Detection of the Pro664-Leu mutation in the low-density lipoprotein receptor and its relation to lipoprotein(a) levels in patients with familial hypercholesterolemia of Dutch ancestry from The Netherlands and Canada.

From a large cohort of hyperlipidemic patients, who attended the Lipid Research Clinic in Amsterdam, The Netherlands and in Vancouver, Canada, 915 consecutive patients with familial hypercholesterolemia (FH) of Dutch descent, were selected. This group of FH patients was screened for the presence of a cytosine to thymidine nucleotide substitution in exon 14 of the LDL-receptor gene, in order to determine the frequency of this mutation in patients of Dutch descent and to investigate the relationship between the mutation and the level of lipoprotein(a). The mutation was detected in seven individuals. All patients with this mutation shared the same haplotype, which is suggestive of an ancient mutation. The index patients and a large kindred with this mutation were further analyzed at the biochemical and clinical level. Except for total and LDL-cholesterol, there was no statistically significant difference in biochemical parameters between family members with and without FH. In contrast to previous reports, there was no difference in plasma levels of lipoprotein(a) between patients with the mutation in exon 14 and unaffected individuals.