1/4. Cytogenetic and molecular characterization of two isodicentric Y chromosomes.We report the results of detailed molecular-cytogenetic studies of two isodicentric Y [idic(Y)] chromosomes identified in patients with complex mosaic karyotypes. We used fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) to determine the structure and genetic content of the abnormal chromosomes. In the first patient, classical cytogenetics and FISH analysis with y chromosome-specific probes showed in peripheral blood lymphocytes a karyotype with 4 cell lines: 45,X[128]/46,X, idic(Y)(p11.32)[65]/47,XY, idic(Y)(p11.32)[2]/47,X, 2idic(Y)(p11. 32)[1]. No y chromosome material was found in the removed gonads. For precise characterization of the Yp breakpoint, FISH and fiberFISH analysis, using a telomeric probe and a panel of cosmid probes from the pseudoautosomal region PAR1, was performed. The results showed that the breakpoint maps approximately 1,000 Kb from Ypter. The second idic(Y) chromosome was found in a boy with mild mental retardation, craniofacial anomalies, and the karyotype in lymphocytes 47,X, idic(Y)(q11.23), i(Y)(p10)[77]/46,X, i(Y)(p10)[23]. To our knowledge, such an association has not been previously described. FISH and PCR analysis indicated the presence of at least two copies of the SRY gene in all analyzed cells. Using 17 PCR primers, the Yq breakpoint was shown to map between sY123 (DYS214) and sY121 (DYS212) loci in interval 5O in AZFb region. Possible mechanisms of formation of abnormal Y chromosomes and karyotype-phenotype correlations are discussed.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
2/4. Monozygotic twins with discordant sexual phenotypes due to different ratios of mosaicism of 47,X,idic(Y),idic(Y)/46,X, idic(Y)/45,X.We report monozygotic twins of different sexual phenotypes. One of the twins had complete female external genitalia except for a mild clitoromegaly. She had bilateral gonads consisting of the wavy stroma and scant dysgenetic seminiferous tubules. No androgen secretion was induced by gonadotrophin stimulation. The other twin had hypospadiac male genitalia. His gonads were located intrascrotally and he had good androgenic response to a stimulation test. Conventional and fluorescence in situ hybridization chromosome analysis disclosed that both twins had a 47,X,idic(Y),idic(Y)/46,X,idic(Y)/45,X and 47,X, mar x 2.ish idic(Y)(q11.2)(DYZ3 x 2)/46,X, mar.ish idic(Y)(q11.2)(DZY3 )/45,X. These twins were clinically monochorionic and allelotype analysis in these twins and their parents with microsatellite markers showed the affirmative probability of 0.999999994 for monozygosity. The ratio of mosaicism, gonadal histology, and testosterone productivity were reasonably correlated to the genital virilization in these monozygotic twins, showing discordant sexual phenotypes.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
3/4. True hermaphroditism with 46,X, 22p/46,XY and gonadal mosaicism detected by fluorescence in situ hybridization.A Japanese girl was diagnosed as true hermaphroditism with 46,X, mar/46,XY and the marker chromosome was determined on the short arm of chromosome 22 without alpha-satellite by fluorescence in situ hybridization (FISH) and spectral karyotyping (SKY) methods. At birth, she showed intersexual external genitalia, urethral-vaginal fistula and right inguinal hernia. The right gonad was revealed as an ovotestis, and the left was as an undifferentiated testis. The gonadal mosaicism was demonstrated directly in gonadal tissue by interphase FISH.- - - - - - - - - - ranking = 5keywords = hybridization (Clic here for more details about this article) |
4/4. Mixed gonadal dysgenesis and cell line differentiation. Case presentation and literature review.A male patient with mixed gonadal dysgenesis, involving a streak gonad on the right and a histologically normal testis in the left, was found to have a 45,X/46,X,dic(Yp) chromosome constitution on peripheral blood cultures. fibroblasts grown from both gonads showed the "normal" testicular tissue to have e 45,X/46,X,dic(Yp), whereas the cells from the streak gonad were all 45,X. The structure of the dic(Yp) chromosome was confirmed using non-isotopic in situ hybridization with Y centromere and Yp specific probes. On hormonal stimulation, testosterone levels rose by 50%. The "normal" testis was left in situ, but close follow up will be required in view of the malignant potential.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |