Thyroid Dysgenesis in Two Pairs of Monozygotic Twins and in a Mother and Child

Abstract

Cretinism due to thyroid dysgenesis was observed in 2 sets of monozygotic twin girls. Identical zygosity was established by physical examination, determination of 6 blood group antigens and, in one pair, fingerprint analysis and haptoglobin typing. The diagnosis of cretinism was based originally on the clinical features, the response to thyroid medication and on ancillary investigations. One pair were considered to be athyreotic and the other pair had residual thyroid and ectopic tissue, respectively. Thyroid dysgenesis is not a common congenital disorder and only 1 in 250 births is of monozygotic twins. The occurrence of this condition in 2 pairs of monozygotic twins, of healthy mothers, and in another pair, a mother and daughter, may therefore indicate that one etiological factor is sometimes genetically determined, but further evidence is required to substantiate or refute this possibility.