Genetic analysis of a case of chromosome 14q microdeletion

OBJECTIVE: To explore the genetic etiology of a child with autism, mental retardation and epilepsy. METHODS: Conventional G-banding chromosomal analysis was carried out. Chromosomal variation was also detected by single nucleotide polymorphism microarray (SNP array). Pathogenic mutations were screened by high-throughput sequencing and validated by Sanger sequencing. Pathologic significance of the candidate mutations was analyzed through search of database and literature review. RESULTS: No karyotypic abnormality was found with the child and his parents, while SNP array has detected a 460 kb deletion in the 14q11.2 region in the child. High-throughput and Sanger sequencing revealed a novel mutation of the NALCN gene in the child, in addition with a hemizygous mutation of the COL4A5 gene in the child and his mother. CONCLUSION: The 14q11.2 microdeletion and NALCN mutation may contribute to the autism, mental retardation and epilepsy in this child.