Population-based frequency of dyslipidemia syndromes in coronary-prone families in Utah.

The frequency of familial dyslipidemia syndromes was determined from blood tests in 33 objectively ascertained families with early coronary heart disease (CHD) (two or more siblings with CHD by the age of 55 years). Three fourths of persons with early CHD in these families had 90th percentile lipid abnormalities (cholesterol level at or above the 90th percentile, triglyceride level at or above the 90th percentile, and/or high-density lipoprotein cholesterol (HDL-C) level at or less than the 10th percentile). The HDL-C and triglyceride abnormalities were twice as common as low-density lipoprotein-cholesterol abnormalities. The most common syndromes found were familial combined hyperlipidemia (36% to 48% of families with CHD), familial dyslipidemic hypertension (21% to 54% of families with CHD), and isolated low levels of HDL-C (15%), with overlapping familial dyslipidemic hypertension with familial combined hyperlipidemia and low-level HDL-C. Well-defined monogenic syndromes were uncommon: familial hypercholesterolemia being 3% and familial type III hyperlipidemia, 3%. Another 15% of families with CHD had no lipid abnormalities at the 90th percentile. Physicians should learn to recognize and treat these common familial syndromes before the onset of CHD by evaluating family history and all three standard blood lipid determinations. Failure to recognize and treat them leaves affected family members at high risk of premature CHD.