Association between a GABRB3 polymorphism and autism

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Abstract
Autistic disorder (OMIM 209850) is a disease with a significant genetic component of a complex nature.1 Cytogenetic abnormalities in the Prader-Willi/Angelman syndrome critical region (15q11–13) have been described in several individuals with autism.1 For this reason, markers across this region have been screened for evidence of linkage and association, and a marker (155CA-2) in the γ-aminobutyric acid type-A receptor β3 subunit gene (GABRB3) has been associated in one study2 but not others.3–5 We completed an association analysis with 155CA-2 using the transmission disequilibrium test (TDT) in a set of 80 autism families (59 multiplex and 21 trios). We also used four additional markers (69CA, 155CA-1, 85CA, and A55CA-1) localized within 150 kb of 155CA-2. The use of multi-allelic TDT (MTDT) (P < 0.002), as well as the TDT (P < 0.004), demonstrated an association between autistic disorder and 155CA-2 in these families. Meiotic segregation distortion could be excluded as a possible cause for these results since no disequilibrium was observed in unaffected siblings. These findings support a role for genetic variants within the GABA receptor gene complex in 15q11–13 in autistic disorder.