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Presents a study which determined the origin and population distribution of G197del low-density lipoprotein receptor and its environmental and genetic effects on disease expression. Materials and methods; Results; Discussion.

Background and aims Familial hypercholesterolemia (FH) is an autosomal dominant disease caused by mutations in the genes for LDL receptor ( LDLR ), apolipoprotein B ( APOB ) and proprotein convertase subtilisin/kexin type9 ( PCSK9). The purpose of the current investigation was to define the current spectrum of mutations causing FH in Israel. Methods New families were collected through the MEDPED (Make Early Diagnosis Prevent Early Death) FH program. Molecular analysis of the LDLR , PCSK9 and APOB genes was done using High Resolution Melt and direct sequencing in 67 index cases. A 6-SNP LDL-C gene score calculation for polygenic hypercholesterolaemia was done using TaqMan genotyping. Results Mean serum cholesterol was 7.48 ± 1.89 mmol/L and the mean serum LDL-C was 5.99 ± 1.89 mmol/L. Mutations in the LDLR and APOB gene were found in 24 cases (35.8%), with 16 in LDLR, none in PCSK9 and one, p.(R3527Q), in the APOB gene, which is the first APOB mutation carrier identified in the Israeli population. Of the LDLR mutations, two were novel; p.(E140A) and a promoter variant, c.-191C > A. The c.2479G > A p.(V827I) in exon 17 of the LDLR gene was found in 8 patients (33.3% of the mutations) with modestly elevated LDL-C, but also in a compound heterozygous patient with a clinical homozygous FH phenotype, consistent with this being a “mild” FH-causing variant. A significantly higher 6-SNP LDL-C score was found in mutation-negative cases compared with a normal Caucasian cohort ( p = 0.03), confirming that polygenic inheritance of common LDL-C raising SNPs can produce an FH phenocopy. Conclusions The results indicate a different spectrum of genetic causes of FH from that found previously, in concordance with the heterogeneous and changing origins of the Israeli population, and confirm that a polygenic cause is also contributing to the FH phenotype in Israel. [ABSTRACT FROM AUTHOR]

Apolipoprotein E (apo E) is an essential constituent of several plasma lipoproteins, and plays an important role in lipoprotein metabolism. The apo E gene exhibits two common functional polymorphisms, producing 3 isoforms known to be associated with the risks of developing cardiovascular disease and susceptibility to Alzheimer's disease. Numerous different methods have been established for determining the three apo E isoforms, yet there are disadvantages and ambiguities associated with all of them. We used a method adapted for multiplex automated primer extension analysis by improving a commercially available protocol (SNaPshot) and simultaneously typing apo E single nucleotide polymorphisms (SNPs) encoding for isoforms at codon 112 and 158. This protocol relies on the extension with fluorescent dideoxyNTPs of a primer that ends one nucleotide 5' of a given SNP (minisequencing). Improvement of the method is achieved by incorporating into the minisequencing reaction two pooled primers corresponding to both apo E SNPs followed by analysis on an ABI PRISM 310 DNA sequencer. We found full concordance with genotypes determined using universal heteroduplex. This method is readily available for many laboratories and is a simple, unequivocal easy to use technique suitable for large amount of clinical samples that may provide a significant improvement over previously reported methods for apo E genotyping. [ABSTRACT FROM AUTHOR]

Compares cholesterol-lowering gene maps of familial hypercholesterolemia families with normal low density lipoprotein levels and homozygous individuals. Genetic variation in lipid concentration.