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.