Serotonin transporter (5-HTT) and gamma-aminobutyric acid receptor subunitbeta 3 (GABRB3) gene polymorphisms are not associated with autism in the IMGSA families

Previous studies have suggested that the serotonin transporter (5-HTT) gene and the gamma-aminobutyric acid receptor subunit beta 3 (GABRB3) gene, or other genes in the 15q11-q13 region, are possibly involved in susceptibilit y to autism, To test this hypothesis we performed an association study on t he collection of families from the International Molecular Genetic Study of Autism (IMGSA) Consortium, using the transmission disequilibrium test, Two polymorphisms in the 5-HTT gene (a functional insertion-deletion polymorph ism in the promoter and a variable number tandem repeat in the second intro n) were examined in 90 families comprising 174 affected individuals. Furthe rmore, seven microsatellite markers spanning the 15q11-q13 region were stud ied in 94 families with 182 affected individuals. No significant evidence o f association or linkage was found at any of the markers tested, indicating that the 5-HTT and the GABRB3 genes are unlikely to play a major role in t he aetiology of autism in our family data set. (C) 1999 Wiley-Liss, Inc.