De erfelijkheid van de dizygote tweelingzwangerschap

The inheritance of dizygotic (DZ) twinning was investigated in 1422 pedigrees of DZ twin families and the phenotype modelled as a dichotomous trait with a female-specific expression. The observed frequencies of grandmothers with a DZ twin were compatible with autosomal but not with X-linked models. An autosomal monogenic dominant model with a gene frequency of 3.5% and a probability of expressing the trait of 10% for gene carriers revealed itself as the best fitting model. The same dominant model was observed for families of spontaneous DZ twins and DZ twins conceived after the administration of fertility-enhancing medication.