Novel haptoglobin insertion/deletion polymorphism is associated with the lipid profile and C-reactive protein (CRP)...

We discovered a hitherto undescribed insertion/deletion (I/D) polymorphism of 7 base pairs in intron 4 of the HP1 allele and intron 4 and 6 of the HP2 allele. Genotyping was performed in 311 Belgian subjects. The association between serum haptoglobin (Hp) and lipid concentrations and the Hp I/D genotypes was investigated. Genotype distribution in 103 Hp 1-1 phenotypes (50.5% DD, 39.8% DI, 9.7% II) and D allele frequency (0.70) were in close agreement with the Hardy-Weinberg equilibrium. No association between Hp concentrations and the Hp I/D genotypes could be found. Apolipoprotein (apo)A2, apoB and cholesterol concentrations were slightly lower in Hp II compared to DI and DD. Low-density lipoprotein (LDL)-cholesterol and ultrasensitive C-reactive protein (CRP) concentrations and the apoA1/apoA2 ratios differed significantly between Hp D/I genotypes. We added a further component to the molecular heterogeneity of Hp by the detection of an I/D polymorphism. Studies on the Hp I/D polymorphism in various populations open perspectives for further investigation of the distribution pattern of the human Hp gene. The association of the Hp I/D polymorphism with various lipid parameters might add a further component to the complex and multifaceted lipid metabolism.