Monozygotic twins discordant for Ullrich-Turner syndrome

P. B. Kaplowitz, J. Bodurtha, J. Brown, J. E. Spence

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


We describe 9-year-old twin girls who were thought to be monozygotic but who differed greatly in physical appearance and growth pattern. One twin had Ullrich-Turner syndrome (UTS),45,X/46,XX mosaicism in peripheral blood, and only 45,X cells in skin fibroblasts. The phenotypically normal twin also had 45,X/46,XX mosaicism in blood but only 46,XX cells in cultured fibroblasts. Analysis of DNA marker patterns in blood lymphocytes and in skin fibroblasts confirmed monozygosity with a probability of 99.97%. This case is compared with other reported cases of discordance for UTS in twins. It is concluded that essentially all of the differences between the two twins can be explained by loss of an X chromosome early in embryogenesis with complete separation of 45,X and 46,XX cell lineages at the time of the twinning event. The presence of mosaicism in the peripheral blood of both twins is presumably due to anastomoses between the placentae resulting in a mixture of the two cell populations in the hematopoietic tissue.

Original languageEnglish (US)
Pages (from-to)78-82
Number of pages5
JournalAmerican journal of medical genetics
Issue number1
StatePublished - 1991
Externally publishedYes


  • Discordant monozygotic twins
  • anastomoses
  • mosaicism

ASJC Scopus subject areas

  • Genetics(clinical)


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