Y chromosome in Turner syndrome: detection of hidden mosaicism and the report of a rare X;Y translocation case

Turner syndrome (TS) is a common genetic disorder in females associated with the absence of complete or parts of a second sex chromosome. in 5-12% of patients, mosaicism for a cell line with a normal or structurally abnormal Y chromosome is identified. the presence of Y-chromosome material is of medical importance because it results in an increased risk of developing gonadal tumours and virilisation. Molecular study and fluorescence in situ hybridisation approaches were used to study 74 Brazilian TS patients in order to determine the frequency of hidden Y-chromosome mosaicism, and to infer the potential risk of developing malignancies. Additionally, we describe one TS girl with a very uncommon karyotype 46,X,der(X)t(X;Y)(p22.3?2;q11.23) comprising a partial monosomy of Xp22.3?2 together with a partial monosomy of Yq11.23. the presence of cryptic Y-chromosome-specific sequences was detected in 2.7% of the cases. All patients with Y-chromosome-positive sequences showed normal female genitalia with no signs of virilisation. Indeed, the clinical data from Y-chromosome-positive patients was very similar to those with Y-negative results. Therefore, we recommend that the search for hidden Y-chromosome mosaicism should be carried out in all TS cases and not be limited to virilised patients or carriers of a specific karyotype.Fundacao de Amparo a Ciencia e Tecnologia do Estado de PernambucoUniv Fed Pernambuco, Dept Genet, BR-50740600 Recife, PE, BrazilInst Med Integral Prof Fernando Figueira IMIP, Lab Pesquisa Translac Prof C Anthony Hart, BR-50070050 Recife, PE, BrazilInst Med Integral Prof Fernando Figueira IMIP, Unidade Genet Pediat, BR-50070050 Recife, PE, BrazilHosp Clin HC UFPE, Unidade Endocrinol Pediat, BR-50740600 Recife, PE, BrazilHosp Oswaldo Cruz UPE, Ctr Oncohematol Pediat Pernambuco, BR-50100130 Recife, PE, BrazilUniversidade Federal de São Paulo UNIFESP, Lab Erros Inatos Metab EIM, BR-04021001 São Paulo, BrazilInst Ciencias Biol, BR-50100130 Recife, PE, BrazilUniv Jena, Jena Univ Hosp, Inst Human Genet, D-07743 Jena, GermanyUniversidade Federal de São Paulo UNIFESP, Lab Erros Inatos Metab EIM, BR-04021001 São Paulo, BrazilFundacao de Amparo a Ciencia e Tecnologia do Estado de Pernambuco: FACEPE - APQ-0335-2.02/06Web of Scienc