No evidence for chromosomal mosaicism in multiple tissues of 10 patients with 45 XO Turner syndrome

Abstract

Why the frequency of spontaneous abortions among monosomy X conceptuses is 98% while the postnatal course of Turner syndrome is relatively benign is not understood. Mosaicism for a euploid cell line could confer viability, and those 2% of 45,XO zygotes surviving in utero might have some degree of mosaicism. If the non-mosaic 45,XO karyotype is lethal, a thorough study of living Turner syndrome patients might reveal a much higher frequency of mosaicism than the 30-40% reported. Ten adult women with a 45,XO leukocyte karyotype were investigated, looking at 5 tissue types from all 3 germ layers: buccal mucosa and hair from ectoderm, urinary epithelium from endoderm and ectoderm, and lymphocytes and skin fibroblasts from mesoderm. Mosaicism in these patients was not confirmed, although in 2 out of 10 there was the suggestion of a small percentage of euploid cells in skin and blood karyotypes.