Unilateral split hand in one of monozygotic twins

Atypical split hand (left) was observed in one of monozygotic twins. The probability for monozygosity was 0.997 as based on 18 autosomal loci (11 blood groups and 7 enzymes and serum proteins). This observation supports the thesis that atypical split hand is not genetically determined and must be distinguished from autosomal dominant ectrodactyly.