Peripheral atherosclerosis in familial hypercholesterolaemia

Unlike coronary artery disease, peripheral atherosclerosis is considered to be infrequent in heterozygous familial hypercholesterolaemia. The authors studied 20 consecutive asymptomatic familial hypercholesterolaemic patients and an age- and sex-matched control group of consecutive normolipidaemic and asymptomatic patients admitted to the hospital for elective non-vascular surgery. The patients and the controls were studied non-invasively by measuring the ankle-arm systolic blood pressure ratio at rest. Peripheral atherosclerosis was common in this study population in contrast to the control group: an abnormal (less than 0.97) pressure ratio was found in 13 patients (65%) in the study group but in only one person in the control group. Eight out of 20 patients had coronary artery disease, and seven of them had an asymptomatic concomitant peripheral artery disease. Neither the classical risk factors, i.e. age, smoking, obesity, hypertension and glucose intolerance, nor serum lipid or lipoprotein status or the parameters of cholesterol metabolism correlated with peripheral atherosclerosis. It is concluded that atherosclerosis in familial hypercholesterolaemia is a multilevel disease that frequently affects also the peripheral arteries.

Absorption and metabolism of cholesterol in familial hypercholesterolaemia

1. The present study investigated the role of intestinal cholesterol absorption in the regulation of cholesterol metabolism and serum lipoprotein levels in 22 patients with heterozygous familial hypercholesterolaemia on low to normal cholesterol intake. 2. The results showed that the higher the dietary cholesterol absorption, the lower was the overall synthesis of cholesterol. Efficient cholesterol absorption actually reduced the elimination of cholesterol as faecal neutral sterols but not consistently as bile acids. 3. In multifactorial analysis, body mass index and dietary plant sterols were negatively associated with cholesterol absorption, but were unrelated to cholesterol synthesis. 4. Fractional cholesterol absorption was related only to the serum very-low-density triacylglycerol level. It was not associated with the total or low-density lipoprotein cholesterol levels. On the other hand, cholesterol synthesis was significantly associated with the serum concentrations of very-low-density lipoprotein and intermediate-density lipoprotein cholesterol and triacylglycerols, and with those of low-density lipoprotein triacylglycerols. 5. In conclusion, dietary cholesterol absorption is an essential regulator of cholesterol homoeostasis in familial hypercholesterolaemia, even in patients on low cholesterol intake.

Effects of acipimox and cholestyramine on serum lipoproteins, non-cholesterol sterols and cholesterol absorption and elimination

The hypolipidaemic and metabolic effects of cholestyramine combined with acipimox or placebo have been evaluated in a double-blind ninety-day study in 18 patients with xanthomatous familial hypercholesterolaemia. Serum LDL-cholesterol was reduced by 35% in the cholestyramine group and 39% in the acipimoxcholestyramine group. The latter treatment increased the HDL-cholesterol level. Serum VLDL-cholesterol and triglyceride concentrations were unchanged. Cholesterol absorption efficiency was significantly reduced, and bile acid synthesis and faecal cholesterol elimination in both groups were increased. The metabolic changes were similar in the two treatment groups, but the increase in faecal neutral sterol excretion was significant only when acipimox was added. The serum cholesterol precursor sterol contents were similarly increased during the two treatments, indicating enhancement of endogenous cholesterol synthesis. The decrease in cholesterol absorption and the increase in neutral sterol excretion were more pronounced in subjects with greater than 30% than in those with less than 30% reduction in LDL-cholesterol. The changes in serum total and LDL-cholesterol levels and cholesterol metabolism were not related to apoE phenotype, but the increase in HDL-cholesterol was higher in E4 then in E3 subjects.

Serum noncholesterol sterols related to cholesterol metabolism in familial hypercholesterolemia

Serum cholesterol precursor levels and plant sterol were related to parameters of cholesterol metabolism in 22 patients with heterozygous familial hypercholesterolemia. The serum levels of cholesterol precursor sterols were inversely related to fractional absorption of dietary cholesterol and subsequently positively to overall cholesterol synthesis. The serum plant sterol levels, on the contrary, were significantly associated with fractional cholesterol absorption and negatively with overall cholesterol synthesis. These results were confirmed also with multivariate analyses. Fecal lanosterol, a cholesterol precursor, was related positively to cholesterol synthesis measured by sterol balance and serum precursors and negatively to serum plant sterols. The serum precursor and plant sterol levels were inversely significantly related to each other, indicating that the higher cholesterol absorption efficiency the higher are the serum plant sterol levels and the lower the precursor sterol contents and the overall cholesterol synthesis.

A longitudinal study of cholesterol metabolism in familial hypercholesterolemia

Sterol balance studies were performed in 11 patients with familial hypercholesterolemia before and after a 15-year follow-up exactly under the same conditions to evaluate whether ageing exerts any changes on serum lipids and cholesterol metabolism. No significant intraindividual variation could be observed in serum lipids, bile acid and cholesterol synthesis and cholesterol excretion as neutral sterols and no age-related association could be observed in these parameters.

Identification of a deletion in the LDL receptor gene. A Finnish type of mutation

A cDNA probe for the low density lipoprotein (LDL) receptor gene was used to screen DNA samples from 52 unrelated Finnish patients with the heterozygous form of familial hypercholesterolemia (FH) and 51 healthy controls. Southern blot analysis using the restriction enzyme PvuII revealed an abnormal 11 kb (kilo base-pair) restriction fragment in 16 (31%) of the patients but none of the controls. A more detailed restriction enzyme analysis of the DNA from patients revealed a mutation which apparently is due to an 8 kb deletion extending from intron 15 to exon 18 of the LDL receptor gene. Co-segregation of FH with the mutated gene was demonstrated in three families. These data are consistent with a 'founder gene effect' and support the assumption that recombinant DNA methods may have great impact on the diagnostics of FH in genetically homogeneous populations.

Mortality and cholesterol metabolism in familial hypercholesterolemia. Long-term follow-up of 96 patients

The aim of this prospective study was to explore the association of different prognostic factors including parameters of cholesterol metabolism with coronary morbidity and mortality in a study group of 96 patients who were heterozygous for familial hypercholesterolemia. During a 15-year follow-up period, 27% of the patients (44% of the men and 10% of the women, p less than 0.01) died from coronary disease, and an additional 4% died of noncoronary causes. Of the baseline characteristics, male gender, previous myocardial infarction, and smoking were the classical risk factors significantly associated with poor cardiac prognosis. In addition, a low bile acid synthesis predicted enhanced coronary mortality both in univariate and multivariate analysis, and in men bile acid synthesis was significantly correlated with cardiac mortality. Further analysis indicated that also in subjects without baseline myocardial infarction, low bile acid, cholesterol synthesis, or both predicted increased risk of coronary events. In multivariate analysis, male gender, previous myocardial infarction, and low bile acid synthesis at baseline explained 5%, 15%, and 5% (25%), respectively, of the variability of survival. Age, serum total cholesterol, and triglyceride values were unrelated to survival.