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

Abstract

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.

Prevalência de sequências do Y e de gonadoblastoma em síndrome de Turner

“…The frequency of gonadoblastoma in TS patients with positive amplification for Y-chromosome is summarized in Table 3, with information on gonadectomy and gonadoblastoma in TS in 9 of 14 studies. The results of five studies3 , 14 , 15 , 17 , 21 are not included in Table 3 for the following reasons: (1) two studies had no information on gonadectomy and gonadoblastoma in the text3 , 21; (2) in two studies patients were scheduled for clinical follow-up17 or monitoring by a multidisciplinary team of biologist, psychologist, geneticist, endocrinologist, and gynecologist14; and (3) in one study prophylactic gonadectomy was offered to all patients with Y sequences, however, the same patients opted for regular monitoring by ultrasound and CT 15…”

“…Essa apresenta informações sobre gonadectomia e gonadoblastoma em ST em nove dos 14 estudos. Os resultados de cinco estudos não constam na tabela 3 3 , 14 , 15 , 17 , 21 pelos seguintes motivos: 1 –dois estudos não apresentaram informações sobre gonadectomia e gonadoblastoma no texto;3 , 21 2 – em dois, os pacientes foram agendados para seguimento clínico17 ou acompanhamento por equipe multidisciplinar composta por biólogo, psicólogo, geneticista, endocrinologista e ginecologista14 e 3 – no outro estudo, a gonadectomia profilática foi oferecida a todas as pacientes que apresentaram sequências do Y, entretanto, as mesmas optaram por acompanhamento periódico por ultrassonografia e tomografia 15…”

“…, 9 – 15 Four have been published by the same group and the two studies reporting a higher prevalence of Y-chromosome sequences9 – 12 analyzed samples from different tissues (peripheral blood, oral mucosa cells, and hair root) 910 One study evaluated 20 patients with TS and karyotype 45,X9 and the other 5 patients with chromosomal abnormalities, such as chromosome marker, additional material, or ring chromosome 10.…”

“…, 15 In four TS patients, the detection of Y-chromosome sequences was identified only by PCR [karyotypes: 45,X and 46,X,i(Xq)] 1415 Thus, the inclusion of PCR technique in TS routine investigation would be indicated 14. It is noteworthy that six Brazilian studies have used only the PCR technique for the investigation of Y-chromosome sequences.…”

“…, 9 - 15 Quatro foram publicados pelo mesmo grupo de pesquisadores9 - 12 e os dois que relataram maior prevalência de sequências do cromossomo Y analisaram amostras de diferentes tecidos (sangue periférico, células de mucosa oral e raiz de cabelo) 910 Um deles avaliou 20 pacientes com ST e cariótipo 45,X9 e o outro, cinco com anomalias cromossômicas, tais como cromossomo marcador, material adicional ou cromossomo em anel 10.…”