RESUMO
Objective: To analyze the clinical features and genetic etiology of a patient with developmental and epileptic encephalopathy. Methods: The clinical information and peripheral blood of the patient and their family members were collected before the whole exome sequencing analysis was performed and Sanger sequencing was employed to verify the potential variant. Results: The patient presented with epilepsy and cerebral palsy with his parents, brother, and sister being all healthy. Whole exome sequencing analysis revealed that the child carried the paternal c.823del (p. R275Gfs*31) heterozygous variant and the maternal c.2456del (p.V819Gfs*190) heterozygous variant of the CACNA1B gene. Pedigree verification found that the elder brother and amniotic fluid of fetus in womb carried the paternal c.823del heterozygous variant, and the elder sister carried the maternal c.2456del heterozygous variant, which conformed to the law of autosomal recessive inheritance. Neither of these two variants has been reported in the literature and has not been included in the Genomic Mutation Frequency Database (gnomAD); according to the American Academy of Medical Genetics and Genomics Variation Grading Guidelines (ACMG), both variants are classified as pathogenic variants (PVS1+PM2-Supporting + PM3). Conclusion: This study reported the first case of a child with neurodevelopmental disorder and epilepsy caused by a new compound heterozygous variant of the CACNA1B gene in China, clarified its genetic etiology, enriched the mutation spectrum and disease spectrum of CACNA1B gene, and provided a basis for prenatal diagnosis of the family.
RESUMO
BACKGROUND: Isolated focal dystonia (IFD) is a heterogeneous group of potentially invalidating movement disorders. The etiopathogenesis is complex, both genetic and environmental factors playing a role, but remains elusive. The CACNA1B gene codes for the N-type neuronal voltage-gated calcium channels CaV2.2, which may play a role in the development of some IFD. METHODS: We analyzed samples from the GENDYS cohort for mutations in CACNA1B gene, using targeted next-generation sequencing (NGS). RESULTS: The GENDYS cohort consists of 120 people with adult-onset IFD (cervical dystonia 47.5%, blepharospasm 47.2%, others 8.3%). Of these, 35% had subsequent topographical extension. Average age at onset was 42 and average disease durations 8 years. Targeted NGS revealed a novel frameshift mutation c.2291AGG > A, in exon 19, and a previously reported variant, c.6834T > G, in exon 47. CONCLUSION: Our findings suggest that disease-causing mutations in CACNA1B gene may be involved in the development of some adult-onset IFD. To our knowledge, this is the first study that identified a disease-causing CACNA1B gene mutation in association with adult-onset IFD.
