RARE DISEASE
X-linked intellectual disability, Najm type
X-linked intellectual disability, Najm type
X-linked intellectual disability, Najm type
Synonyms: MICPCH, X-linked intellectual disability-microcephaly-pontocerebellar hypoplasia syndrome
Synonyms: MICPCH, X-linked intellectual disability-microcephaly-pontocerebellar hypoplasia syndrome
Synonyms: MICPCH, X-linked intellectual disability-microcephaly-pontocerebellar hypoplasia syndrome
Drug discovery
22
papers
On emerging therapies
Overview
X-linked intellectual disability, Najm type is a rare neurodevelopmental disorder caused by pathogenic variants in the CASK gene (Xp11.4), leading to X-linked dominant inheritance. It is characterized by progressive microcephaly, cerebellar/pontine hypoplasia, severe intellectual disability, seizures, and motor impairments. Clinical spectrum ranges from mild deficits with congenital nystagmus to profound disability with cortical malformations. Diagnosis involves brain MRI showing simplified gyri and pontocerebellar atrophy, confirmed by molecular testing [1][2][11].
Categories: rare developmental anomalies during embryogenesis, rare genetic diseases, rare neurological diseases, rare ophthalmic disorders
Research Papers
22 drug discovery papers about X-linked intellectual disability, Najm type. Recent publications:
22 drug discovery papers about X-linked intellectual disability, Najm type. Recent publications:
categories:
Small molecules
small molecules
2026-03-15 | Cerebellar hypoplasia caused by calcium/calmodulin-dependent serine protein kinase deficiency.
Calcium/calmodulin-dependent serine protein kinase (CASK) is an X-linked multidomain scaffolding protein originally identified as an intracellular binding partner for Neurexins, a family of presynaptic cell-adhesion molecules. Loss-of-function mutations in CASK cause microcephaly with pontine and cerebellar hypoplasia (MICPCH), a severe neurodevelopmental disorder predominantly affecting females. Although CASK has been implicated in synaptic organization and transcriptional regulation, the mechanisms underlying the cerebellar hypoplasia have remained unsolved. Recent studies using genetically engineered mouse models and cerebellar granule cell cultures suggest that CASK is essential for neuronal survival rather than for initial patterning in the cerebellum. These works further reveal that X-chromosome inactivation-driven mosaicism influences the pathology of this disorder and that CASK deficiency activates c-Jun N-terminal kinase (JNK) signaling. In this review, we integrate these findings with the synaptic cell-adhesion biology, in relevance to Neurexin-CASK interaction and role of CASK in cerebellar neuron survival and discuss emerging therapeutic implications for CASK-related disorders.
2026-02-26 | Emerging role of KDM5C in X-linked intellectual disability based on human genetic data and zebrafish models.
Claes-Jensen syndrome is a rare X-linked syndromic neurodevelopmental disorder by pathogenic variants in lysine specific demethylase 5C (KDM5C), a lysine-specific histone demethylase. In this study, clinical evaluations were conducted in affected individuals and carrier females. X-chromosome inactivation (XCI) assays were performed to assess genotype-phenotype correlations. Functional studies evaluated variant effects on RNA transcription, protein expression, and stability. Zebrafish models were used for in vivo validation. RNA sequencing with KEGG and GO analyses identified dysregulated genes and pathways, further confirmed in zebrafish. Two novel KDM5C variants NM_004187.5:c.3019del and NM_004187.5:c.782-2A>T were identified in unrelated families with X-linked ID. Affected males presented with short stature, microcephaly, language delay, and intellectual disability, while carrier females showed milder features including learning difficulties and short stature. Skewed XCI in some carriers suggested a role in phenotypic variability. Both variants impair RNA transcription, protein expression and stability. Zebrafish models recapitulated neurodevelopmental and behavioral abnormalities. Transcriptomic analyses revealed disrupted antiviral and interferon-related signaling, implicating aberrant immune activation. Pharmacologic inhibition of the Toll-like receptor pathway ameliorated mutant phenotypes, highlighting neuroinflammation as a potential therapeutic target for KDM5C-related disorders. These findings expand the mutational spectrum of KDM5C-associated ID and uncover a novel pathogenic mechanism between KDM5C dysfunction, protein instability, and dysregulated inflammatory signaling.
2025-05-27 | Jun N-Terminal Kinase Inhibitor Suppresses CASK Deficiency-Induced Cerebellar Granular Cell Death in MICPCH Syndrome Model Mice.
Microcephaly with pontine and cerebellar hypoplasia (MICPCH) syndrome is a severe neurodevelopmental disorder caused by a deficiency in the X-linked gene calcium/calmodulin-dependent serine protein kinase (CASK). A better understanding of the role of CASK in the pathophysiology of neurodevelopmental disorders may provide insights into novel therapeutic and diagnostic strategies for MICPCH syndrome and other neurodegenerative diseases. To investigate this, we generated CASK knockout (KO) cerebellar granule (CG) cell culture from CASK floxed (CASKflox/flox) mice by infecting lentiviruses expressing codon-improved Cre recombinase (iCre). We performed RNA-sequencing (RNA-seq) on these cells and found that CASK-KO CG cells underwent apoptosis by activating intracellular Jun N-terminal kinase (JNK) signaling and upregulating reactive oxygen species (ROS)-related gene expression. We also performed mouse gait analysis and limb clasping behavior experiments on trans-heterozygous CASK-KO and Hprt-eGFP (CASK+/- HprteGFP/+) mice. The CASK+/- HprteGFP/+ mice exhibited cerebellar ataxic phenotypes as judged by the scores of these experiments compared to the CASK wild-type control (CASK+/+ HprteGFP/+) mice. Interestingly, the administration of the JNK inhibitor, JNK-IN-8, in CASK-KO CG cell cultures increased CG cell survival by reducing ROS generation. Moreover, injection of JNK-IN-8 into the cerebellum of CASK+/- HprteGFP/+ mice suppressed CG cell death and alleviated cerebellar ataxic phenotypes in vivo. In conclusion, JNK-IN-8 suppresses the cell death and activation of the ROS pathway in CASK-KO CG cells in both in vitro and in vivo models, suggesting its potential as a therapeutic strategy for cerebellar neurodegeneration in MICPCH syndrome.
2025-04-21 | JNK Inhibitor Suppresses CASK Deficiency-Induced Cerebellar Granular Cell Death in MICPCH Syndrome Model Mice
Microcephaly with pontine and cerebellar hypoplasia (MICPCH) syndrome is a severe neurodevelopmental disorder caused by a deficiency in the X-linked gene calcium/calmodulin-dependent serine protein kinase (CASK). A better understanding of the role of CASK in the pathophysiology of neurodevelopmental disorders may provide insights into novel therapeutic and diagnostic strategies for MICPCH syndrome and other neurodegenerative diseases. To investigate this, we generated CASK knockout (KO) cerebellar granule (CG) cell culture from CASK floxed (CASKflox/flox) mice by infecting lentiviruses expressing iCre. We performed RNA-sequencing (RNA-seq) on these cells and found that CASK-KO CG cells underwent apoptosis by activating intracellular Jun N-terminal kinase (JNK) signaling and upregulating reactive oxygen species (ROS) -related gene expression. We also performed mouse gait analysis and limb clasping behavior experiments on trans-heterozygous CASK-KO and Hprt-eGFP (CASK+/-HprteGFP/+) mice. The CASK+/-HprteGFP/+ mice exhibited cerebellar ataxic phenotypes as judged by the scores of these experiments compared to the CASK wild-type control (CASK+/-HprteGFP/+) mice. Interestingly, the administration of the JNK inhibitor, JNK-IN-8, in CASK-KO CG cell cultures increased CG cell survival by reducing ROS generation. Moreover, injection of JNK-IN-8 into the cerebellum of CASK+/-HprteGFP/+ mice suppressed CG cell death and alleviated cerebellar ataxic phenotypes in vivo. In conclusion, JNK-IN-8 suppresses the cell death and activation of ROS pathway in CASK-KO CG cells in both in vitro and in vivo models, suggesting its potential as a therapeutic strategy for cerebellar neurodegeneration in MICPCH syndrome.
2025-03-16 | Patients with Allan-Herndon-Dudley Syndrome (MCT8 Deficiency) Display Symptoms of Parkinsonism in Childhood and Respond to Levodopa/Carbidopa Treatment.
Patients with mutations in the monocarboxylate transporter 8 (MCT8, SLC16A2) suffer from X-linked recessive Allan-Herndon-Dudley syndrome (AHDS), which is characterized by developmental delay and a severe movement disorder. Current trials using thyroid hormone derivatives to overcome the transporter defect have failed to achieve patient-oriented therapeutic goals. Our aim was to define the type of movement disorder in AHDS in an observational cohort study and to investigate the causative role of the dopaminergic system. We present longitudinal clinical data from the DEEPTYPE registry of 11 patients with video documentation, standardized phenotyping, cerebrospinal fluid (CSF) analysis, neuroimaging data, and the treatment response to levodopa/carbidopa supplementation. Children presented with signs of childhood parkinsonism, including hypokinesia, hypomimia, inability to sit or stand, rigidity, dystonia, and autonomic dysfunction. CSF homovanillic acid concentrations were decreased (n = 12), suggesting an isolated dopamine pathway impairment. Seven out of 8 patients responded favorably to l-dopa/carbidopa supplementation and we did not observe any adverse drug reactions. AHDS is associated with childhood parkinsonism, which is linked with biochemical abnormalities of dopamine metabolism. It can be treated with l-dopa/carbidopa supplementation. However, further research is needed to elucidate the exact effect of MCT8 deficiency on dopamine metabolism. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
gene therapies
2024-04-01 | 363 A CRISPR/dCas9 Epigenetic Therapuetic Approach for CASK-Related MICPCH
OBJECTIVES/GOALS: CASK-related microcephaly with pontine and cerebellar hypoplasia (MICPCH) is a rare X-linked neurodevelopmental disorder caused by mutations in calcium/calmodulin-dependent serine protein kinase (CASK). We aim to rescue CASK expression via an CRISPR/dCas9 epigenetic therapeutic and create iPSC-based CASK relevant in vitro model systems. METHODS/STUDY POPULATION: As females have two X-chromosomes, disease causing mutations present with a 50/50 expression of mutant and wildtype, due to the mosaicism caused by random X-chromosome inactivation (XCI). This project will adapt an established CRISPR/dCas9 epigenetic approach to rescue expression from the silenced, wild-type CASK allele. We aim to accomplish this through testing different dCas9 orthologues and a guide RNA screen targeting the CASK promoter. Constructs will be tested for optimal targeting efficacy in vitro and assessed via RT-qPCR. Additionally, epigenetic modifications from our approach will be analyzed through bisulfite sequencing. We also aim to apply this epigenetic rescue technology in disease relevant cell lines and eventually in engineered patient mutation iPSC-derived neurons. RESULTS/ANTICIPATED RESULTS: Our results show the ability to target CASK and assess gene expression changes with CRISPR/dCas9 paired with an epigenetic modifier and transcriptional activator. Additionally, our fibroblast model with nonpathogenic single nucleotide polymorphisms within CASKallow for allele specific analysis of our targeted reactivation. We anticipate that following an increase of CASK expression, there would be a decrease in region specific promoter methylation. Further, with the identification of clinically described disease-causing point mutations that result in a loss of function of CASK protein, induction of the mutant sequence onto a healthy cell background will result in a similar reduction of CASK protein in our cell model. DISCUSSION/SIGNIFICANCE: This project will demonstrate the first therapeutic avenue for CASK-related MICPCH, and the potential to utilize targeted X-reactivation as a platform approach for X-linked disorders. Further, investigation of smaller dCas9 orthologues prepares our approach for future translational applications such as packaging into AAV for delivery.
2023-08-20 | Diverse Clinical Phenotypes of CASK-Related Disorders and Multiple Functional Domains of CASK Protein
CASK-related disorders are a form of rare X-linked neurological diseases and most of the patients are females. They are characterized by several symptoms, including microcephaly with pontine and cerebellar hypoplasia (MICPCH), epilepsy, congenital nystagmus, and neurodevelopmental disorders. Whole-genome sequencing has identified various mutations, including nonsense and missense mutations, from patients with CASK-related disorders, revealing correlations between specific mutations and clinical phenotypes. Notably, missense mutations associated with epilepsy and intellectual disability were found throughout the whole region of the CASK protein, while missense mutations related to microcephaly and MICPCH were restricted in certain domains. To investigate the pathophysiology of CASK-related disorders, research groups have employed diverse methods, including the generation of CASK knockout mice and the supplementation of CASK to rescue the phenotypes. These approaches have yielded valuable insights into the identification of functional domains of the CASK protein associated with a specific phenotype. Additionally, recent advancements in the AI-based prediction of protein structure, such as AlphaFold2, and the application of genome-editing techniques to generate CASK mutant mice carrying missense mutations from patients with CASK-related disorders, allow us to understand the pathophysiology of CASK-related disorders in more depth and to develop novel therapeutic methods for the fundamental treatment of CASK-related disorders.
2023-05-17 | Structural Analysis Implicates CASK-Liprin-α2 Interaction in Cerebellar Granular Cell Death in MICPCH Syndrome.
Microcephaly with pontine and cerebellar hypoplasia (MICPCH) syndrome is a neurodevelopmental disorder caused by the deficiency of the X-chromosomal gene CASK. However, the molecular mechanisms by which CASK deficiency causes cerebellar hypoplasia in this syndrome remain elusive. In this study, we used CASK knockout (KO) mice as models for MICPCH syndrome and investigated the effect of CASK mutants. Female CASK heterozygote KO mice replicate the progressive cerebellar hypoplasia observed in MICPCH syndrome. CASK KO cultured cerebellar granule (CG) cells show progressive cell death that can be rescued by co-infection with lentivirus expressing wild-type CASK. Rescue experiments with CASK deletion mutants identify that the CaMK, PDZ, and SH3, but not L27 and guanylate kinase domains of CASK are required for the survival of CG cells. We identify missense mutations in the CaMK domain of CASK derived from human patients that fail to rescue the cell death of cultured CASK KO CG cells. Machine learning-based structural analysis using AlphaFold 2.2 predicts that these mutations disrupt the structure of the binding interface with Liprin-α2. These results suggest that the interaction with Liprin-α2 via the CaMK domain of CASK may be involved in the pathophysiology of cerebellar hypoplasia in MICPCH syndrome.
proteins
2024-05-24 | CASK pathogenic variant which expands the clinical spectrum for MICPCH syndrome in an adult patient.
The CASK gene and its product protein kinase have been associated with microcephaly with pontine and cerebellar hypoplasia (MICPCH) syndrome and various other neurodevelopmental disorders. Clinical presentation is highly variable and generally includes intellectual disability, neurological disorders, and dysmorphic features, at a minimum. We present the case of one of the oldest known currently living patients with MICPCH syndrome with additional features not previously described in the literature (midface retrusion, macroglossia, dental crowding, adolescent-onset contractures at large joints, laxity at finger joints, and prominent wrist dystonia). Progressive hypertonicity throughout the patient's life has been managed with serial botulinum toxin injections. A comprehensive multimodal care team including physiatry, physical therapy, exercise therapy, and audiology has been assisting her with hearing deficits, communication skills, and mobility. This potentially expands the phenotype of MICPCH syndrome and provides information about the management of this condition into adulthood.
small molecules
2026-03-15 | Cerebellar hypoplasia caused by calcium/calmodulin-dependent serine protein kinase deficiency.
Calcium/calmodulin-dependent serine protein kinase (CASK) is an X-linked multidomain scaffolding protein originally identified as an intracellular binding partner for Neurexins, a family of presynaptic cell-adhesion molecules. Loss-of-function mutations in CASK cause microcephaly with pontine and cerebellar hypoplasia (MICPCH), a severe neurodevelopmental disorder predominantly affecting females. Although CASK has been implicated in synaptic organization and transcriptional regulation, the mechanisms underlying the cerebellar hypoplasia have remained unsolved. Recent studies using genetically engineered mouse models and cerebellar granule cell cultures suggest that CASK is essential for neuronal survival rather than for initial patterning in the cerebellum. These works further reveal that X-chromosome inactivation-driven mosaicism influences the pathology of this disorder and that CASK deficiency activates c-Jun N-terminal kinase (JNK) signaling. In this review, we integrate these findings with the synaptic cell-adhesion biology, in relevance to Neurexin-CASK interaction and role of CASK in cerebellar neuron survival and discuss emerging therapeutic implications for CASK-related disorders.
2026-02-26 | Emerging role of KDM5C in X-linked intellectual disability based on human genetic data and zebrafish models.
Claes-Jensen syndrome is a rare X-linked syndromic neurodevelopmental disorder by pathogenic variants in lysine specific demethylase 5C (KDM5C), a lysine-specific histone demethylase. In this study, clinical evaluations were conducted in affected individuals and carrier females. X-chromosome inactivation (XCI) assays were performed to assess genotype-phenotype correlations. Functional studies evaluated variant effects on RNA transcription, protein expression, and stability. Zebrafish models were used for in vivo validation. RNA sequencing with KEGG and GO analyses identified dysregulated genes and pathways, further confirmed in zebrafish. Two novel KDM5C variants NM_004187.5:c.3019del and NM_004187.5:c.782-2A>T were identified in unrelated families with X-linked ID. Affected males presented with short stature, microcephaly, language delay, and intellectual disability, while carrier females showed milder features including learning difficulties and short stature. Skewed XCI in some carriers suggested a role in phenotypic variability. Both variants impair RNA transcription, protein expression and stability. Zebrafish models recapitulated neurodevelopmental and behavioral abnormalities. Transcriptomic analyses revealed disrupted antiviral and interferon-related signaling, implicating aberrant immune activation. Pharmacologic inhibition of the Toll-like receptor pathway ameliorated mutant phenotypes, highlighting neuroinflammation as a potential therapeutic target for KDM5C-related disorders. These findings expand the mutational spectrum of KDM5C-associated ID and uncover a novel pathogenic mechanism between KDM5C dysfunction, protein instability, and dysregulated inflammatory signaling.
2025-05-27 | Jun N-Terminal Kinase Inhibitor Suppresses CASK Deficiency-Induced Cerebellar Granular Cell Death in MICPCH Syndrome Model Mice.
Microcephaly with pontine and cerebellar hypoplasia (MICPCH) syndrome is a severe neurodevelopmental disorder caused by a deficiency in the X-linked gene calcium/calmodulin-dependent serine protein kinase (CASK). A better understanding of the role of CASK in the pathophysiology of neurodevelopmental disorders may provide insights into novel therapeutic and diagnostic strategies for MICPCH syndrome and other neurodegenerative diseases. To investigate this, we generated CASK knockout (KO) cerebellar granule (CG) cell culture from CASK floxed (CASKflox/flox) mice by infecting lentiviruses expressing codon-improved Cre recombinase (iCre). We performed RNA-sequencing (RNA-seq) on these cells and found that CASK-KO CG cells underwent apoptosis by activating intracellular Jun N-terminal kinase (JNK) signaling and upregulating reactive oxygen species (ROS)-related gene expression. We also performed mouse gait analysis and limb clasping behavior experiments on trans-heterozygous CASK-KO and Hprt-eGFP (CASK+/- HprteGFP/+) mice. The CASK+/- HprteGFP/+ mice exhibited cerebellar ataxic phenotypes as judged by the scores of these experiments compared to the CASK wild-type control (CASK+/+ HprteGFP/+) mice. Interestingly, the administration of the JNK inhibitor, JNK-IN-8, in CASK-KO CG cell cultures increased CG cell survival by reducing ROS generation. Moreover, injection of JNK-IN-8 into the cerebellum of CASK+/- HprteGFP/+ mice suppressed CG cell death and alleviated cerebellar ataxic phenotypes in vivo. In conclusion, JNK-IN-8 suppresses the cell death and activation of the ROS pathway in CASK-KO CG cells in both in vitro and in vivo models, suggesting its potential as a therapeutic strategy for cerebellar neurodegeneration in MICPCH syndrome.
2025-04-21 | JNK Inhibitor Suppresses CASK Deficiency-Induced Cerebellar Granular Cell Death in MICPCH Syndrome Model Mice
Microcephaly with pontine and cerebellar hypoplasia (MICPCH) syndrome is a severe neurodevelopmental disorder caused by a deficiency in the X-linked gene calcium/calmodulin-dependent serine protein kinase (CASK). A better understanding of the role of CASK in the pathophysiology of neurodevelopmental disorders may provide insights into novel therapeutic and diagnostic strategies for MICPCH syndrome and other neurodegenerative diseases. To investigate this, we generated CASK knockout (KO) cerebellar granule (CG) cell culture from CASK floxed (CASKflox/flox) mice by infecting lentiviruses expressing iCre. We performed RNA-sequencing (RNA-seq) on these cells and found that CASK-KO CG cells underwent apoptosis by activating intracellular Jun N-terminal kinase (JNK) signaling and upregulating reactive oxygen species (ROS) -related gene expression. We also performed mouse gait analysis and limb clasping behavior experiments on trans-heterozygous CASK-KO and Hprt-eGFP (CASK+/-HprteGFP/+) mice. The CASK+/-HprteGFP/+ mice exhibited cerebellar ataxic phenotypes as judged by the scores of these experiments compared to the CASK wild-type control (CASK+/-HprteGFP/+) mice. Interestingly, the administration of the JNK inhibitor, JNK-IN-8, in CASK-KO CG cell cultures increased CG cell survival by reducing ROS generation. Moreover, injection of JNK-IN-8 into the cerebellum of CASK+/-HprteGFP/+ mice suppressed CG cell death and alleviated cerebellar ataxic phenotypes in vivo. In conclusion, JNK-IN-8 suppresses the cell death and activation of ROS pathway in CASK-KO CG cells in both in vitro and in vivo models, suggesting its potential as a therapeutic strategy for cerebellar neurodegeneration in MICPCH syndrome.
2025-03-16 | Patients with Allan-Herndon-Dudley Syndrome (MCT8 Deficiency) Display Symptoms of Parkinsonism in Childhood and Respond to Levodopa/Carbidopa Treatment.
Patients with mutations in the monocarboxylate transporter 8 (MCT8, SLC16A2) suffer from X-linked recessive Allan-Herndon-Dudley syndrome (AHDS), which is characterized by developmental delay and a severe movement disorder. Current trials using thyroid hormone derivatives to overcome the transporter defect have failed to achieve patient-oriented therapeutic goals. Our aim was to define the type of movement disorder in AHDS in an observational cohort study and to investigate the causative role of the dopaminergic system. We present longitudinal clinical data from the DEEPTYPE registry of 11 patients with video documentation, standardized phenotyping, cerebrospinal fluid (CSF) analysis, neuroimaging data, and the treatment response to levodopa/carbidopa supplementation. Children presented with signs of childhood parkinsonism, including hypokinesia, hypomimia, inability to sit or stand, rigidity, dystonia, and autonomic dysfunction. CSF homovanillic acid concentrations were decreased (n = 12), suggesting an isolated dopamine pathway impairment. Seven out of 8 patients responded favorably to l-dopa/carbidopa supplementation and we did not observe any adverse drug reactions. AHDS is associated with childhood parkinsonism, which is linked with biochemical abnormalities of dopamine metabolism. It can be treated with l-dopa/carbidopa supplementation. However, further research is needed to elucidate the exact effect of MCT8 deficiency on dopamine metabolism. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
gene therapies
2024-04-01 | 363 A CRISPR/dCas9 Epigenetic Therapuetic Approach for CASK-Related MICPCH
OBJECTIVES/GOALS: CASK-related microcephaly with pontine and cerebellar hypoplasia (MICPCH) is a rare X-linked neurodevelopmental disorder caused by mutations in calcium/calmodulin-dependent serine protein kinase (CASK). We aim to rescue CASK expression via an CRISPR/dCas9 epigenetic therapeutic and create iPSC-based CASK relevant in vitro model systems. METHODS/STUDY POPULATION: As females have two X-chromosomes, disease causing mutations present with a 50/50 expression of mutant and wildtype, due to the mosaicism caused by random X-chromosome inactivation (XCI). This project will adapt an established CRISPR/dCas9 epigenetic approach to rescue expression from the silenced, wild-type CASK allele. We aim to accomplish this through testing different dCas9 orthologues and a guide RNA screen targeting the CASK promoter. Constructs will be tested for optimal targeting efficacy in vitro and assessed via RT-qPCR. Additionally, epigenetic modifications from our approach will be analyzed through bisulfite sequencing. We also aim to apply this epigenetic rescue technology in disease relevant cell lines and eventually in engineered patient mutation iPSC-derived neurons. RESULTS/ANTICIPATED RESULTS: Our results show the ability to target CASK and assess gene expression changes with CRISPR/dCas9 paired with an epigenetic modifier and transcriptional activator. Additionally, our fibroblast model with nonpathogenic single nucleotide polymorphisms within CASKallow for allele specific analysis of our targeted reactivation. We anticipate that following an increase of CASK expression, there would be a decrease in region specific promoter methylation. Further, with the identification of clinically described disease-causing point mutations that result in a loss of function of CASK protein, induction of the mutant sequence onto a healthy cell background will result in a similar reduction of CASK protein in our cell model. DISCUSSION/SIGNIFICANCE: This project will demonstrate the first therapeutic avenue for CASK-related MICPCH, and the potential to utilize targeted X-reactivation as a platform approach for X-linked disorders. Further, investigation of smaller dCas9 orthologues prepares our approach for future translational applications such as packaging into AAV for delivery.
2023-08-20 | Diverse Clinical Phenotypes of CASK-Related Disorders and Multiple Functional Domains of CASK Protein
CASK-related disorders are a form of rare X-linked neurological diseases and most of the patients are females. They are characterized by several symptoms, including microcephaly with pontine and cerebellar hypoplasia (MICPCH), epilepsy, congenital nystagmus, and neurodevelopmental disorders. Whole-genome sequencing has identified various mutations, including nonsense and missense mutations, from patients with CASK-related disorders, revealing correlations between specific mutations and clinical phenotypes. Notably, missense mutations associated with epilepsy and intellectual disability were found throughout the whole region of the CASK protein, while missense mutations related to microcephaly and MICPCH were restricted in certain domains. To investigate the pathophysiology of CASK-related disorders, research groups have employed diverse methods, including the generation of CASK knockout mice and the supplementation of CASK to rescue the phenotypes. These approaches have yielded valuable insights into the identification of functional domains of the CASK protein associated with a specific phenotype. Additionally, recent advancements in the AI-based prediction of protein structure, such as AlphaFold2, and the application of genome-editing techniques to generate CASK mutant mice carrying missense mutations from patients with CASK-related disorders, allow us to understand the pathophysiology of CASK-related disorders in more depth and to develop novel therapeutic methods for the fundamental treatment of CASK-related disorders.
2023-05-17 | Structural Analysis Implicates CASK-Liprin-α2 Interaction in Cerebellar Granular Cell Death in MICPCH Syndrome.
Microcephaly with pontine and cerebellar hypoplasia (MICPCH) syndrome is a neurodevelopmental disorder caused by the deficiency of the X-chromosomal gene CASK. However, the molecular mechanisms by which CASK deficiency causes cerebellar hypoplasia in this syndrome remain elusive. In this study, we used CASK knockout (KO) mice as models for MICPCH syndrome and investigated the effect of CASK mutants. Female CASK heterozygote KO mice replicate the progressive cerebellar hypoplasia observed in MICPCH syndrome. CASK KO cultured cerebellar granule (CG) cells show progressive cell death that can be rescued by co-infection with lentivirus expressing wild-type CASK. Rescue experiments with CASK deletion mutants identify that the CaMK, PDZ, and SH3, but not L27 and guanylate kinase domains of CASK are required for the survival of CG cells. We identify missense mutations in the CaMK domain of CASK derived from human patients that fail to rescue the cell death of cultured CASK KO CG cells. Machine learning-based structural analysis using AlphaFold 2.2 predicts that these mutations disrupt the structure of the binding interface with Liprin-α2. These results suggest that the interaction with Liprin-α2 via the CaMK domain of CASK may be involved in the pathophysiology of cerebellar hypoplasia in MICPCH syndrome.
proteins
2024-05-24 | CASK pathogenic variant which expands the clinical spectrum for MICPCH syndrome in an adult patient.
The CASK gene and its product protein kinase have been associated with microcephaly with pontine and cerebellar hypoplasia (MICPCH) syndrome and various other neurodevelopmental disorders. Clinical presentation is highly variable and generally includes intellectual disability, neurological disorders, and dysmorphic features, at a minimum. We present the case of one of the oldest known currently living patients with MICPCH syndrome with additional features not previously described in the literature (midface retrusion, macroglossia, dental crowding, adolescent-onset contractures at large joints, laxity at finger joints, and prominent wrist dystonia). Progressive hypertonicity throughout the patient's life has been managed with serial botulinum toxin injections. A comprehensive multimodal care team including physiatry, physical therapy, exercise therapy, and audiology has been assisting her with hearing deficits, communication skills, and mobility. This potentially expands the phenotype of MICPCH syndrome and provides information about the management of this condition into adulthood.
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