Abstract:
Background and aims: Hyperalphalipoproteinemia (HALP) or high HDL level represents a common disorder from various genetic and environmental etiologies. In Japan, HALP is primarily caused by mutations of the cholesteryl ester transfer protein (CETP) gene resulting in decreased or no activity of CETP. Outside Japan, however, the cause of HALP and the prevalence of CETP deficiency are unknown. Objectives: To determine CETP activity and the prevalence of CETP deficiency in Thai people who have very high levels of HDL. Materials and methods: Thirty-eight subjects with HDL-cholesterol levels higher than 100 mg/dL, and age- and sex-matched controls were recruited from an outpatient clinic. Secondary causes of HALP were excluded. The medical history, physical examination, signs of abnormal lipid accumulation and atherosclerotic vascular diseases were examined. CETP activity was measured by fluorescence method. Results: In the HALP group, all except one case were female. The mean age was 56 +- 2 year in both groups. Eleven subjects had corneal arcus in contrast to six subjects in the control group (p = 0.17). One subject in each group had a history of cerebrovascular disease. The mean total cholesterol and HDL levels were higher in the HALP group (total cholesterol 256 +- 6 vs 234 +- 6 : p< 0.05 and HDL level 117 +- 3 vs 64 +- 3 : p< 0.001). Unexpectedly, the mean triglyceride (TG) levels were lower in the HALP group (73 +- 6 vs 137 +- 13 : p<0.001). CETP activity was significantly lower in the HALP group (34.1 +- 3.9 vs 43.7 +- 2.6 pmol/micro L/hr: p<0.05). Twenty subjects in the HALP group (53%) had the CETP activity less than 75% of the mean CETP activity in the control group indicating CETP deficiency, including three subjects with undetectable activity. There was an inverse correlation between HDL levels and CETP activity in both groups (r = - 0.29 ; p<0.05). In addition, there was an inverse correlation between HDL and TG levels (r = - 0.62 ; p<0.001). Conclusion: In Thai population, HALP was found almost exclusively in women, and CETP activity was decreased in about half of these patients