A linkage study between the GABAA beta2 and GABAA gamma2 subunit genes and major psychoses

BACKGROUND: Alterations of the gamma-aminobutyric acid (GABA) system have been implicated in the pathophysiology of major psychoses. OBJECTIVE: Restriction fragment length polymorphisms associated with the human gamma-aminobutyric acid type A (GABAA) beta2 and GABAA gamma2 subunit genes on chromosome 5q32-q35 were tested to determine whether they confer susceptibility to major psychoses. METHODS: Thirty-two schizophrenic families and 25 bipolar families were tested for linkage. Results: Nonparametric linkage (NPL) analysis performed by GENEHUNTER showed no significant NPL scores for both genes in schizophrenia (GABAA beta2: NPL narrow= -0.450; NPL broad= -0.808; GABAA gamma2: NPL narrow=0.177; NPL broad= -0.051) or bipolar disorder (GABAA beta2: NPL narrow=0.834; NPL broad=0.783; GABAA gamma2: NPL narrow= -0.159; NPL broad=0.070). CONCLUSION: Linkage analysis does not support the hypothesis that variants within the GABAA beta2 and GABAA gamma2 genes are significantly linked to major psychoses in a Portuguese population.