Association between the neurofibromatosis-1 (NF1) locus and autism in the Japanese population

Autistic patients have a 100 to 190-fold increased risk of neurofibromatosis compared to the general population. This suggests that the two diseases may share a common etiological background. Recently, a new allele (or the six-repeat allele) of the (AAAT)_n repeat polymorphism in an Alu sequence in the neurofibromatosis-1 (NF1) gene was observed exclusively in severe autistic patients, not in controls, in Caucasians of French ancestry. This suggests a role of the NF1 gene in the development of autism. We investigated three microsatellite polymorphisms within the intron-27b and intron-38 of the NF1 region, including the (AAAT)_n and two (CA)n repeat polymorphisms, in Japanese subjects with autism (n = 74) and controls (n = 122). The six-repeat allele of the (AAAT)_n polymorphism was not found either in patients or controls, possibly indicating an ethnic difference in the polymorphism. However, significant differences were observed in the allele distributions of the (AAAT)_n and a (CA)_n, which were located at intron-27b, between patients and controls, although an association was not significant between autism and another polymorphism at intron-38. This may suggest an involvement of the NF1 locus in susceptibility to autism, although further investigations are recommended.