Absence of MeCP2 mutations in patients from the South Carolina autism project

The methyl-CpG binding protein 2 (MeCP2) gene has recently been identified as the gene responsible for Rett syndrome (RS), a pervasive developmental disorder considered by many to be one of the autism spectrum disorders. Most female patients with MeCP2 mutations exhibit the classic features of RS, including autistic behaviors. Most male patients with MeCP2 mutations exhibit moderate to severe developmental delay/mental retardation. Ninety nine patients from the South Carolina autism project (SCAP) were screened for MeCP2 mutations, including all 41 female patients from whom DNA samples were available plus the 58 male patients with the lowest scores on standard IQ tests and/or the Vineland Adaptive Behavior Scale. No pathogenic mutations were observed in these patients. One patient had the C582T variant, previously reported in the unaffected father of an RS patient. Two other patients had single nucleotide polymorphisms in the 3' UTR of the gene, G1470A and C1516G. These variants were seen in 12/82 and 1/178 phenotypically normal male controls, respectively. The findings from this and other studies suggest that mutations in the coding sequence of the MeCP2 gene are not a significant etiological factor in autism.