Genetic studies in a Hungarian isolate: Ivád.
A total of 675 individuals from the Hungarian isolate Ivád has been typed for 25 genetic polymorphisms. This sample was devided into three subgroups: 1. Full Ivádys (both spouses and their ancestors are members of the Ivád family; n = 330), 2. Half Ivádys (= either husband or wife and his or her, respectively, ancestors are from the Ivády family, the other partner from the outside population; n = 267), and 3. Non-Ivádys (married couples not belonging to the Ivády family; n = 78). The main concern of this paper is 1. to show to intra-Ivád variability of the distribution of various genetic parameters (allele frequencies, heterozygosity, gene diversity etc.) among these three groups, and 2. to analyze the impact of the different mating patterns of these groups on the genetic structure of the Ivád population. From the comparison of the Ivád gene frequencies with that of neighbouring populations (Pétervására and Erdökövesd) it is seen that drift or founder effects played some role. Within the Ivád population only few gene frequencies show a marked heterogeneity. As expected the average heterozygosity in Full Ivádys is somewhat lower than in Half Ivádys and Non-Ivádys, respectively. The pattern of genetic relationships of the various Ivád groups is in conformity with the demographic and historical facts of this village.