Population structure of two black Venezuelan populations studied through their mating structure and other related variables.

In order to obtain information about the population structure of two black Venezuelan populations with historical differences both in their origins and development, a variety of variables were utilized, especially on marital structure, including: frequency of surnames, isonymy, population genealogical consanguinity, multiple unions, and marital distances, all of which provided information and isolation, migration, endogamy, consanguinity, and patri-matrifocality. Results showed differences in the extent of isolation and endogamy, as well as differences in population structure, which can be directly related with historical conditions of each population. Results agree with those previously obtained with traditional genetic polymorphisms and with the historical information available.

[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.

Enamel hypoplasia and age at weaning in 19th-century Florence, Italy.

A sample representing a population of the Florence district of middle 19th century was studied to determine the age of occurrence of enamel hypoplasias. The age interval most affected was that between 1.5 and 3.

Autosomal recessive ectodermal dysplasia: I. An undescribed dysplasia/malformation syndrome.

We describe 27 individuals of 7 families related to each other with high probability who showed manifestations of ectodermal dysplasia and other anomalies affecting females as severely as males with variable expressivity. All parents were normal. These families were detected in a relatively isolated and inbred population with very small neighbouring communities from a Caribbean Sea island, Margarita Island, in Northeastern Venezuela (Nueva Esparta State).

[Amelogenesis imperfecta. Description of a clinical case].

A family of five was examined. Four of them presented with enamel alteration including changes in colour and loss of enamel surface. A genetic study was undertaken which revealed an autosomal dominant inheritance with complete penetration and variable expressivity.