Turner syndrome (TS) is one of the most common types of aneuploidy among humans, and is present in 1:2000 newborns with female phenotype.Cytogenetically, the syndrome is characterized by sex chromosome monosomy (45,X), which is present in 50-60% of the cases. The other cases present mosaicism, with a 45,X cell line accompanied by one or more other cell lines with a complete or structurally abnormal X or Y chromosome. The presence of Y-chromosome material in patients with dysgenetic gonads increases the risk of gonadal tumors, especially gonadoblastoma. The greatest concern is the high risk of developing gonadoblastoma or other tumors and virilization during puberty if chromosome Y-specific sequences are present. The role of the Y chromosome in human oncogenesis is still controversial. Even though gonadoblastoma is a benign tumor, it can undergo transformation into invasive dysgerminoma in 60% of the cases, and also into other, malignant forms of germ cell tumors. Although some authors have questioned the high incidence of gonadoblastoma (around 30%), the risk of developing any kind of gonadal lesion, whether tumoral or not, justifies investigation of Y-chromosome sequences by means of the polymerase chain reaction (PCR), a highly sensitive, low-cost and easy-to-perform technique. In conclusion, mosaicism of both the X and the Y chromosome is a common finding in TS, and detection of Y-chromosome-specific sequences in patients, regardless of their karyotype, is necessary in order to prevent the development of gonadal lesions. RESUMOA síndrome de Turner (ST) é uma das aneuploidias mais comuns em humanos e está presente em 1:2000 recém-nascidas com fenótipo feminino.Citogeneticamente, a síndrome é caracterizada por uma monossomia de cromossomo sexual (45,X) em 50-60% dos casos. Os demais casos apresentam mosaicismo com uma linhagem celular 45,X acompanhada de outra(s) com o cromossomo X ou Y íntegros ou com alterações estruturais. A presença de material do cromossomo Y em pacientes com gônadas disgenéticas aumenta o risco de tumores gonadais, especialmente gonadoblastoma. A consideração mais importante diz respeito ao elevado risco de desenvolvimento de gonadoblastoma ou outros tumores e a virilização na puberdade se sequências cromossomo Y-específicas estiverem presentes. O papel do cromossomo Y na oncogênese dos cânceres humanos ainda é controverso.Apesar de o gonadoblastoma ser um tumor benigno, ele pode transformar-se num disgerminoma invasivo em 60% dos casos e também em outras formas malignas de tumores de células germinativas. Apesar de alguns autores questionarem a alta incidência (em torno de 30%) de gonadoblastoma, o risco do desenvolvimento de qualquer tipo de lesão gonadal, tumoral ou não, justifica a pesquisa de sequências do cromossomo Y por PCR (reação de polimerase em cadeia), técnica de alta sensibilidade, baixo custo e fácil execução. Em conclusão, o mosaicismo cromossômico tanto do X como do Y é um fato comum na ST e a detecção de sequências cromossomo Y-específicas nas portadoras, indepen...

A systematic search for hidden Y chromosome mosaicism in patients with TS and 45,X karyotype is justified by the possibility of developing gonadoblastoma.

Objective: Wolfram syndrome (WS) is a rare, progressive, neurodegenerative disorder with an autosomal recessive pattern of inheritance. The gene for WS, WFS1, was identified on chromosome 4p16 and most WS patients carry mutations in this gene. However, some studies have provided evidence for genetic heterogeneity and the genotype-phenotype relationships are not clear. Our aim was to ascertain the spectrum of WFS1 mutations in Brazilian patients with WS and to examine the phenotype-genotype relationships in these patients. Design and methods: Clinical characterization and analyses of the WFS1 gene were performed in 27 Brazilian patients with WS from 19 families. Results: We identified 15 different mutations in the WFS1 gene in 26 patients, among which nine are novel. All mutations occurred in exon 8, except for one missense mutation which was located in exon 5. Although we did not find any clear phenotype-genotype relationship in patients with mutations in exon 8, the homozygous missense mutation in exon 5 was associated with a mild phenotype: onset of diabetes mellitus and optic atrophy during adulthood with good metabolic control being achieved with low doses of sulfonylurea. Conclusions: Our data show that WFS1 is the major gene involved in WS in Brazilian patients and most mutations are concentrated in exon 8. Also, our study increases the spectrum of WFS1 mutations. Although no clear phenotype-genotype relationship was found for mutations in exon 8, a mild phenotype was associated with a homozygous missense mutation in exon 5.

The presence of Y-chromosome material in patients with dysgenetic gonads increases the risk of gonadal tumors and/or nontumoral androgen-producing lesions. The patients' prognosis can vary, depending on their karyotype. The objective of this study was to investigate the presence of Y-chromosome mosaicism in Turner syndrome patients and its association with the development of gonadal tumors and/or nontumoral androgen-producing lesions. Eighty-seven Turner syndrome patients were studied. Genomic DNA was extracted from peripheral blood and genes SRY and TSPY and DYZ3 repeat of the Y chromosome were amplified by polymerase chain reaction. To the Y-positive patients, prophylactic gonadectomy was offered. The data disclosed hidden Y-chromosome mosaicism in 16 (18.5%) of the patients. SRY sequence was detected in all of the 16 patients, and 4 (4.6%) of them presented DYZ3 repeat region and TSPY gene. Eleven of the patients with Y-positive sequences agreed to undergo the prophylactic surgery. In 2 cases, bilateral gonadoblastoma was found and, in another case, the histopathologic study of the gonads revealed hilus cell hyperplasia. In a further case, there were hilus cell hyperplasia and a stromal luteoma. In conclusion, a systematic search for hidden Y-chromosome mosaicism, especially SRY, in Turner syndrome patients is justified by the possibility of preventing gonadal lesions.