[Frequency of occurrence of apolipoprotein E isoforms in patients with various types of hyperlipoproteinemias]

Apolipoprotein E is a polymorphic protein playing a crucial role in the metabolism of plasma lipoproteins. Three alleles referred to as epsilon 2, epsilon 3 and epsilon 4 code for three common isoforms of apoE. The most frequent allele in the population at large is epsilon 3 allele. epsilon 2 and epsilon 4 alleles are connected with lipoprotein disorders as well as with other diseases. The aim of our study was to establish frequencies of apoE coding alleles in patients with different types of hyperlipidaemia (HLP) and to reveal differences in their distribution in comparison with the general population.

Therefore apoE genotype was assayed in 752 patients with primary HLP and 291 subjects randomly selected from the general Czech population. Allele frequencies were determined separately in a group of patients with familial hypercholesterolaemia (FH), polygenic hypercholesterolaemia (PHC), familial combined hyperlipidaemia (FCH) and in patients with type III. hyperlipidaemia (III). In patients with HLP a significantly higher frequency of epsilon 4 allele than in control subjects was found. In the group of FH patients frequency of the epsilon 2 allele was higher than in control subjects. In patients with PHC a significantly higher frequency of the epsilon 4 allele and lower frequency of the epsilon 2 allele were observed. In the group of FCH patients distribution of epsilon alleles did not differ from the control group. Frequency of the epsilon 2 allele in patients with type III. hyperlipidaemia was significantly higher than in controls.

We conclude that there exist significant differences in frequencies of apoE coding alleles between patients with primary hyperlipidaemia and a randomly selected population sample. The revealed differences in allelic distribution suggest that the impact of apoE polymorphism is not uniform in all types of hyperlipidaemia.