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An integrated medical genetic an population genetic study has been performed in two raions (administrative districts) of the Tver oblast (region) of Russia: the Udomlya raion located in the zone affected by the Kalininskaya Nuclear Power Plant and the Ostashkov raion, which served as a control district. No significant differences has been found with respect to the genetic parameters studied. The values of these parameters in the populations of the town of Udomlya, the town of Ostashkov, the Udomlya raion, and the Ostashkov raion, respectively, are the following: random inbreeding, 0.00006, 0.00011, 0.000167, and 0.000366; endogamy index, 0.05, 0.43, 0.30, and 0.42; local inbreeding, 0.0003, 0.00045, 0.0009, and 0.0011; the degree of isolation by distance, 0.0003, 0.00045, 0.0009, and 0.0005; sigma, 2098, 1338, 1473, and 1189; the load of autosomal dominant (AD) diseases, 0.71, 0.92, 0.92, and 1.37; the load of autosomal recessive (AR) diseases, 0.68, 0.69, 0.67, and 0.82; and the load of X-linked diseases, 0.18, 0.64, 0.83, and 0.27.

Comprehensive population genetic and medical genetic studies were performed in three raions (districts) of Chuvashia. The population of these districts is more than 90% Chuvash. About 70% of the families that completed reproduction had two or three children. The proportion of families with four or more children was 18%. The duration of generation was 27.6 years. The differential fertility and differential mortality indices in the Chuvash population were estimated at 0.33 and 0.076, respectively. The total index of differential selection was 0.403, which is typical of modern urbanized populations. Mean values of local inbreeding calculated from Malecot's model of isolation by distance were 0.00124 and 0.00377 for the urban and rural populations, respectively, of the districts studied. The prevalence rates of autosomal dominant (AD), autosomal recessive (AR), and X-linked diseases were found to be 0.47, 0.52, and 0.35 per 1000, respectively, in the urban population and 1.62, 1.14, and 0.31 per 1000, respectively, in the rural population. Significant correlation between the local inbreeding and prevalence rates of AD and AR diseases was found. A total of 43 AD and 43 AR diseases were identified. Some of them were not found in previous studies on other populations.

A summary of the medical genetic studies of the Marii El population is presented. A total of 276,900 people, 110,894 and 166,006 urban and rural inhabitants, respectively, were examined. Regarding the ethnic composition, the studied population was mostly Mari (61.96%) and Russian (32.04%). Medical genetic examination revealed 480 subjects from 260 families with autosomal dominant (AD) diseases, 234 subjects from 184 families with autosomal recessive (AR) diseases, and 49 subjects from 41 families with x-linked diseases. Segregation analysis revealed a good agreement between the expected and observed segregation frequencies for families with AR and AD diseases and allowed the frequency of hereditary diseases in the urban and rural, as well as the Russian and Mari, populations, to be estimated. The total frequency of AD diseases in Maris was approximately twice as high as in Russians (1.99 and 0.97%, respectively); substantial differences between district populations were found. The total frequency of AR diseases was also two times higher in Maris than in Russians (1.00 and 0.54%, respectively). The frequencies of AR and AD diseases in different districts were correlated with the levels of random and local inbreeding, population size, and the index of maximum selection.

The spectrum and prevalence rate of hereditary pathology in Kanevskii and Bryukhovetskii raions (districts) of Krasnodar krai (territory) were analyzed. The total size of the studied population was 145,937. The prevalence rate of monogenic hereditary pathology was estimated. This value was 1.08 +/- 0.08, 0.72 +/- 0.07, and 0.20 +/- 0.06 per 1000 people for autosomal dominant (AD), autosomal recessive (AR), and X-linked (XL) recessive diseases, respectively. Forty-two AD (158 affected persons in 82 families), 32 AR (105 affected persons in 82 families), and 6 XL disease entities (13 affected persons in 8 families) were found. A slight genetic subdivision was found in the populations of Kanevskii and Bryukhovetskii raions. However, it was not found to affect the prevalence of hereditary pathology.

The diversity of Mendelian hereditary pathology was studied in Marii El Republic. In total, 276,900 subjects, including 171,151 Maris and 88,714 Russians, living in seven raions (districts) were studied. Fifty-five autosomal dominant disease entities were found, with more than ten diseases having a frequency of 1:50,000 people or higher. In Maris, autosomal recessive hypotrichosis was observed at a relatively high frequency (1:15,337); this disease was not revealed in the Russian population studied earlier. Conversely, no phenylketonuria (PKU) was found in Maris, while it was a relatively common autosomal recessive disease in Russians. Regarding autosomal dominant pathology, 76 disease entities were revealed, with 21 diseases being observed at a frequency of at least 1:50,000. Ten X-linked diseases were found. The numbers of both autosomal recessive and autosomal dominant diseases exhibited a linear relationship with the number of subjects examined. The genetic structure of the Mari population was studied on the basis of data on the genes of recessive diseases. A matrix of Nei's genetic distances was calculated from the frequencies of 45 recessive diseases found in the seven districts studied. The average genetic distance calculated for the 45 loci of autosomal recessive diseases was 0.006175 x 10(-3). Similarly, matrix of genetic distances for five Mari populations was obtained (Medvedevskii and Zvenigovskii raions were not included) based on a total of 32 allelic frequencies for ten polymorphic immune and biochemical loci. The average genetic distance calculated from the ten polymorphic loci was 0.001930, i.e., 2.5 orders of magnitude greater than the average genetic distance for recessive diseases. The matrices of genetic distances for the five Mari populations calculated from the gene frequencies for recessive diseases and for the ten polymorphic systems were largely similar to each other. Thus, the main elements of the genetic structure of the Mari population can be estimated on the basis of gene frequencies for hereditary diseases. In this case, the characteristics of individual populations, which are more or less isolated, and of their interaction are the same as in the case of studying genetic structure with the use of polymorphic biological markers.

A medical genetic study of Orshanskii, Morkinskii, Sovetskii, and Semurskii raions (districts) of the Marii El Republic was performed. The total number of subjects examined was 115,743. Meadow Maris and Russians accounted for the most part of the populations of the districts studied. A total of 147 families with presumably autosomal dominant (AD) pathology and 150 families with presumably autosomal recessive (AR) or X-linked pathology (270 and 169 affected persons, respectively) were revealed. Segregation analysis demonstrated a good agreement between the observed and expected segregation frequencies for both AR and AD diseases, as well as a considerable number of sporadic cases of presumably AD diseases. The incidence of hereditary diseases was estimated separately for different population groups. Significant differences in this incidence were revealed between the urban and rural, as well as between the Russian and Mari populations; the average incidence was 2.33 affected subjects per 1000 people. The incidence of AR diseases was significantly higher in Maris than in Russians (1.34 x 10(-3) and 0.82 x 10(-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 diseases was approximately the same as in Russian populations studied earlier. Its average value was 0.5 per 1000 men; the incidence in the Mari 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 earlier are discussed.

A population and medical genetic investigation was performed in a number of raions in the Arkhangel' skaya oblast. Random inbreeding coefficients were 0.000358 and 0.000361 in the Vinogradovskii and Krasnoborskii raions. Malecot's local inbreeding coefficients were 0.000565 and 0.000472, respectively. The endogamy indices were 0.37 and 0.54, respectively. In the urban population, the loads of autosomal dominant, autosomal recessive, and X-linked pathology were 1.01 and 0.98 per 1000 individuals, and 0.29 per 1000 men; in the rural population, they were 1.22, 1.55, and 1.08, respectively. In the populations studied, the hereditary pathology spectrum is described.

The population of Gornomariiskii raion, Marii El Republic, primarily made up of mountain Marii, was subjected to medical genetic examination. The size of the entire population is 54853. Estimates of hereditary pathology in urban and rural populations of the raion were obtained. They were 0.68 and 1.11, respectively, for autosomal dominant pathology (AD); 0.55 and 0.81 for autosomal recessive pathology (AR); and 0.45 and 0.20 for X-linked pathology. Twenty-two, 25, and six nosologic forms of autosomal dominant, autosomal recessive, and X-linked diseases were revealed, respectively. We attempted to compare the sample under consideration with previously studied Russian and Finnish populations for rare pathologic recessive genes.

The main purpose of this report is to present the nosological spectrum of hereditary diseases in 9 Districts of Kirov Province and to compare it with that studies earlier in other Russian populations. This comparison is undertaken in an attempt to define a "nucleus" of hereditary diseases in the Russian population studied. During this study 343 families with 546 affected were registered. The spectrum covered 55 different autosomal dominant, 14 autosomal recessive and 11 X-linked recessive hereditary disorders in the population under study. Some of these forms could be considered as common forms for the whole Russian population, because they were met in all Russian populations which were analysed. This conclusion is proved by the cluster analysis of genetic distances calculated on the basis of gene frequencies for autosomal recessive hereditary disorders.

Medical-genetic study was carried out in the population of Kirov Province (population size about 120.000). 203 families with 334 affected with hereditary disorders were registered. The correctness of pathology classification for the inheritance type was confirmed by segregational analysis. The load of hereditary diseases in the population was: 1.25 +/- 0.06 for autosomal dominant, 1.37 +/- 0.07 for autosomal recessive and 0.22 +/- 0.06 for X-linked recessive disorders. It is suggested that variability in the values of the load of autosomal recessive disorders is determined to the large extent by genetic structure of the population.

Data on the prevalence of hereditary diseases in five regions of the Kostroma province were obtained and analysed. 28 autosomal recessive, 25 autosomal dominant and 4 X-linked recessive disorders were found. Segregation analysis proved the rightness of the material subdivision, according to the type of inheritance. The load of hereditary diseases in five regions was: 0.86 +/- 0.09 X 10(3) for autosomal recessive, 0.97 +/- 0.1 X 10(3) for autosomal dominant and 0.36 +/- 0.09 X 10(3) for X-linked recessive disorders. The problems of prevalence of hereditary diseases connected with population structure is discussed.

The diversity of hereditary pathology in Kostroma was studied. An attempt was made to classify all isolated cases by genetic and clinical analysis. 57 nosological forms of autosomal dominants, 41 autosomal recessive and 14 X-linked recessive disorders were found. The analysis of marriage distances in the whole population and in the families of the probands was carried out. The spectra of hereditary pathology in Kostroma and Kostroma Province were compared. The sources of the load of hereditary pathology in Kostroma are discussed.