Genetico-mathematical analysis of the inheritance pattern of ulcer disease. A posteriori methods. The maximum likelihood method.

Inheritance pattern of ulcer disease was analysed genetico-mathematically using one of the a posteriori methods--the method of maximum likelihood. We studied the families of 351 hereditary predisposed probands of whom 57 with type II gastric ulcer disease, 27 with type III gastric ulcer disease and 267 with duodenal ulcer disease. The types of ulcer disease were determined according to H. Johnson. The analysis of the patients with duodenal ulcer also included the types of familial predisposition of the probands. The results yielded by the maximum likelihood method excluded to a great degree the possibility of monogenic transmission of ulcer disease. None to the three types of peptic ulcer showed autosomal recessive pattern of inheritance; it was not found even in the families with phenotypically healthy but hereditary predisposed parents. No evidence was found of autosomal dominant pattern of inheritance of the disease in all studied groups including the families with one sick parent. This is supported by the different values of the segregation coefficients in the families with one sick father and one sick mother. The absence of evidence for monogenic mode of inheritance of the disease indicated by the detailed genetico-mathematical analysis should be further evaluated by the criteria of polygenicity.