Molecular genetic testing for familial hypercholesterolemia: spectrum of LDL receptor gene mutations in the Netherlands

Mutations in the LDL receptor are responsible for familial hypercholesterol emia (FH). At present, more than 600 mutations of the LDL receptor gene are known to underlie FH. However, the array of mutations varies considerably in different populations. Therefore, the delineation of essentially all LDL receptor gene mutations in a population represents a prerequisite for the implementation of nation-wide genetic testing for FH. In this study, the fr equency and geographical distribution of 13 known mutations were evaluated in a cohort of 1223 FH patients. We identified 358 mutation carriers, repre senting 29% of the FH cohort. Four mutations (N543H-2393de19, 1359 - 1 G -- > A, 313 + 1 G --> A and W23X) occurred with a relatively high frequency, a ccounting for 22.4% of the entire study cohort. Two of these common FH muta tions (N543H-2393de19 and 1359 - 1 G --> A) showed a preferential geographi c distribution. Second, to further expand the array of LDL receptor gene mu tations, we conducted mutation analysis by denaturing gradient gel electrop horesis (DGGE) in 141 children with definite FH. A mutation was identified in 111 patients, involving 16 new single base substitutions and four small deletions and insertions, which brings the number of different FH-causing m utations in our country up to 61. Our data indicate that an estimate of the prevalence of specific mutations, as well as the compilation of a database of all FH-causing mutations in a given country, can facilitate selection o f the most appropriate molecular diagnostic approach.