1. Cholesteryl ester transfer protein activity may have a physiological effect on high-density lipoprotein levels.
2. We examined restriction fragment length polymorphisms associated with the cholesteryl ester transfer protein gene and the apolipoprotein AI gene in a group of 60 unrelated subjects selected from an initial survey of 5000 subjects on the basis of their high-density lipoprotein levels being high or low at the extremes of the distribution. The activities of cholesteryl ester transfer protein and lectithin:cholesterol acyltransferase (phosphatidylcholine-sterol acyltransferase, EC 188.8.131.52) were also determined. Analysis by selection of those with a low high-density lipoprotein cholesterol level (≤ 1.1 for males, ≤ 1.2 for females) gave 32 individuals with 24% B2 alleles. Selection of subjects with a high-density lipoprotein cholesterol level (≥ 2 mmol/l) gave 17 with 62% B2 alleles.
3. The group with low levels of high-density lipoprotein cholesterol had higher activity of cholesteryl ester transfer protein and significantly elevated triacylglycerol levels when compared with the group with high levels of high-density lipoprotein cholesterol.
4. A further significant finding was the correlation of the Msp1 restriction fragment length polymorphism detected by the apolipoprotein AI gene with lecithin:cholesterol acyltransferase activity.