Associations of the ABO blood groups with cardiovascular disease and serum lipid levels have been established, but the exact relation to lipoproteins and atherosclerosis remains to be determined.
We still need to know which tissues take up the most LDL; we need to know how much LDL is cleared by the liver and whether this clearance involves the same LDL receptor that operates in extra-hepatic cells; we need to know the mechanism for the clearance of the one-half to two-thirds of LDL that leaves the plasma by receptor-independent pathways; and finally we need to know how an abnormal accumulation of LDL in the plasma leads to the deposition of cholesterol in scavenger cells and produces atherosclerosis.
We have recently isolated and characterized the human apo A-I gene and have shown that apo A-I and apolipoprotein C-III (apo C-III) genes are physically linked and that a polymorphism (of unknown frequency in the general population) of the apo A-I gene is inherited as a mendelian trait linked to premature atherosclerosis in an affected family (not the same polymorphism as has previously been reported to be associated with hypertriglyceridaemia).
In addition to the three major isoforms of apolipoprotein E (apo E-4, E-3, and E-2) and the new one (apo E-5) which was recently found in this laboratory, we have discovered an additional series of components, which showed themselves as at least three bands on an isoelectric focusing gel in the region of E-VII through E-V, in four patients with hyperlipidemia and atherosclerosis.
Patients affected by mixed hyperlipidemia should be investigated for their apolipoprotein E polymorphism because of the possible linkage of apolipoprotein E2/2 homozygosity, hyperlipidemia, and atherosclerosis.
A six-year-old girl with severe hypercholesterolemia and atherosclerosis had two defective genes at the low-density-lipoprotein (LDL) receptor locus, as determined by biochemical studies of cultured fibroblasts.
We have recently reported that the human apolipoprotein A-I (apoA-I) and apolipoprotein C-III (apoC-III) genes are physically linked and that the presence of a DNA insertion in the apoA-I gene is correlated with apoA-I-apoC-III deficiency in patients with premature atherosclerosis.
We have recently reported that the human apolipoprotein A-I (apoA-I) and apolipoprotein C-III (apoC-III) genes are physically linked and that the presence of a DNA insertion in the apoA-I gene is correlated with apoA-I-apoC-III deficiency in patients with premature atherosclerosis.
A genetic analysis of atherosclerotic patients as well as healthy subjects using an apoA-I gene specific probe confirmed that an EcoRI restriction fragment length polymorphism is related to the development of atherosclerosis.