Gamma-aminobutyric acid GABRA4, GABRE, and GABRQ receptor polymorphisms and risk for essential tremor

Some clinical and experimental data suggest a possible role of γ-aminobutyrate (GABA)-ergic mechanisms in the pathophysiology of essential tremor (ET). We studied the allelic and genotype frequencies of the single nucleotide polymorphisms, such as GABRA4-L26M (Leu26Met, rs2229940), GABRE-S102A (Ser26Ala, rs1139916), and GABRQ-I478F (Ile26Phe, rs3810651), in 200 patients with familial ET and 250 healthy controls using TaqMan genotyping. GABRA4-L26M, GABRE-S102A, and GABRQ-I478F genotype and allelic frequencies did not differ significantly between patients with ET and controls, and were unrelated to the age at onset of tremor or sex. The GABRQ-478F allele seemed to be related to improvement of tremor with ethanol use among men (odds ratio=2.32, 95% confidence interval=0.26–4.3, P=0.007, Pc=0.021). The results of this study suggest that the single nucleotide polymorphisms studied in the GABRA4, GABRE, and GABRQ genes are not related to the risk for familial ET.