Alcohol use disorder and GABA B receptor gene polymorphisms in an Italian sample: haplotype frequencies, linkage disequilibrium and association studies.

Background: Alcohol use disorder (AUD) is a complex trait with genetic and environmental influences. Several gene variants have been associated with the risk for AUD, including genes encoding the sub-units of the γ-aminobutyric acid (GABA) receptors.
Aim: This study evaluated whether specific single nucleotide polymorphisms (SNPs) in genes encoding GABA _B receptor sub-units can be considered as candidates for the risk of AUD.
Subjects and Methods: Seventy-four AUD subjects and 128 Italian controls were genotyped for 10 SNPs in genes encoding GABA-B1 and GABA-B2 sub-units (GABBR1 and GABBR2). Allele, genotype, and haplotype frequencies were tested for the association with the AUD trait.
Results: A significant difference between AUD individuals and controls was observed at genotype level for rs2900512 of GABBR2 gene. The homozygous T/T genotype was not found in the controls, whereas it was over-represented in the AUD individuals. Under the recessive model (T/T vs C/T + C/C) this result was statistically significant, as well as the Odds Ratio for the association with the AUD trait.
Conclusions: The results provide preliminary data on the association between GABA _B receptor gene variation and risk of AUD. To confirm this finding, studies with larger samples and additional characterisation of the phenotypic AUD trait are required.