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Characterization of a disease‐causing Glu 119 ‐Lys mutation in the low‐density lipoprotein receptor gene in two Danish families with heterozygous familial hypercholesterolemia
Author(s) -
Jensen Henrik K.,
Jensen Thomas G.,
Jensen Lillian G.,
Hansen Peter S.,
Kjeldsen Margrethe,
Andresen Brage S.,
Nielsen Viggo,
Meinertz Hans,
Hansen Annebirthe B.,
Bolund Lars,
Færgeman Ole,
Gregersen Niels
Publication year - 1994
Publication title -
human mutation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 162
eISSN - 1098-1004
pISSN - 1059-7794
DOI - 10.1002/humu.1380040203
Subject(s) - familial hypercholesterolemia , biology , point mutation , haplotype , ldl receptor , mutation , microbiology and biotechnology , compound heterozygosity , genetics , exon , mutant , allele , gene , lipoprotein , biochemistry , cholesterol
Mutations in the gene for the low‐density lipoprotein receptor (LDL receptor) cause the autosomal dominant inherited disease familial hypercholesterolemia (FH). In 15 Danish patients with heterozygous FH we have screened exon 4 of the LDL receptor gene for point mutations and small rearrangements employing genomic DNA amplification and bidirectional solid‐phase sequencing. Two subjects were found to be heterozygous for a guanine to adenine base substitution at nucleotide position 418 of the LDL receptor cDNA. This point mutation results in an amino acid change from glutamic acid to lysine at amino acid residue 119 in the third repeat of the cysteine‐rich ligand binding domain of the mature LDL receptor. Disruption of LDL receptor function by the Glu 119 ‐Lys mutation was confirmed by site‐directed rnutagenesis and expression in COS‐7 cells. By Western blotting the mutation was found to affect the processing of the LDL receptor protein. Using flow cytometric analysis of the transfected cells a decreased binding and internalization of LDL by the mutant receptor was documented. By means of a mutation‐specific PCR‐based assay the Glu 119 ‐Lys mutation was not detected in another 85 apparently unrelated Danish heterozygous FH patients. We identified six persons in the index families with the Glu 119 ‐Lys mutation cosegregating with the clinical syndrome of FH in these families. Furthermore, haplotype analysis revealed that the haplotype [S fa NI+, S tu I+, A va II–, (dTA) 7 ] of the mutation carrying allele was the same in the two apparently unrelated patients. This indicates that the mutation has been inherited from a common ancestor. © 1994 Wiley‐Liss, Inc.