CETP deficiency appears to be a frequent cause of increased HDL levels in the population of Japan, possibly because of a founder effect. The results that we observed in heterozygotes suggest that CETP normally plays a part in the regulation of levels of HDL subclass 2. There was no evidence of premature atherosclerosis in the families with CETP deficiency. In fact, the lipoprotein profile of persons with CETP deficiency is potentially antiatherogenic and may be associated with an increased life span.

Plasma high density lipoproteins (HDL) are a negative risk factor for atherosclerosis. Increased HDL is sometimes clustered in families, but a genetic basis has never been clearly documented. The plasma cholesteryl ester transfer protein (CETP) catalyses the transfer of cholesteryl ester from HDL to other lipoproteins and therefore might influence HDL levels. Using monoclonal antibodies, we show that CETP is absent in two Japanese siblings who have markedly increased and enlarged HDL. Furthermore, they are homozygous for a point mutation in the 5'-splice donor site of intron 14 of the gene for CETP, a change that is incompatible with normal splicing of pre-messenger RNA. The results indicate that the family has an inherited deficiency of CETP due to a gene splicing defect, and illustrate the key role that CETP has in human HDL metabolism.

Genetic determinants of HDL cholesterol (HDL-C) levels in the general population are poorly understood. We previously described plasma cholesteryl ester transfer protein (CETP) deficiency due to an intron 14 G(+l)-to-A mutation(Intl4 A) in several families with very high HDL-C levels in Japan. Subjects with HDL-C 100 mg/dl (n = 130) were screened by PCR single strand conformational polymorphism analysis of the CETP gene. Two other mutations were identified by DNA sequencing or primer-mediated restriction map modification of PCR products: a novel intron 14 splice donor site mutation caused by a T insertion at position +3 from the exonl4/intronl4 boundary (Intl4 T) and a missense mutation (Asp'2 to Gly) within exon 15 (D442G).The Intl4 T mutation was only found in one family. However, the D442G and Intl4 A mutations were highly prevalent in subjects with HDL-C . 60 mg/dl, with combined allele frequencies of 9%, 12%, 21%, and 43% for HDL-C 60-79, 80-99, 100-119, and . 120 mg/dl, respectively. Furthermore, prevalences of the D442G and Intl4 A mutations were extremely high in a general sample of Japanese men (n = 236), with heterozygote frequencies of 7% and 2%, respectively. These two mutations accounted for about 10% of the total variance of HDL-C in this population. The phenotype in a genetic compound heterozygote (Intl4 T and Intl4 A) was similar to that of Intl4 A homozygotes (no detectable CETP and markedly increased HDL-C), indicating that the Intl4 T produces a null allele. In four D442G homozygotes, mean HDL-C levels (86±26 mg/dl) were lower than in Intl4 A homozygotes (158±35 mgldl), reflecting residual CETP activity in plasma. In 47 D442G heterozygotes, mean HDL-C levels were 91±23 mg/dl, similar to the level in D442G homozygotes, and significantly greater than mean HDL-C levels in Intl4 A heterozygotes (69±15 mg/dl). Thus, the D442G mutation acts differently to the null mutations A portion of this paper was presented at the Asian-Pacific Congress on coronary heart disease risk factor held in Hong Kong, January 1994.

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To investigate the clinical significance of circulating matrix metalloproteinases (MMPs) and their tissue inhibitos (TIMPs) in patients with premature coronary atheroscrelosis, we studied 53 consecutive male patients with angiographically defined premature (<65 years) and stable coronary artery disease. Plasma levels of MMP-2, MMP-3, MMP-9, TIMP-1, and TIMP-2 were determined in peripheral blood by a sandwich enzyme immunoassay, and the results were compared with those from 133 age-matched control males. There were significant differences in all the MMPs and TIMPs (p<0.001) between patients and controls. In the patient group, the levels of MMP-9 (mean +/- SD (ng/ml) 27.2 +/- 15.2/21.8 +/- 15.2) and TIMP-1 (130.4 +/- 55.7/94.5 +/- 26.3) were significantly higher, and the levels of MMP-2 (632.5 +/- 191.6/727.6 +/- 171.4), MMP-3 (53.1 +/- 31.2/79.6 +/- 29.9), and TIMP-2 (24.7 +/- 15.2/35.4 +/- 16.4) were significantly lower than those of controls. We found significant positive correlation between plasma MMP-9 levels and low-density lipoprotein (LDL)-cholesterol levels (Rs = 0.168, p = 0.022), and significant negative correlation between plasma MMP-9 levels and high-density lipoprotein (HDL)-cholesterol levels (Rs = -0.164, p = 0.026) by Spearman rank correlation test. In contrast, plasma MMP-2 (Rs = 0.181, p = 0.014) and MMP-3 (Rs = 0.260, p = 0.0004) levels were positively correlated with HDL-cholesterol levels. TIMP-2 levels were negatively correlated with total cholesterol (Rs = -0.197, p = 0.007) and LDL-cholesterol (Rs = -0.168, p=0.022) levels. These results suggest that the circulating levels of MMPs and TIMPs are altered in patients with premature coronary atherosclerosis and that plasma lipoprotein cholesterol levels correlate with these, possibly as a result of the lipoprotein-vessel wall interactions.

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From these data, we can assume that coronary artery stenosis detectable by angiography will occur after 17 and 25 years of age in male and female heterozygotes, respectively, and the treatment of heterozygotes with lipid-lowering drugs can be delayed until late adolescence. (Circulation 1989;79:225-332) F amilial hypercholesterolemia (FH) is a common autosomal dominant disorder caused by a mutation of the gene for the low-density lipoprotein (LDL) receptor.1 FH is frequently associated with premature coronary heart disease (CHD), and the rate of death from CHD among heterozygotes is several times higher than that among the general population.1-4 Homozygous patients do not usually survive to reach the age of 30,1,5 whereas the mean age at death for male and female heterozygotes is 54 and 65,4,6,7 respectively. There are no data, however, reporting when FH patients develop coronary heart disease documented by coronary angiography. The National Institutes of Health Consensus Development Conference on lowering cholesterol to prevent heart disease has recommended that strict dietary intervention is indicated for children with a blood cholesterol level above 200 mg/dl and that nonresponders should be considered for treatment with a lipid-lowering agent.