Low-density lipoprotein receptor gene mutation analysis and clinical correlation in Belgian hypercholesterolaemics

It is generally believed that patients with familial hypercholesterolaemia (FH) have a higher cardiovascular risk than hypercholesterolaemics without a defect in the low-density lipoprotein receptor (LDLR) gene. However, no conclusive evidence to support this view has yet been presented. We investigated this aspect in Belgian hyperlipidaemics as part of a comprehensive effort to determine the impact of FH in this population. DNA samples of 98 unrelated Belgian patients with a family history of autosomal dominant hypercholesterolaemia were screened for mutations in the LDLR gene, after exclusion of known mutations causing familial defective apolipoprotein B-100 (FDB). Eight of the 22 distinct LDLR gene mutations identified in 27 subjects have not previously been described in other populations. As expected, the mutation-positive patients had a significantly worse lipid profile than the mutation-negative subjects (p<0.05), but this did not correlate with clinical cardiovascular status. In conclusion, the presence of a mutation in the LDLR gene was not a reliable predictor of cardiovascular risk in the hyperlipidaemic subjects included in this study. However, it is possible that prolonged exposure to the high levels of LDL cholesterol in genetically proven FH patients will in future cause a higher incidence of coronary heart disease. Our data may reflect the genetic heterogeneity of inherited hypercholesterolaemia, recently shown to be caused by several major genes.