Novel and recurrent LDLR gene mutations in Pakistani hypercholesterolemia patients

• Published in: Molecular biology reports 2012-07, Vol.39 (7), p.7365-7372
• Main Authors: Ahmed, Waqas, Ajmal, Muhammad, Sadeque, Ahmed, Whittall, Roslyn A., Rafiq, Sobia, Putt, Wendy, Khawaja, Athar, Imtiaz, Fauzia, Ahmed, Nuzhat, Azam, Maleeha, Humphries, Steve E., Qamar, Raheel
• Format: Article
• Language: English
• Subjects: Adult; Amino Acid Sequence; Amino acid substitution; Animal Anatomy; Animal Biochemistry; Biomedical and Life Sciences; Cholesterol; Exons; Female; Genetic disorders; Hereditary diseases; Histology; Humans; Hypercholesterolemia; Hyperlipoproteinemia Type II - diagnosis; Hyperlipoproteinemia Type II - genetics; LDLR gene; Life Sciences; Lipoprotein (low density) receptors; Low density lipoprotein receptors; Male; Melting; Middle Aged; Molecular Sequence Data; Morphology; Mutation; Nucleotides; Pakistan; Pedigree; Polymerase chain reaction; Polymorphism; Protein structure; Protein Structure, Secondary; Receptors, LDL - chemistry; Receptors, LDL - genetics; Restriction fragment length polymorphism; Young Adult
• ISSN: 0301-4851; 1573-4978
• DOI: 10.1007/s11033-012-1568-1

The majority of patients with the autosomal dominant disorder familial hypercholesterolemia (FH) carry novel mutations in the low density lipoprotein receptor ( LDLR ) that is involved in cholesterol regulation. In different populations the spectrum of mutations identified is quite different and to date there have been only a few reports of the spectrum of mutations in FH patients from Pakistan. In order to identify the causative LDLR variants the gene was sequenced in a Pakistani FH family, while high resolution melting analysis followed by sequencing was performed in a panel of 27 unrelated sporadic hypercholesterolemia patients. In the family a novel missense variant (c.1916T > G, p.(V639G)) in exon 13 of LDLR was identified in the proband. The segregation of the identified nucleotide change in the family and carrier status screening in a group of 100 healthy subjects was done using restriction fragment length polymorphism analysis. All affected members of the FH family carried the variant and none of the non-affected members nor any of the healthy subjects. In one of the sporadic cases, two sequence changes were detected in exon 9, one of these was a recurrent missense variant (c.1211C > T; p.T404I), while the other was a novel substitution mutation (c.1214 A > C; N405T). In order to define the allelic status of this double heterozygous individual, PCR amplified fragments were cloned and sequenced, which identified that both changes occurred on the same allele. In silico tools (PolyPhen and SIFT) were used to predict the effect of the variants on the protein structure, which predicted both of these variants to have deleterious effect. These findings support the view that there will be a novel spectrum of mutations causing FH in patients with hypercholesterolaemia from Pakistan.