Y chromosome in Turner syndrome: review of the literature / Cromossomo Y na síndrome de Turner: revisão da literatura

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 percent 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 percent 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 percent), 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.

A 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 por cento 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 por cento 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 por cento) 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, independentemente do seu cariótipo, é necessária para prevenir o desenvolvimento de lesões gonadais.

Prevalence of the polymorphism MTHFR A1298C and not MTHFR C677T is related to chromosomal aneuploidy in Brazilian Turner Syndrome patients / A prevalência do polimorfismo A1298C e não do C677T do gene MTHFR está relacionada à ocorrência de aneuploidias cromossômicas em mulheres brasileiras portadoras da síndrome de Turner

BACKGROUND: Dysfunctions in the folate metabolism can result in DNA hypomethylation and abnormal chromosome segregation. Two common polymorphisms of this enzyme (C677T and A1298C) reduce its activity, but when associated with aneuploidy studies the results are conflicting. The objective of the present study is to analyze the MTHFR gene polymorphisms in women with Turner Syndrome and in a control group, correlating the findings to the chromosomal aneuploidy. METHODS: The study comprised 140 patients with Turner Syndrome, of which 36 with chromosome mosaicism and 104 non-mosaics, and a control group of 209 fertile and healthy women without a history of any offspring with aneuploidy. Polymorphisms C677T and A1298C were studied by RFLP-PCR and the results were statistically analyzed. RESULTS: The frequency of genotypes MTHFR 677CC, 677CT and 677TT in the patients with Turner Syndrome and chromosome mosaicism was, respectively, 58.3 percent, 38.9 percent and 2.8 percent. Among the patients with non-mosaic Turner Syndrome, 47.1 percent presented genotype 677CC, 45.2 percent genotype 677CT, and 7.7 percent genotype 677TT. Among the 209 individuals of the control group, genotypes 677CC, 677CT and 677TT were found at the following frequencies: 48.3 percent, 42.1 percent and 9.6 percent, respectively. As for polymorphism A1298C, the patients with Turner Syndrome and chromosome mosaicism presented genotypes 1298AA, 1298AC and 1298CC at the following frequencies: 58.3 percent, 27.8 percent and 13.9 percent, respectively. Among the non-mosaic Turner Syndrome patients, genotype 1298AA was found in 36.5 percent, genotype 1298AC in 39.4 percent, and genotype 1298CC in 22.1 percent. In the control group, genotypes 1298AA, 1298AC and 1298CC were present at the following frequencies: 52.6 percent, 40.7 percent and 6.7 percent, respectively. CONCLUSION: No correlation was observed between the MTHFR gene polymorphism 677 and chromosomal aneuploidy in the...

INTRODUÇÃO: Disfunções no metabolismo dos folatos podem resultar em hipometilação do DNA e na segregação cromossômica anormal. Dois polimorfismos comuns no gene MTHFR (C677T e A1298C) reduzem a atividade da enzima e, quando associados a estudos de aneuploidias apresentam resultados conflitantes. O objetivo do presente estudo foi a análise dos polimorfismos do gene MTHFR em mulheres portadoras da síndrome de Turner e em indivíduos de grupo-controle, correlacionando os achados ao mecanismo de formação de aneuploidias cromossômicas. MÉTODOS: Foram estudadas 140 portadoras da síndrome de Turner sendo 36 com mosaicismo cromossômico e 104 não-mosaicos, e um grupo-controle composto por 209 mulheres férteis e saudáveis sem história de prole com aneuplodia. Os polimorfismos MTHFR C677T e A1298C foram estudados por RFLP-PCR e os resultados analisados estatisticamente. RESULTADOS: A freqüência dos genótipos MTHFR 677CC, 677CT e 677TT nas pacientes portadoras de síndrome de Turner e mosaicismo cromossômico foi, respectivamente, 58,3 por cento, 38,9 por cento e 2,8 por cento. Das pacientes portadoras de síndrome de Turner não-mosaico, 47,1 por cento apresentaram o genótipo 677CC, 45,2 por cento o genótipo 677CT e 7,7 por cento apresentaram o genótipo 677TT. Nos 209 indivíduos do grupo-controle, os genótipos 677CC, 677CT e 677TT foram encontrados nas seguintes freqüências: 48,3 por cento, 42,1 por cento e 9,6 por cento, respectivamente. Quanto ao polimorfismo A1298C, as portadoras de síndrome de Turner e mosaicismo cromossômico apresentaram os genótipos 1298AA, 1298AC e 1298CC nas seguintes freqüências: 58,3 por cento, 27,8 por cento e 13,9 por cento, respectivamente. Já nas portadoras de Síndrome de Turner não-mosaico, o genótipo 1298AA foi encontrado em 36,5 por cento, o genótipo 1298AC em 39,4 por cento e o genótipo 1298 CC em 22,1 por cento . No grupo-controle, os genótipos 1298AA, 1298AC e 1298CC estavam presentes nas freqüências 52,6 por cento...

Comparison of positivity frequency of bcl-2 expression in prostate adenocarcinoma with low and high Gleason score

CONTEXT: Multiple genetic and epigenetic factors have been implicated in the oncogenesis and progression of prostate cancer. The major difficulty is in that the clinical management stems from the reality that reliable and accurate prognostic biomarkers are not available and that effective treatment regimens forming hormone-resistant prostate cancers are yet to be developed. Among the most important regulators of apoptosis and programmed cell death is the bcl-2 gene and its related proteins. Elevated levels of bcl-2 protein may contribute to the progression of prostate cancers to a metastatic and hormone-insensitive state characterized by poor responses to chemotherapy. OBJECTIVE: To characterize the expression of bcl-2 proteins as a prognostic factor in humans. DESIGN: A retrospective approach. SETTING: Urology section, Federal University of Säo Paulo. DIAGNOSTIC TEST USED: Immunohistochemical analysis using bcl-2 protein antibody and normal staining by hematoxylin-eosin. MAIN MEASUREMENTS: Prognostic relations and protein expression were evaluated considering the total sample (28) divided into two groups, high (8 to 10) and low (2 to 4), separated according to the histological differentiation grade (Gleason score) with 10 and 18 samples, respectively. RESULTS: The differentiation of grade into two groups separated according to the Gleason score in low and high types presented different bcl-2 expression (P < 0.001). CONCLUSION: The higher frequency of bcl-2 immunostaining in tumor samples was observed in association with more advanced Gleason scores and suggests that an increase in the ratio of this anti-apoptotic protein often occurs during progression of prostate cancers