Influence of apolipoprotein H polymorphism on levels of triglycerides

Human apolipoprotein H (apo H) displays a genetically determined structural polymorphism: three alleles (H*1, H*2 and H*3) on chromosome 17 code for the six phenotypes (three homozygotes and three heterozygotes). The effect of apolipoprotein polymorphism on individual variations in plasma lipoprotein levels has been underscored in recent years. Since apo H is involved in metabolism of triglycerides (Tg), its phenotype could affect Tg levels. This paper reports an investigation of apo H phenotypes in a sample of 217 subjects of the Italian population by means of isoelectrofocussing followed by immunoblotting. The levels of the main lipid parameters were evaluated in relation to phenotype and other influential factors. Analysis of covariance disclosed a significant association between Tg levels (log transformed) and phenotype (F = 8.27, P = 0.004). Comparison of Tg levels between bearers of the two most frequent phenotypes (H2/2 and H3/2) divided by sex and age classes revealed significantly higher levels in male H3/2 heterozygotes (P = 0.0053) and in H3/2 subjects aged less than 50 (P = 0.0095). Our data support the view that there is an association between hypertriglyceridaemia and apo H polymorphism, especially with the H*3 allele.