Relationships between the TaqI polymorphism of the dopamine D2 receptor and blood pressure in hyperglycaemic and normoglycaemic Chinese subjects

Background We have previously reported an association of the A2 allele of t he dopamine D2 receptor (DRD2) Taql polymorphism with increased blood press ure in normoglycaemic Chinese subjects, but conversely possibly with decrea sed indices of obesity. Hypertension is also a common feature of patients w ith type 2 diabetes, with up to 50% being hypertensive. Objective To compare the relationship between the DRD2 Taql polymorphism, b lood pressure and obesity in Chinese patients with and without fasting hype rglycaemia. method The DRD2 Taql polymorphism was determined by PCR-RFLP in 519 normogl ycaemic and 471 hyperglycaemic Chinese subjects, of whom 53.2 and 48.8% wer e hypertensive, respectively. Results In the normoglycaemic subjects there was a significant increase in mean arterial pressure (P=0.041) with increasing proportions of the A2 alle le, 95 +/- 16, 96 +/- 17 and 100 +/- 17 mmHg for the A1A1, A1A2 and A2A2 ge notypes, respectively. However, the relationship was not observed in the su bjects with fasting hyperglycaemia either in the total group or in the subg roup who were not receiving blood pressure-lowering medication (n=383, 97 /- 15, 98 +/- 14 and 97 +/- 15 mmHg, respectively). When the whole group wa s divided into those subjects obese by either body mass index or waist-to-h ip ratio (n=484) and those subjects not obese by both these criteria (n=506 ), the A1 allele (49.2 vs. 43.8%, P = 0.02) and A1 allele containing genoty pes (P=0.03) were more frequent in the obese subjects. Similar relationship s were seen in the normoglycaemic and hyperglycaemic groups separately, alt hough these did not reach significance. Conclusions In the normoglycaemic subjects, the A2 allele was associated wi th increased blood pressure and possibly lower indices of obesity, but in t he hyperglycaemic subjects only the possible association with obesity was n oted.