Recessive inheritance of a relative fat pattern

We defined a relative-fat-pattern index (RFPI) as the ratio of subscapular skinfold thickness to the sum of subscapular and suprailiac skinfold thicknesses and computed RFPI for 774 adults (age greater than or equal to 25 years) in 59 pedigrees ascertained through cases of cardiovascular disease. Likelihood analysis of RFPI supported recessive inheritance of an allele with a frequency of 46%, which elevated mean RFPI from .412 to .533 when homozygous. The analysis apportioned the variance in RFPI as 42.3% due to the major locus, 9.5% due to polygenic inheritance, and 48.2% due to random environmental effects. Homozygotes for the recessive allele tended to have small suprailiac skinfold thicknesses rather than large subscapular skinfold thicknesses. Homozygotes were more frequent in younger than in older cases of obesity, coronary heart disease, essential hypertension, and diabetes mellitus; the increase was significant for all but diabetes.