[Analysis of consanguinity in some populations of the V Region, Valparaiso, Chile, from 1880 to 1969].

The population structure of 10 populations ("comunas") in Valparaíso, V Region Chile, was studied through the frequency of consanguineous marriages (%CM) and the coefficient of consanguinity (alpha), in order to know their dynamics, and gather information for clinical and genetic epidemiological studies as well as for isonymy studies. The comunas were grouped according to density: Group I, high density, more than 100 inhabitants/km2; Group II, intermediate, between 25 and 99 inhabitants/km2; and Group III, low, less than 25 inhabitants/km2. Data were obtained from parochial archives and national census, from 1880 to 1969. CM's were divided in: uncle-aunt/nephew-niece (12), first cousins (22), first cousins one removed (23), second cousins (33) and multiple consanguinity (M), and the four subtypes of 12 and 22. Percentage of CM and alpha diminish in time. Groups I and II show similar values, but lower in I, and show a constant decrease. Group III has higher values and considerable fluactuations. Types 12 and 22 contribute mostly to %CM and alpha in the 3 groups. Subtypes of 12 and 22 do not occur at random. This temporary and spatial behavior can be explained because of sociocultural and socioeconomical factors in each group, being density an indicator of endogamy. This behavior is consistent with current coefficients of endogamy obtained by isonymy.