Association of two apolipoprotein A-I gene MspI polymorphisms with high density lipoprotein (HDL)-cholesterol levels and indices of obesity in selected healthy Chinese subjects and in patients with early-onset type 2 diabetes

Abstract

OBJECTIVE: Previous studies have reported associations between two apolipoprotein A-I (apoA-I) gene MspI polymorphisms (G-75A and C83T) and high density lipoprotein (HDL)-cholesterol and/or apoA-I levels, but have not investigated the relationship with obesity. METHODS: We determined the distribution of these polymorphisms in 482 early-onset (< or = 40 years) Type 2 Chinese diabetics and 167 Chinese selected healthy controls. RESULTS: The -75A and 83T allele frequencies were similar in the diabetic and healthy subjects. In the healthy control subjects, HDL-cholesterol levels were significantly higher in the AA homozygotes than in the GG/GA carriers (1.74 +/- 0.58 vs. 1.45 +/- 0.58 mmol/l, P<0.001). Furthermore, analyses showed a significant relationship between increasing HDL-cholesterol tertiles and the AA genotype frequency in the selected healthy subjects (3.6, 8.9 and 16.1%, P=0.026). For the C83T polymorphism, healthy male CT carriers had higher HDL-cholesterol levels than CC homozygotes (1.71 +/- 0.57 vs. 1.25 +/- 0.30 mmol/l, P=0.001), but this was not found in females. No relationship between these polymorphisms and lipid levels was found in the diabetics, who had a more adverse lipid profile than the selected controls. In the diabetics, but not the controls, in CT carriers compared to CC homozygotes there were lower levels of body mass index (BMI; 23.8 +/- 3.9 vs. 25.4 +/- 4.7 kg/m2, P=0.048) and waist-to-height ratio (0.49 +/- 0.06 vs. 0.52 +/- 0.07, P=0.023), and this relationship was supported by tertile analysis. CONCLUSIONS: The -75AA genotype was associated with higher HDL-cholesterol levels in the selected healthy, but not diabetic, subjects. The 83T allele was associated with greater indices of obesity in the diabetic patients, and with higher HDL-cholesterol in heterozygous healthy male subjects.