Comparison of the genetic defect with LDL-receptor activity in cultured cells from patients with a clinical diagnosis of heterozygous familial hypercholesterolemia. The Familial Hypercholesterolaemia Regression Study Group.
In this study we have analyzed the genetic defect in 42 patients with a diagnosis of heterozygous familial hypercholesterolemia (FH) by Southern blotting, SSCP, and sequencing of PCR-amplified fragments of genomic DNA or sequencing of RT-PCR products from mRNA in cultured cells. The apoB Arg3500Gln mutation was identified in five patients. A molecular defect in the LDL-receptor gene was confirmed in 23 patients; 16 of these mutations have not been described before. No defect in the coding region, intron:exon junctions or proximal promoter of the LDL-receptor gene or in the region of the apoB gene coding for the LDL-receptor binding domain was found in the remaining 14 patients. LDL-receptor activity and protein content of cultured lymphoblasts from the patients was significantly lower in cells from patients with severe rather than mild LDL-receptor mutations. Cells from four patients with no detectable defect showed reduced LDL receptor activity compared with eight normal cell lines, whereas six others had reduced LDL-receptor activity but LDL-receptor protein content within the normal range. Cells from four patients appeared to have normal LDL-receptor function. Cells from two patients with a defined defect also had LDL-receptor activity within the normal range. The findings demonstrate the problems involved in the genetic diagnosis of FH in patients.
Sun
X M
XM
Lipoprotein Team, Hammersmith Hospital, London, UK.
Patel
D D
DD
Knight
B L
BL
Soutar
A K
AK
D000328:Adult; D001055:Apolipoproteins B / Q000235:genetics; D002478:Cells, Cultured; D002888:Chromosomes, Human, Pair 19 / Q000235:genetics; D004252:DNA Mutational Analysis; D015252:Deoxyribonucleases, Type II Site-Specific; D005260:Female; D018740:Genetic Heterogeneity; D006579:Heterozygote; D006801:Humans; D006938:Hyperlipoproteinemia Type II / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D015810:Linkage Disequilibrium; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008214:Lymphocytes / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D018807:Polymorphism, Single-Stranded Conformational; D012333:RNA, Messenger / Q000235:genetics; D011973:Receptors, LDL / Q000172:deficiency* / Q000235:genetics; D017384:Sequence Deletion
D001055:Apolipoproteins B; D008077:Lipoproteins, LDL; D012333:RNA, Messenger; D011973:Receptors, LDL; D015252:Deoxyribonucleases, Type II Site-Specific; C038308:GGWCC-specific type II deoxyribonucleases