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Title: Detection of a novel mutation Y468X in exon 10 of the low-density lipoprotein receptor gene causing heterozygous familial hypercholesterolemia among French Canadians

Familial hypercholesterolemia (FH) is caused by mutations in the low-density lipoprotein (LDL) receptor gene and characterized by raised plasma LDL-cholesterol (C) and premature coronary heart disease. FH has higher frequency among French Canadians (FC) in northeastern Quebec than in most other populations, 1:154 vs. 1:500. In FC, five mutations account for all the mutant alleles in homozygous FH and 81% in heterozygous FH; thus 19% are uncharacterized at the molecular level. We investigated the possibility of additional mutations(s), and direct sequencing of asymmetric PCR fragments showed a novel mutation (468 stop-codon) in the heterozygous form in exon 10 of the LDL receptor gene. This mutation results from cytosine to guanine transversion, converting codon 468 (TAC) encoding tyrosine into TAG stop-codon (Y468X). This nonsense mutation will result in a truncated protein shortened by 371 amino acids which will be rapidly degraded. However, we did not ascertain the functional aspects. We rather assessed its effects on the extent of elevation of LDL-C in heterozygous FH children. The Y468X mutation resulted in raised LDL-C levels which were comparable to subjects with a non-functional `null` allele due to deletion of the promoter region and exon 1 (237{plus_minus}49 vs. 248 {plus_minus}41 mg/dl; mean{plus_minus}SD, p<0.05). Themore » relative frequency of the Y468X mutation in a cohort of 343 children suspected for FH is 4.1% and it ranks number 4 in term of its prevalence. High frequency of FH among FC is attributed to a founder effect due to a high prevalence of one mutation; it is suggested that this novel mutation with low prevalence may be of later entry in this population.« less
Authors:
; ;  [1]
  1. Laval Univ., Quebec (Canada)
Publication Date:
OSTI Identifier:
134742
Report Number(s):
CONF-941009-
Journal ID: AJHGAG; ISSN 0002-9297; TRN: 95:005313-1480
Resource Type:
Journal Article
Resource Relation:
Journal Name: American Journal of Human Genetics; Journal Volume: 55; Journal Issue: Suppl.3; Conference: 44. annual meeting of the American Society of Human Genetics, Montreal (Canada), 18-22 Oct 1994; Other Information: PBD: Sep 1994
Country of Publication:
United States
Language:
English
Subject:
55 BIOLOGY AND MEDICINE, BASIC STUDIES; PATIENTS; METABOLIC DISEASES; HEREDITARY DISEASES; PHENOTYPE; CARDIOVASCULAR DISEASES; GENES; GENE MUTATIONS; DNA SEQUENCING; MUTATION FREQUENCY; DETECTION; RECEPTORS; LIPOPROTEINS; QUEBEC; EXONS; POLYMERASE CHAIN REACTION; CHOLESTEROL; CODONS; AMINO ACIDS; STATISTICS