Prevalence of familial hypertriglyceridemia: The Princeton School District Family Study

Abstract Using the Princeton School Family Study cohort, our specific aim was to estimate the prevalence of suspected familial hypertriglyceridemia (FHTG), to study the potential contributions of secondary hypertriglyceridemias in hypertriglyceridemic probands, and to provide empirical risk estimates for the proportion of probands' first-degree relatives who also had top decile triglyceride levels. Suspected FHTG was arbitrarily identified in those kindreds having at least two first-degree relatives in the top age-sex-race-specific triglyceride decile, along with the proband. We studied 177 (125 white, 52 black) randomly recalled and 202 hyperlipidemic (hypertriglyceridemic and/or hypercholesterolemic) recall (147 white, 55 black) probands and their families. None of the 9 top triglyceride decile probands from the random recall group had FHTG. Of the 81 top triglyceride decile probands from the hyperlipidemic recall group, 23 (28%) had suspected FHTG, and 6 (7%) of the top triglyceride decile probands had suspected FHTG with three-generation vertical (and horizontal) transmission of top decile triglyceride. An average of 24% of the first-degree relatives of all hypertriglyceridemic probands themselves had top decile triglycerides. In hypertriglyceridemic probands and their affected relatives, factors that may cause secondary hypertriglyceridemia or exacerbate preexisting hypertriglyceridemia were common: poorly controlled diabetes mellitus, excessive alcohol intake, hepatic dysfunction, use of estrogen-progestin oral contraceptives, and use of antihypertensive agents. Quetelet index and alcohol intake had significant simple correlations with triglyceride levels; after adjusting for Quetelet index, alcohol had no significant independent relationship to triglycerides. There were significant partial correlations of triglycerides with systolic blood pressure and an inverse association of high-density lipoprotein cholesterol (HDLC) with diastolic blood pressure. In 14 of the 23 kindreds with suspected FHTG there were also 2 or more kindred members who had top decile low-density lipoprotein cholesterol (LDLC), suggestive of combined hyperlipidemia. Whatever definition of FHTG is used, identification of hypertriglyceridemia may reveal other underlying risk factors for coronary heart disease, including low HDLC, and/or elevated LDLC. The clustering of atherosclerosis in suspected FHTG kindreds may be related in part to familial clustering of high triglycerides, high LDLC, and/or low levels of HDLC.