Atypical segregation in the GPT group system. Determination of types and activity of enzyme in families.

Examination of GPT system in 5418 paternity cases confirmed the elimination of maternity in 21 cases. The study of 12 probant families displayed the occurrence of opposite homozygous types in parents and children. The result obtained showed the presence of GPT0 gene in the families examined. Similar results were obtained by examining five families of alleged fathers whose paternity was eliminated on the same basis. In 12 families the activity of GPT was determined. In majority of subjects with GPT0 gene, markedly lowered activity was observed. This also concerned several homozygous subjects who were identical with their parents. The lowered activity of the enzyme is not present in all subjects with a "silent gene", and therefore, its examination cannot be used for detection of the gene.