Familial defective apolipoprotein B-100 in 12 subjects and their kindred

Twelve unrelated subjects with heterozygous familial defective apolipoprotein B-100 were identified in a group of 252 patients with type IIa hypercholesterolaemia. Approximately 5% of hypercholesterolaemia can be explained by this mutation in the collective studied. Familial defective apolipoprotein B-100 is therefore the most common known mutation causing primary hypercholesterolaemia. Family studies revealed an additional 14 affected subjects. All family members with the mutation had elevated cholesterol concentrations. In a normolipidaemic control group of 146 subjects the mutation was not present. In the affected individuals a variable expression of total cholesterol concentrations and atherosclerosis was observed. Plasma cholesterol ranged from 6.60 to 14.89 mmol/l with a mean of 9.43 mmol/l. Premature atherosclerosis was present in 4 patients, while one affected woman is now 92 years old and has no symptoms of coronary heart disease or peripheral atherosclerosis. Analysis of the haplotypes and genotypes by 3 biallelic and 1 multi-allelic DNA marker suggests that the disorder is caused in all affected patients by the same rare allele. The fact that the same mutant allele was also identified in other European populations and in a North American population of Caucasian origin argues for a common European origin of this mutation.