CHARACTERISTICS OF 46 HETEROZYGOUS CARRIERS AND 57 UNAFFECTED RELATIVES IN 5 DANISH FAMILIES WITH FAMILIAL DEFECTIVE APOLIPOPROTEIN B-100

Plasma concentrations of cholesterol, high-density lipoprotein (HDL) c holesterol, low-density lipoprotein (LDL) cholesterol, apolipoprotein (apo) B, and lipoprotein(a) (Lp[a]) in 46 persons heterozygous for the apo B-3500 mutation causing familial defective apo B-100 (FDB) were c ompared with those in 57 non-FDB relatives. FDB patients had 50% to 70 % higher mean concentrations of cholesterol, LDL cholesterol, and apo B than non-FDB relatives (P<10(-4) for all three variables). Triglycer ides were higher (P=.016) and HDL cholesterol was lower (P=.021) in FD B patients. The concentration ranges of these variables were broad in each family, and there was no between-family difference in means for c holesterol and LDL cholesterol. There was no phenotype-specific differ ence in Lp(a) concentrations between FDB patients and non-FDB relative s. Apo E4 is normally associated with higher concentrations of LDL and apo E2 with lower concentrations. This relation was partly reversed i n FDB patients: apo E4 was associated with lower apo B concentrations and apo E2 with higher apo B concentrations. Tendon xanthomata were fo und in members of two of the five families. Six of 12 FDB patients >50 years old had atherosclerotic disease. In contrast, all 18 non-FDB re latives >50 years old were apparently healthy. A total of 8 FDB patien ts with atherosclerotic disease had 35% higher cholesterol concentrati ons, 28% higher apo B concentrations, 50% higher triglyceride concentr ations, and 120% higher Lp(a) concentrations than FDB patients without clinical atherosclerosis. The haplotype background for the apo B-3500 mutation in these Danish families, as defined with seven markers, was comparable to that found in kindreds from the United States, Canada, Austria, Italy, and Germany.