Heritability and heteromorphic distributions of AluI chromosome banding variants in twins

The heritability and heteromorphic appearance of chromosomal banding patterns induced through in situ digestion with the restriction enzyme AluI were studied by analyzing the chromosomes of 25 monozygotic and 25 dizygotic twin pairs selected at random from a juvenile twin registry. A total of 19 AluI banding variants were found to be heteromorphic, with the pericentromeric region of chromosome 3 and the satellites of chromosome 22 being most and least heteromorphic, respectively. As expected, the correlations of the semi-quantitative scores for each of the chromosomal variants were significantly higher between MZ twin pairs (ranging from 0.48 to 0.95) than DZ twin pairs (ranging from -0.02 to 0.69), suggesting that genetic factors play an important role in their appearance. This finding was confirmed in a model fitting analysis in which the heritabilities of the AluI-induced chromosome variants were found to range from 70 to 96% for 12/13 heteromorphisms studied. These consistent findings are significant in that these variants may be useful for family studies in clinical genetics.