Serotonin transporter (5-HTT) and gamma-aminobutyric acid receptor subunit beta 3 (GABRB3) gene polymorphisms are not associated with autism in the IMGSA families by Maestrini, E, Lai, C, Marlow, A, Matthews, N, Wallace, S, Bailey, A, Cook, E, Weeks, D, Monaco, A, Consortium, IMGSA