[The inheritance of hypodontia in families--the segregational analysis]

The aim of this study was to establish the mode of inheritance of hypodontia based on family data, and by means of segregational analysis to test whether this anomaly follows the expected ratio of segregation for the expected mode of inheritance. The research has been performed by analysing pedigrees of 35 families with hypodontia. Genealogical analyses suggest that hypodontia follows an autosomal dominant (AD) mode of inheritance in 21 families. The sample has been obtained by single incomplete ascertainment. The following methods have been applied for segregational analysis: Weinberger's proband method, Davie's method, Fisher's method, Robert's method, and finally Penrose's of a "relative frequency" method. Weinberger's method showed the value of 0.27 (27%) of the segregation of genes for hypodontia of the chosen sample and in case of Davie's method 0.28 (28.57%). Fisher's "sib" method gave the same results as Davie's method (28.57%). Roberts's formula showed that the value of X2 was 1.76, what means that there is no significant deviation from the expected 1:1 ratio. The results obtained are in favor of the autosomal dominant mode of inheritance. Penrose's method of a "relative frequency", suitable for differencing monogenic from polygenic inheritance, also showed autosomal dominant mode of inheritance of hypodontia in the analyzed sample.