Association of deletion allele of insertion/deletion polymorphism in α2B adrenoceptor gene and hypertension with or without type 2 diabetes mellitus

BACKGROUND Vascular α2B-adrenoreceptors have the potential to increase blood pressure by mediating vasoconstriction. A nine-nucleotide deletion in the receptor enhances vasoconstriction and exacerbates hypertension. The aim of this study was to determine the association between insertion/deletion (I/D) polymorphism of the α2B-adrenoceptor and hypertension with and without diabetes. METHODS The study was carried out in 35 hypertensive patients with diabetes, 35 hypertensive patients without diabetes, and 30 healthy controls. Clinical data, blood lipid profiles, and I/D polymorphism were assessed. RESULTS Hypertensive patients were significantly older, with significantly higher systolic/diastolic blood pressures and worse plasma lipid profiles than controls. The frequency of the DD genotype was significantly higher in both hypertensive patients with (77.14%, P < 0.01) and without (71.43%, P < 0.05) diabetes versus controls (40%). Also, the D allele was significantly more common in both hypertensive patients with (84.29%, P < 0.01) and without (80%, P < 0.05) diabetes versus controls (58.33%). Hypertensive patients were more likely to have the D allele with (3.83-fold) and without (2.85-fold) diabetes. The frequencies of the DD genotype and the D allele were not significantly (P > 0.05) different between the patient groups. The DD genotype was associated with significantly lower high-density lipoprotein (P = 0.001) and significantly higher low-density lipoprotein (P = 0.017) levels versus the II and ID genotypes in the hypertensive group without diabetes. CONCLUSION A marked and statistically significant association between DD genotype and D allele of I/D polymorphism in the α2B-adrenoceptor gene may be a risk factor for hypertension ± diabetes. The association between the DD genotype and dyslipidemia may partially explain its role in precipitating hypertension.