Autosomal genetic control of the activity of a new variant ornithine transcarbamylase in chicken kidney.

The mode of inheritance of the gene for chick kidney ornithine transcarbamylase (OTC), found previously as a genetic variant, was investigated. White Leghorn B line males homozygous for the allele for the variant OTC gene were selected using the California Gray breed, having a near-absolute deficiency of the enzyme. Then further crosses of the two breeds were made. The mean value of the OTC level of F1 progeny was about 170 units. Chicks from the backcross generation were divided into two groups, of high activity and low activity, in a ratio of 1:1. F2 chicks were divided into three groups: one-fourth of the chicks were classified as a "super high" group, one-half were "high," and the remaining one-fourth were "low"; the mean values for OTC level were 356.7, 196.4, and 15.6 units, respectively. From these results, it was suggested that the variant OTC represents a simple autosomal incompletely dominant trait.