Detecting familial defective apolipoprotein B-100: three molecular scanning methods compared.

Familial defective apolipoprotein (apo) B-100 (FDB), a condition that may give rise to hypercholesterolemia, is caused by mutations around codon 3500 of the apo B gene. We have compared the ability of three molecular-scanning techniques, heteroduplex analysis, single-strand conformation polymorphism (SSCP) analysis, and denaturing gradient gel electrophoresis (DGGE), to detect these mutations in a cohort of 432 hypercholesterolemic individuals. Heteroduplex analysis and DGGE detected 11 individuals with apo B mutations, 9 of whom were heterozygous for apo B R3500Q and 2 who were heterozygous for apo B R3531C. Whereas DGGE was able to distinguish between these two mutations, heteroduplex analysis was technically simpler and gave a higher sample throughput. In contrast, SSCP analysis detected only 7 of the R3500Q and none of the R3531C heterozygotes and was the most complex of the three techniques. We believe heteroduplex analysis to be the method of choice for screening large numbers of samples for FDB.

Familial ligand-defective apolipoprotein B-100: detection, biochemical features and haplotype analysis of the R3531C mutation in the UK.

Familial ligand-defective apolipoprotein (apo) B-100 (FDB) is an autosomal codominant disorder which may give rise to hypercholesterolaemia. It is caused by the substitution of glutamine for arginine at codon 3500 of the apo B gene (apo B R3500Q), resulting in decreased binding of low density lipoprotein (LDL) to the LDL receptor. In order to search for other mutations in this region of the apo B gene, we have screened genomic DNA, obtained from 412 hypercholesterolaemic individuals, using heteroduplex analysis. Additional heteroduplex bands were observed following analysis of DNA from 11 individuals, nine of whom were heterozygous for apo B R3500Q. The two remaining individuals, both of Celtic origin, were shown by DNA sequencing to be heterozygous for a C-->T transition at nucleotide 10800 of the apo B gene, resulting in the substitution of cysteine for arginine at codon 3531 (apo B R3531C). Both had a strong family history of atherosclerosis and family studies revealed a further four individuals heterozygous for the mutation, three of whom were hypercholesterolaemic. Individuals heterozygous for apo B R3531C and R3500Q had mean +/- S.E.M. cholesterol concentrations of 7.82 +/- 0.68 and 8.53 +/- 0.31 mmol/l, respectively. These values were significantly higher than the value of 5.51 +/- 0.23 mmol/l observed in their unaffected relatives. These findings suggest that apo B R3531C is both less common in the UK and gives rise to a less severe form of hypercholesterolaemia than the classical 3500 mutation. In one of the families, the R3531C mutation occurred on a haplotype, compatible with that previously assigned to the mutation in a North American family also of Celtic origin. This is consistent with the mutation having been inherited from a common distant ancestor in individuals of Celtic origin.

Immunochemistry of the capsular polysaccharides from Clostridium perfringens: selected Hobbs strains 1, 5, 9, and 10.

The properties of the immunochemically distinct substances isolated from four strains of Clostridium perfringens, mucoid variants of Hobbs 1, 5, 9, and 10, were shown to be compatible with the hypothesis that polysaccharides are generally responsible for the "type-specificity" of these organisms. The presence of "group-specific" substance was demonstrated by the cross-reaction of recent preparations of Hobbs 5 antisera with the isolated polysaccharides. The cross-reactions were not observed with specific antisera of the other strains studied and were independent of the "type-specific" phenomenon.