Whole Exome Sequencing found a Novel Truncating Mutation within CNTNAP2 Gene in an Iranian Patient with Mental Retardation

Intellectual disability (ID) is a major health problem mostly with an unknown etiology, affecting 1–3% of the general population. Discovering the genetic cause of these cases is dramatically challenging. Nowadays, the next-generation sequencing (NGS) technology provides advantages for the genetic diagnosis of ID. Here, by the help of Whole exome sequencing, we report an Iranian family with a child having non-syndromic ID (NS-ID) with autistic behaviors and seizure. The results revealed a novel nonsense mutation (c.3283CGA>TGA) located in an autozygous region on chromosome 7, leading to an amino acid change to terminal codon (p.Arg1095*) in CNTNAAP2. The affected child was homozygous for the mutation and his parents were heterozygous as expected in autosomal recessive inheritance. In conclusion, our study identified a novel mutation in CNTNAAP2 gene, and showed that WES provides advantages for detecting novel ID associated variants and can greatly facilitate the genetic diagnosis of the disease.