Nonsyndromic intellectual disability with novel heterozygous mutation and epilepsy.

mutations are primarily associated with a variety of epilepsy syndromes. Recently, has been reported as a gene responsible for nonsyndromic intellectual disability or autism spectrum disorders. Here, we present a case of a 12-year-old girl with nonsyndromic intellectual disability who exhibited a heterozygous de novo missense mutation in . She developed seizures during the course of illness. This case suggests that the phenotype of patients with heterozygous mutations can be variable.