Genetical studies of the palmar and sole patterns and some dermatoglyphic measurements in twins.

The within- and between-pair mean squares and means have been estimated for dermatoglyphic patterns on finger-tips, palms and soles and compared between samples of 110 MZ and 111 DZ twins of Polish origin. Dermatoglyphic patterns have been represented by topologically significant pattern elements (loops and triradii) on finger-tips, palms and soles, considered separately and in various combinations, ridge counts on finger-tips and on palms and several other palmar and sole measurements. Some genetic parameters such as: genetic variance (GCT) based on within and between mean squares of the two types of twins, the within-pair variance ratio and the covariance/variance ratio in MZ twins have also been obtained for all these traits and considered in relation to differences in respect of the total and between-pair variances and means for all specified characters. The highest values of genetic parameters have been obtained for pattern intensities and ridge counts on finger-tips, considered separately or combined, for the H hypothenar loop and the axial t triradii on palms, and for the majority of sole loops and triradii. The lowest values have been found for several palmar loops and measurements such as minutiae counts. These results are, in respect of some pattern elements, not in agreement with the estimated heritability based on correlations between other relatives. A comparison of genetic parameters for single loops or triradii and for their various combinations indicates that some pattern elements or their combinations may be each influenced by a specific genetic system which modifies their phenotypic expression. It is believed that the obtained results are, for some proportion of characters, clearly biased by inequality of the total variances in MZ and DZ twins.