie Kang is a salaried employee of Adis International Ltd/Springer Nature, and declares no relevant conflicts of interest. All authors contributed to this article and are responsible for its content.Ethics approval, Consent to participate, Consent to publish, Availability of data and material, Code availability Not applicable.
Additional information about this Adis Drug Review can be found here.
Abstract
Navepegritide (YUVIWEL®) is a prodrug of C-type natriuretic peptide (CNP) developed by Ascendis Pharma for the treatment of achondroplasia and is being investigated for hypochondroplasia. Navepegritide is administered once weekly and designed to provide sustained release and continuous exposure of active CNP, which is needed to counteract the overactive fibroblast growth factor receptor 3 signaling in achondroplasia, resulting in improved growth velocity. Navepegritide recently received accelerated approval in the USA for increasing linear growth in paediatric patients aged ≥ 2 years with achondroplasia with open epiphyses. This article summarizes the milestones in the development of navepegritide leading to this first approval for achondroplasia.
© Springer Nature Switzerland AG 2026
2026-01-01 | P237: Incidence of neurocognitive conditions in hypochondroplasia
Hypochondroplasia is one of several well-described skeletal dysplasias that occur along the FGFR3-spectrum. While individuals with hypochondroplasia generally present more mildly from a skeletal perspective than achondroplasia, an increased incidence of attention/hyperactivity concerns, learning, and intellectual disability as well as seizures, has been reported in this population. For counseling and screening purposes there is limited information on both risk of neurocognitive diagnoses and role of MRI as a predictor of neurocognitive outcomes.
2026-01-01 | P107: Experimental FGFR3 saturation mutagenesis and big-data integration identify 20 novel pathogenic variants in hypochondroplasia*
Hypochondroplasia is part of a spectrum of skeletal dysplasias caused by activating variants in FGFR3. Due to its clinical heterogeneity, diagnosis of hypochondroplasia, one of the most common FGFR3 disorders, is challenging without genetic confirmation.
2024-04-11 | Vosoritide treatment for children with hypochondroplasia: a phase 2 trial
Hypochondroplasia is a rare autosomal dominant skeletal dysplasia due to activating variants in FGFR3. It presents with disproportionate short stature with a wide range of clinical severity. There are currently no approved medications to treat short stature in children with hypochondroplasia. Vosoritide is a C-type natriuretic peptide analog that was recently approved for improving growth in children with achondroplasia. We aimed to evaluate the safety and efficacy of vosoritide in children with hypochondroplasia. We conducted a single-arm, phase 2, open-label trial at a single centre in the USA and enrolled 26 children with hypochondroplasia. The trial consists of a 6-month observation period to establish a baseline annualized growth velocity followed by a 12-month intervention period during which vosoritide is administered daily via subcutaneous injection at a dose of 15 μg/kg/day. The trial's co-primary endpoints included the incidence of adverse events and the change from baseline in age-sex standardized annualized growth velocity and height standardized deviation score (SDS) after 12 months of treatment. This trial is registered with ClinicalTrials.gov (NCT04219007). Twenty-four participants with a mean age of 5.86 years received vosoritide therapy. The first participant was enrolled on August 4, 2020, and the final participant completed the 18-month trial on September 8, 2023. Vosoritide was well tolerated with no treatment-related serious adverse events. Injection site reactions occurred in 83.3% of participants. No participants discontinued therapy due to an adverse event. Annualized growth velocity increased by 2.26 standard deviations (SD) and height SDS increased by 0.36 SD during the treatment period versus the observation period. Hypochondroplasia specific height SDS increased by 0.38 SD. There was a 1.81 cm/year increase in absolute annualized growth velocity. Vosoritide was safe and effective in increasing growth velocity in children with hypochondroplasia. Efficacy was similar to what has been reported in children with achondroplasia. This study was supported by an investigator-initiated grant from BioMarin Pharmaceutical.
gene therapies
2026-07-28 | HK1-LDHA axis feedback regulation promotes histone lactylation of Wnt5a and mediates prenatal acetaminophen-induced susceptibility to osteoarthritis in male offspring.
Acetaminophen is widely used during pregnancy but may cause developmental abnormalities in multiple systems in offspring. However, the effects of prenatal acetaminophen exposure (PAcE) on chondrodevelopment and long-term outcomes remain unclear. We administered 100 mg/kg per day of acetaminophen to rats on gestational days (GDs) 10-12 and treated fetal chondrocytes in vitro. In male PAcE offspring, cartilage matrix synthesis decreased and degradation increased at GD20 and postnatal week 12, with osteoarthritis (OA) susceptibility after running. Females exhibited only reduced matrix content at GD20. Mechanistically, acetaminophen inhibited the expression of hexokinase 1 (HK1) in chondrocytes under both normoxic and hypoxic conditions in vitro. However, HK1 inhibition induced feedback enhancement of the glycolytic only under hypoxic conditions, which increased lactic acid production and H3K18la lactylation levels in the Wnt5a promoter region, disrupting cartilage homeostasis. These effects were reversed by Wnt5a knockdown, HK1 overexpression, or LDHA knockdown. Finally, intra-articular adeno-associated virus-shWnt5a injection improved OA pathology in male PAcE offspring. In summary, PAcE upregulated H3K18la levels with Wnt5a through HK1-LDHA-mediated glycolytic feedback regulation, causing chondrodysplasia and increased OA susceptibility in male offspring, with sex differences. Our findings provide crucial insight into the hypoxia-dependent chondrotoxicity of PAcE, providing a reference for future research on fetal-derived OA. High H3K18la in the Wnt5a promoter region mediates PAcE-induced hypochondroplasia and susceptibility to adult OA in male offspring rats.
2026-05-05 | Rare Short Stature Disorders in Childhood: Future Implications for Treatment and Gene Therapy Options
Rare childhood short stature disorders such as Achondroplasia, Hypochondroplasia, ACAN syndrome, and Noonan Syndrome are primarily caused by specific genetic mutations that disrupt normal bone growth and development. Advances in molecular diagnostics have improved early detection, while emerging gene therapy approaches—including CRISPR-Cas9—offer promising future strategies to target the underlying genetic defects. The review aims to focus on rare genetically determined dwarfism syndromes, including conditions such as achondroplasia, hypochondroplasia, ACAN syndrome, and Noonan syndrome, with a focus on their underlying genetic causes, clinical features, and diagnostic approaches. The present review was conducted using secondary sources derived from existing academic literature, including peer-reviewed journal articles, books, and conference proceedings. Achondroplasia, the most common form of dwarfism, and hypochondroplasia are primarily caused by activating mutations in the FGFR3 gene, leading to impaired endochondral ossification. In contrast, ACAN mutations affect cartilage structure and growth plate function, while Noonan syndrome involves mutations in genes of the RAS/MAPK signaling pathway, such as PTPN11. Gene therapy, including genome editing technologies such as CRISPR-Cas9, offer a prospective avenue for causal treatment by targeting the underlying genetic defects. Early detection through advanced genetic screening, potentially even prenatally, may further enhance therapeutic outcomes. This review highlights the growing potential of gene-based interventions while emphasizing the need for continued research to translate these approaches into safe and effective clinical applications.
2024-02-10 | Relevance of Extending FGFR3 Gene Analysis in Osteochondrodysplasia to Non-Coding Sequences: A Case Report
Skeletal dysplasia, also called osteochondrodysplasia, is a category of disorders affecting bone development and children’s growth. Up to 552 genes, including fibroblast growth factor receptor 3 (FGFR3), have been implicated by pathogenic variations in its genesis. Frequently identified causal mutations in osteochondrodysplasia arise in the coding sequences of the FGFR3 gene: c.1138G>A and c.1138G>C in achondroplasia and c.1620C>A and c.1620C>G in hypochondroplasia. However, in some cases, the diagnostic investigations undertaken thus far have failed to identify the causal anomaly, which strengthens the relevance of the diagnostic strategies being further refined. We observed a Caucasian adult with clinical and radiographic features of achondroplasia, with no common pathogenic variant. Exome sequencing detected an FGFR3(NM_000142.4):c.1075+95C>G heterozygous intronic variation. In vitro studies showed that this variant results in the aberrant exonization of a 90-nucleotide 5′ segment of intron 8, resulting in the substitution of the alanine (Ala359) for a glycine (Gly) and the in-frame insertion of 30 amino acids. This change may alter FGFR3’s function. Our report provides the first clinical description of an adult carrying this variant, which completes the phenotype description previously provided in children and confirms the recurrence, the autosomal-dominant pathogenicity, and the diagnostic relevance of this FGFR3 intronic variant. We support its inclusion in routinely used diagnostic tests for osteochondrodysplasia. This may increase the detection rate of causal variants and therefore could have a positive impact on patient management. Finally, FGFR3 alteration via non-coding sequence exonization should be considered a recurrent disease mechanism to be taken into account for new drug design and clinical trial strategies.
2013-04-17 | Successful birth with preimplantation genetic diagnosis using single-cell allele-specific PCR and sequencing in a woman with hypochondroplasia due to FGFR3 mutation (c.1620C>A, p.N540K).
Hypochondroplasia (HCH) is an autosomal dominant inherited skeletal dysplasia, usually caused by a heterozygous mutation in the fibroblast growth factor receptor 3 gene (FGFR3). A 27-year-old HCH woman with a history of two consecutive abortions of HCH-affected fetuses visited our clinic for preimplantation genetic diagnosis (PGD). We confirmed the mutation in the proband (FGFR3:c.1620C>A, p.N540K), and established a nested allele-specific PCR and sequence analysis for PGD using single lymphocyte cells. We performed this molecular genetic analysis to detect the presence of mutation among 20 blastomeres from 18 different embryos, and selected 9 embryos with the wild-type sequence (FGFR3:c.1620C). A successful pregnancy was achieved through a frozen-thawed cycle and resulted in the full-term birth of a normal neonate. To the best of our knowledge, this is the first report of a successful pregnancy and birth using single-cell allele-specific PCR and sequencing for PGD in an HCH patient.
small molecules
2024-10-01 | 8519 Investigating the Role of Protein Inhibitor of Activated STAT1 (Pias1) in Growth Plate Chondrocyte Maturation
Abstract Disclosure: J. Baronas: None. U. Ahmed: None. J.N. Hirschhorn: None. N.E. Renthal: None. Development of growth plate chondrocytes is a complex process that involves a wide array of regulatory elements. Recently our laboratory conducted a genome wide CRISPR knockout (KO) screen of growth plate chondrocyte maturation to discover novel genes and gene networks in the proliferation and maturation of chondrocytes. Among targets uncovered is Protein Inhibitor of Activated STAT 1 (Pias1), an E3 SUMO ligase that plays a multi-faceted role in genetic regulation, driving post-translational modifications, directly binding to transcription factors, and functioning as a DNA-binding protein. While Pias1 has been shown to be involved in the regulation of many cellular processes across multiple tissues, its function in growth plate development and chondrocyte maturation has been previously unstudied. In our genome-wide screen, our laboratory identified that loss of Pias1 led to early maturation of chondrocytes. This project seeks to investigate the role of Pias1 in chondrocyte maturation and differentiation. We first developed a Pias1-KO chondrocyte cell line, observing upregulation of hypertrophic markers Cd200 and Col10a1 in KOs relative to control via qPCR, in addition to proliferative regulators IHH and Pth1R. Through Bulk-RNAseq of the same cell line, we identified additional chondrocyte markers as upregulated in KO, as well as osteoblast marker Sp7. Members of the HoxD family, regulators of limb development, were downregulated. Cell culture data suggests that loss of Pias1 leads to increased cell proliferation and increased matrix production, indicating dysregulation of multiple chondrocyte processes. Immunohistochemistry of micromass culture sections also suggests morphological differences between KO and control, with KO cells significantly larger in diameter. Early SUMO-1 profiling yields limited evidence of decreased global SUMOylation in KO cells, one possible mechanistic explanation for the observed dysregulation. Ongoing studies are focused on identifying specific SUMOylation targets of Pias1 in chondrocytes, analyzing proteomic differences in KO and control, seeking putative DNA-binding sites of Pias1, and observing in vivo murine Pias1-KO growth plates. Our findings suggest that PIAS1 plays a crucial role in the growth plate by prolonging growth and delaying terminal hypertrophy. Our study aims to provide a better understanding of the regulatory pathways involved in growth plate development and related phenotypes such as height, and contribute to the development of novel therapies for growth-related disorders, such as achondroplasia and hypochondroplasia. Presentation: 6/1/2024
2021-05-14 | Topical rapamycin for acanthosis nigricans in the Fitzpatrick IV/V adolescent population.
Dermatologically, FGFR3 mutations can lead to acanthosis nigricans (AN), epidermal nevi, and seborrheic keratosis. A recent case report found that topical rapamycin (sirolimus) can improve FGFR3-induced epidermal nevi with AN features in children, specifically with Fitzpatrick skin type (FST) I/II, and we would like to expand these findings to skin plaques with extensive AN-like features in the FST IV/V adolescent population. An 18-year-old female with FST IV/V and FGFR3-induced hypochondroplasia presented to our clinic with extensive AN-like plaques. Significant improvement with lightening and thinning of the plaques was observed after applying 1% topical rapamycin cream twice daily. Topical rapamycin should be considered as a treatment option for AN, particularly in FST IV/V adolescents with FGFR3-induced AN.
cell therapies
2024-02-08 | Prophylactic Intramedullary Rodding After Femoral Lengthening in Patients With Achondroplasia and Hypochondroplasia.
Femoral fracture after femoral lengthening in patients with achondroplasia and hypochondroplasia is a frequent complication, occurring in up to 30%. The purpose of this study is to demonstrate the effectiveness of prophylactic intramedullary rodding in preventing this complication. Multicenter retrospective study involving 86 femoral lengthening procedures in 43 patients with achondroplasia or hypochondroplasia. Forty-two femora (21 patients) were prophylactically managed with intramedullary Rush rodding after external fixation removal (11 females and 10 males, mean age 14.6 years) compared with 44 femora (22 patients) without prophylactic intramedullary rodding (13 females and 9 males, mean age 15.2 years). The mean amount of lengthening in the rodding group was 13.3 cm (52.6%) with an External Fixation Index of 25.8 days/cm; in patients without rodding was 14.3 cm (61.5%) and 24.5 days/cm, respectively. Seven cases (15.9%) without rodding developed fractures. Four of them required surgical correction due to displacement or shortening. Only 1 patient (2.4%) had fracture of the femur after prophylactic rodding, and surgery was not required. The incidence of femur fracture was significantly lower in the prophylactic rodding group compared with the nonrodding group (2.4% vs. 15.9%, respectively; P =0.034). There were no cases of infection or avascular necrosis. Prophylactic intramedullary rodding is a safe and effective method for preventing femoral fractures after femoral lengthening in patients with achondroplasia or hypochondroplasia. Level III-a retrospective comparative study.
2007-09-01 | Distraction Osteogenesis of the Lower Extremity in Patients With Achondroplasia/Hypochondroplasia Treated With Transplantation of Culture-Expanded Bone Marrow Cells and Platelet-Rich Plasma
Background: Longer treatment period in distraction osteogenesis (DO) of the lower extremity leads to more frequent complications. We have developed a new technique of transplantation of culture-expanded bone marrow cells (BMCs) and platelet-rich plasma (PRP) during DO to accelerate new bone formation. To assess the efficacy of this cell therapy, retrospective comparative study was conducted between the bones treated with BMC and PRP and the bones treated without BMC and PRP during DO in patients with achondroplasia (ACH) and hypochondroplasia (HCH). Methods: Fifty-six bones in 20 patients (ACH, 16; HCH, 4) that were lengthened in our hospital were divided into 2 groups. Twenty-four bones (femora, 12; tibiae, 12) in 11 patients (boys, 7; girls, 4) were treated with BMC and PRP transplantation (BMC-PRP group), whereas 32 bones (femora, 14; tibiae, 18) in 9 patients (boys, 3; girls, 6) did not undergo additional cell therapy (control group). The parameters, including the age at operation, the increase in length, and the healing index, were compared between the 2 groups. The clinical outcome was also compared between the femoral and tibial lengthenings. Results: Bone marrow cells (average number, ± SD, 3.2 ± 1.37 × 107 cells) and PRP (average platelet concentration ± SD, 2.36 ± 0.57 × 106 cells/μL) were transplanted. Although there were no significant differences in the age at operation and the length gained between the 2 groups, the average healing index of the BMC-PRP group (27.1 ± 6.89 d/cm) was significantly lower than that of the control group (36.2 ± 10.4 d/cm) (P = 0.0005). The femoral lengthening showed significantly faster healing than did the tibial lengthening in the BMC-PRP group (P = 0.0092). Conclusions: Transplantation of BMC and PRP shortened the treatment period by accelerating new bone regeneration during DO of the lower extremity in patients with ACH and HCH, especially in the femoral lengthening. Level of Evidence: Therapeutic studies, level III (retrospective comparative study).
1974-01-01 | Reconstitution of Cellular Immune Function in a Child with Thymic Aplasia by Foetal Thymus Grafting
Summary: A two-year-old, male non-identical twin with megacolon, hypochondroplasia of bone and absence of a thymus-dependent lymphoid population is described. No parathyroid dysfunction was detected and humoral immune function was intact, although only an IgM response was elicited by a thymus dependent antigen. Repeated grafting of unmatched thymus tissue from a human foetus of 12–16 weeks gestation has resulted in significant immunological re-constitution and clinical improvement.
proteins
2026-06-03 | Navepegritide: First Approval.
Navepegritide (YUVIWEL®) is a prodrug of C-type natriuretic peptide (CNP) developed by Ascendis Pharma for the treatment of achondroplasia and is being investigated for hypochondroplasia. Navepegritide is administered once weekly and designed to provide sustained release and continuous exposure of active CNP, which is needed to counteract the overactive fibroblast growth factor receptor 3 signaling in achondroplasia, resulting in improved growth velocity. Navepegritide recently received accelerated approval in the USA for increasing linear growth in paediatric patients aged ≥ 2 years with achondroplasia with open epiphyses. This article summarizes the milestones in the development of navepegritide leading to this first approval for achondroplasia.
2026-05-25 | Navepegritide: First Approval
DeclarationsAuthorship and Conflict of interest During the peer review process the manufacturer of the agent under review was offered an opportunity to comment on the article. Changes resulting from any comments received were made by the authors on the basis of scientific completeness and accuracy. Connie Kang is a salaried employee of Adis International Ltd/Springer Nature, and declares no relevant conflicts of interest. All authors contributed to this article and are responsible for its content.Ethics approval, Consent to participate, Consent to publish, Availability of data and material, Code availability Not applicable.
Additional information about this Adis Drug Review can be found here.
Abstract
Navepegritide (YUVIWEL®) is a prodrug of C-type natriuretic peptide (CNP) developed by Ascendis Pharma for the treatment of achondroplasia and is being investigated for hypochondroplasia. Navepegritide is administered once weekly and designed to provide sustained release and continuous exposure of active CNP, which is needed to counteract the overactive fibroblast growth factor receptor 3 signaling in achondroplasia, resulting in improved growth velocity. Navepegritide recently received accelerated approval in the USA for increasing linear growth in paediatric patients aged ≥ 2 years with achondroplasia with open epiphyses. This article summarizes the milestones in the development of navepegritide leading to this first approval for achondroplasia.
© Springer Nature Switzerland AG 2026
2026-01-01 | P237: Incidence of neurocognitive conditions in hypochondroplasia
Hypochondroplasia is one of several well-described skeletal dysplasias that occur along the FGFR3-spectrum. While individuals with hypochondroplasia generally present more mildly from a skeletal perspective than achondroplasia, an increased incidence of attention/hyperactivity concerns, learning, and intellectual disability as well as seizures, has been reported in this population. For counseling and screening purposes there is limited information on both risk of neurocognitive diagnoses and role of MRI as a predictor of neurocognitive outcomes.
2026-01-01 | P107: Experimental FGFR3 saturation mutagenesis and big-data integration identify 20 novel pathogenic variants in hypochondroplasia*
Hypochondroplasia is part of a spectrum of skeletal dysplasias caused by activating variants in FGFR3. Due to its clinical heterogeneity, diagnosis of hypochondroplasia, one of the most common FGFR3 disorders, is challenging without genetic confirmation.
2024-04-11 | Vosoritide treatment for children with hypochondroplasia: a phase 2 trial
Hypochondroplasia is a rare autosomal dominant skeletal dysplasia due to activating variants in FGFR3. It presents with disproportionate short stature with a wide range of clinical severity. There are currently no approved medications to treat short stature in children with hypochondroplasia. Vosoritide is a C-type natriuretic peptide analog that was recently approved for improving growth in children with achondroplasia. We aimed to evaluate the safety and efficacy of vosoritide in children with hypochondroplasia. We conducted a single-arm, phase 2, open-label trial at a single centre in the USA and enrolled 26 children with hypochondroplasia. The trial consists of a 6-month observation period to establish a baseline annualized growth velocity followed by a 12-month intervention period during which vosoritide is administered daily via subcutaneous injection at a dose of 15 μg/kg/day. The trial's co-primary endpoints included the incidence of adverse events and the change from baseline in age-sex standardized annualized growth velocity and height standardized deviation score (SDS) after 12 months of treatment. This trial is registered with ClinicalTrials.gov (NCT04219007). Twenty-four participants with a mean age of 5.86 years received vosoritide therapy. The first participant was enrolled on August 4, 2020, and the final participant completed the 18-month trial on September 8, 2023. Vosoritide was well tolerated with no treatment-related serious adverse events. Injection site reactions occurred in 83.3% of participants. No participants discontinued therapy due to an adverse event. Annualized growth velocity increased by 2.26 standard deviations (SD) and height SDS increased by 0.36 SD during the treatment period versus the observation period. Hypochondroplasia specific height SDS increased by 0.38 SD. There was a 1.81 cm/year increase in absolute annualized growth velocity. Vosoritide was safe and effective in increasing growth velocity in children with hypochondroplasia. Efficacy was similar to what has been reported in children with achondroplasia. This study was supported by an investigator-initiated grant from BioMarin Pharmaceutical.
gene therapies
2026-07-28 | HK1-LDHA axis feedback regulation promotes histone lactylation of Wnt5a and mediates prenatal acetaminophen-induced susceptibility to osteoarthritis in male offspring.
Acetaminophen is widely used during pregnancy but may cause developmental abnormalities in multiple systems in offspring. However, the effects of prenatal acetaminophen exposure (PAcE) on chondrodevelopment and long-term outcomes remain unclear. We administered 100 mg/kg per day of acetaminophen to rats on gestational days (GDs) 10-12 and treated fetal chondrocytes in vitro. In male PAcE offspring, cartilage matrix synthesis decreased and degradation increased at GD20 and postnatal week 12, with osteoarthritis (OA) susceptibility after running. Females exhibited only reduced matrix content at GD20. Mechanistically, acetaminophen inhibited the expression of hexokinase 1 (HK1) in chondrocytes under both normoxic and hypoxic conditions in vitro. However, HK1 inhibition induced feedback enhancement of the glycolytic only under hypoxic conditions, which increased lactic acid production and H3K18la lactylation levels in the Wnt5a promoter region, disrupting cartilage homeostasis. These effects were reversed by Wnt5a knockdown, HK1 overexpression, or LDHA knockdown. Finally, intra-articular adeno-associated virus-shWnt5a injection improved OA pathology in male PAcE offspring. In summary, PAcE upregulated H3K18la levels with Wnt5a through HK1-LDHA-mediated glycolytic feedback regulation, causing chondrodysplasia and increased OA susceptibility in male offspring, with sex differences. Our findings provide crucial insight into the hypoxia-dependent chondrotoxicity of PAcE, providing a reference for future research on fetal-derived OA. High H3K18la in the Wnt5a promoter region mediates PAcE-induced hypochondroplasia and susceptibility to adult OA in male offspring rats.
2026-05-05 | Rare Short Stature Disorders in Childhood: Future Implications for Treatment and Gene Therapy Options
Rare childhood short stature disorders such as Achondroplasia, Hypochondroplasia, ACAN syndrome, and Noonan Syndrome are primarily caused by specific genetic mutations that disrupt normal bone growth and development. Advances in molecular diagnostics have improved early detection, while emerging gene therapy approaches—including CRISPR-Cas9—offer promising future strategies to target the underlying genetic defects. The review aims to focus on rare genetically determined dwarfism syndromes, including conditions such as achondroplasia, hypochondroplasia, ACAN syndrome, and Noonan syndrome, with a focus on their underlying genetic causes, clinical features, and diagnostic approaches. The present review was conducted using secondary sources derived from existing academic literature, including peer-reviewed journal articles, books, and conference proceedings. Achondroplasia, the most common form of dwarfism, and hypochondroplasia are primarily caused by activating mutations in the FGFR3 gene, leading to impaired endochondral ossification. In contrast, ACAN mutations affect cartilage structure and growth plate function, while Noonan syndrome involves mutations in genes of the RAS/MAPK signaling pathway, such as PTPN11. Gene therapy, including genome editing technologies such as CRISPR-Cas9, offer a prospective avenue for causal treatment by targeting the underlying genetic defects. Early detection through advanced genetic screening, potentially even prenatally, may further enhance therapeutic outcomes. This review highlights the growing potential of gene-based interventions while emphasizing the need for continued research to translate these approaches into safe and effective clinical applications.
2024-02-10 | Relevance of Extending FGFR3 Gene Analysis in Osteochondrodysplasia to Non-Coding Sequences: A Case Report
Skeletal dysplasia, also called osteochondrodysplasia, is a category of disorders affecting bone development and children’s growth. Up to 552 genes, including fibroblast growth factor receptor 3 (FGFR3), have been implicated by pathogenic variations in its genesis. Frequently identified causal mutations in osteochondrodysplasia arise in the coding sequences of the FGFR3 gene: c.1138G>A and c.1138G>C in achondroplasia and c.1620C>A and c.1620C>G in hypochondroplasia. However, in some cases, the diagnostic investigations undertaken thus far have failed to identify the causal anomaly, which strengthens the relevance of the diagnostic strategies being further refined. We observed a Caucasian adult with clinical and radiographic features of achondroplasia, with no common pathogenic variant. Exome sequencing detected an FGFR3(NM_000142.4):c.1075+95C>G heterozygous intronic variation. In vitro studies showed that this variant results in the aberrant exonization of a 90-nucleotide 5′ segment of intron 8, resulting in the substitution of the alanine (Ala359) for a glycine (Gly) and the in-frame insertion of 30 amino acids. This change may alter FGFR3’s function. Our report provides the first clinical description of an adult carrying this variant, which completes the phenotype description previously provided in children and confirms the recurrence, the autosomal-dominant pathogenicity, and the diagnostic relevance of this FGFR3 intronic variant. We support its inclusion in routinely used diagnostic tests for osteochondrodysplasia. This may increase the detection rate of causal variants and therefore could have a positive impact on patient management. Finally, FGFR3 alteration via non-coding sequence exonization should be considered a recurrent disease mechanism to be taken into account for new drug design and clinical trial strategies.
2013-04-17 | Successful birth with preimplantation genetic diagnosis using single-cell allele-specific PCR and sequencing in a woman with hypochondroplasia due to FGFR3 mutation (c.1620C>A, p.N540K).
Hypochondroplasia (HCH) is an autosomal dominant inherited skeletal dysplasia, usually caused by a heterozygous mutation in the fibroblast growth factor receptor 3 gene (FGFR3). A 27-year-old HCH woman with a history of two consecutive abortions of HCH-affected fetuses visited our clinic for preimplantation genetic diagnosis (PGD). We confirmed the mutation in the proband (FGFR3:c.1620C>A, p.N540K), and established a nested allele-specific PCR and sequence analysis for PGD using single lymphocyte cells. We performed this molecular genetic analysis to detect the presence of mutation among 20 blastomeres from 18 different embryos, and selected 9 embryos with the wild-type sequence (FGFR3:c.1620C). A successful pregnancy was achieved through a frozen-thawed cycle and resulted in the full-term birth of a normal neonate. To the best of our knowledge, this is the first report of a successful pregnancy and birth using single-cell allele-specific PCR and sequencing for PGD in an HCH patient.
small molecules
2024-10-01 | 8519 Investigating the Role of Protein Inhibitor of Activated STAT1 (Pias1) in Growth Plate Chondrocyte Maturation
Abstract Disclosure: J. Baronas: None. U. Ahmed: None. J.N. Hirschhorn: None. N.E. Renthal: None. Development of growth plate chondrocytes is a complex process that involves a wide array of regulatory elements. Recently our laboratory conducted a genome wide CRISPR knockout (KO) screen of growth plate chondrocyte maturation to discover novel genes and gene networks in the proliferation and maturation of chondrocytes. Among targets uncovered is Protein Inhibitor of Activated STAT 1 (Pias1), an E3 SUMO ligase that plays a multi-faceted role in genetic regulation, driving post-translational modifications, directly binding to transcription factors, and functioning as a DNA-binding protein. While Pias1 has been shown to be involved in the regulation of many cellular processes across multiple tissues, its function in growth plate development and chondrocyte maturation has been previously unstudied. In our genome-wide screen, our laboratory identified that loss of Pias1 led to early maturation of chondrocytes. This project seeks to investigate the role of Pias1 in chondrocyte maturation and differentiation. We first developed a Pias1-KO chondrocyte cell line, observing upregulation of hypertrophic markers Cd200 and Col10a1 in KOs relative to control via qPCR, in addition to proliferative regulators IHH and Pth1R. Through Bulk-RNAseq of the same cell line, we identified additional chondrocyte markers as upregulated in KO, as well as osteoblast marker Sp7. Members of the HoxD family, regulators of limb development, were downregulated. Cell culture data suggests that loss of Pias1 leads to increased cell proliferation and increased matrix production, indicating dysregulation of multiple chondrocyte processes. Immunohistochemistry of micromass culture sections also suggests morphological differences between KO and control, with KO cells significantly larger in diameter. Early SUMO-1 profiling yields limited evidence of decreased global SUMOylation in KO cells, one possible mechanistic explanation for the observed dysregulation. Ongoing studies are focused on identifying specific SUMOylation targets of Pias1 in chondrocytes, analyzing proteomic differences in KO and control, seeking putative DNA-binding sites of Pias1, and observing in vivo murine Pias1-KO growth plates. Our findings suggest that PIAS1 plays a crucial role in the growth plate by prolonging growth and delaying terminal hypertrophy. Our study aims to provide a better understanding of the regulatory pathways involved in growth plate development and related phenotypes such as height, and contribute to the development of novel therapies for growth-related disorders, such as achondroplasia and hypochondroplasia. Presentation: 6/1/2024
2021-05-14 | Topical rapamycin for acanthosis nigricans in the Fitzpatrick IV/V adolescent population.
Dermatologically, FGFR3 mutations can lead to acanthosis nigricans (AN), epidermal nevi, and seborrheic keratosis. A recent case report found that topical rapamycin (sirolimus) can improve FGFR3-induced epidermal nevi with AN features in children, specifically with Fitzpatrick skin type (FST) I/II, and we would like to expand these findings to skin plaques with extensive AN-like features in the FST IV/V adolescent population. An 18-year-old female with FST IV/V and FGFR3-induced hypochondroplasia presented to our clinic with extensive AN-like plaques. Significant improvement with lightening and thinning of the plaques was observed after applying 1% topical rapamycin cream twice daily. Topical rapamycin should be considered as a treatment option for AN, particularly in FST IV/V adolescents with FGFR3-induced AN.
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Drug Discovery Landscape
4 orphan drug designations for Hypochondroplasia.
4 orphan drug designations for Hypochondroplasia.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
Infigratinib | small molecules | EMA | 2025-11-21 | — | BridgeBio Europe B.V. |
infigratinib | small molecules | FDA | 2025-06-03 | — | QED Therapeutics, Inc |
Vosoritide | peptides | EMA | 2024-12-13 | — | BioMarin International Limited |
vosoritide | peptides | FDA | 2023-08-01 | — | BioMarin Pharmaceutical Inc. |
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