INHERITANCE OF GLUCOSE TOLERANCE1

Abstract

The inheritance of glucose tolerance in rats was studied by crossing a Y strain rat family in which 71% of the [male][male] and 58% of the [female][female] gave diabetic-like glucose tolerances with a W strain family showing no evidence of low tolerance. The families employed were typical for the respective strains. Crossing the Y and W strains gave an F1 generation whose diabetic-like glucose tolerance was less than that of the Y stock in both incidence and severity. The sire appears to exert a greater influence than the dam on the type of glucose tolerance of the offspring. In the Fa generation from normal F1 animals the incidence of decreased tolerance in the [male][male] was only 14% and zero in the [female][female]. 4 individuals showed a glucose tolerance greater than that of the W strain. The appearance of these hyper-tolerant F2 animals suggests new combinations of hypo-glycemic genetic factors. The decreased glucose tolerance is not a simple recessive but is probably the result of one principal gene + modifiers, the principal gene tending to be incompletely recessive. The penetrance of this gene is less than 100% in homozygous combinations.