SOURCES OF VARIABILITY OF HUMAN PLASMA APOLIPOPROTEIN A-IV LEVELS ANDRELATIONSHIPS WITH LIPID-METABOLISM

Plasma apolipoprotein (ape) A-IV concentration was determined by immun oelectrophoretic assay (EIA) in 119 nuclear families. No significant e ffect of concomitants such as age, weight, height, body mass index, to bacco, and alcohol consumption was observed on apo A-IV levels in men and in boys. In women, contraceptive use and hormonal status affected ape A-IV levels. In girls, only age influenced the quantitative phenot ype. After adjusting by specific concomitants significant correlations were observed between ape A-IV levels and triglycerides, apolipoprote in A-I and ape B levels, suggesting a role of apolipoprotein A-IV in t he hepatic lipid metabolism. Intrafamilial correlations were estimated to investigate the plausibility of a common family factor. The result s obtained in this study showed a significant correlation between fami ly members with the exception of mother-daughter pairs. Using a varian ce components model, the contribution of genetic and environmental fac tors was then investigated. Different statistical models were used and two major hypotheses were statistically acceptable: the first hypothe sis supports that shared and specific environmental factors explain 35 and 65%, respectively, of the total adjusted plasma apo A-IV variatio n. The fraction of apo A-IV variability attributable to genetic factor s was null. The second hypothesis supports that the fraction of variab ility attributable to ape A-IV genetic variation is 67% and the common spouse environmental factors are responsible for 33% of the total var iability and no specific environmental effect was found. Among the two hypotheses, taking account of the metabolism function, we support the first one without excluding gene-environment interactions which could mask the genetic influence. (C) 1994 Wiley-Liss, Inc.