A MEDICAL GENETIC-STUDY OF THE POPULATION OF THE MARII EL REPUBLIC - GENETIC LOAD IN 4 DISTRICTS OF THE REPUBLIC

A medical genetic study of Orshanskii, Morkinskii, Sovetskii, and Semu rskii raions (districts) of the Marii El Republic was performed. The t otal number of subjects examined was 115743. Meadow Maris and Russians accounted for the most part of the populations of the districts studi ed. A total of 147 families with presumably autosomal dominant (AD) pa thology and 150 families with presumably autosomal recessive (AR) or X -linked pathology (270 and 169 affected persons, respectively) were re vealed. Segregation analysis demonstrated a good agreement between the observed and expected segregation frequencies for both AR and AD dise ases, as well as a considerable number of sporadic cases of presumably AD diseases. The incidence of hereditary diseases was estimated separ ately for different population groups. Significant differences in this incidence were revealed between the urban and rural, as well as betwe en the Russian and Mari populations; the average incidence was 2.33 af fected subjects per 1000 people. The incidence of AR diseases was sign ificantly higher in Maris than in Russians (1.34 x 10(-3) and 0.82 x 1 0(-3), respectively). The populations studied exhibited a significant, high correlation between the incidence of AR diseases and the levels of random and local inbreeding. The incidence of X-linked recessive di seases was approximately the same as in Russian populations studied ea rlier. Its average value was 0.5 per 1000 men; the incidence in the Ma ri and Russian populations did not differ significantly. The higher AD incidence in the total population studied and the higher AR incidence in the Meadow Mari population compared to the populations studied ear lier are discussed.