1/12. Identification of Y chromatin directly in gonadal tissue by fluorescence in situ hybridization (FISH): significance for Ullrich-turner syndrome screening in the cytogenetics laboratory.The presence of Y chromatin in individuals with Ullrich-turner syndrome (UTS) confers a risk for gonadoblastoma. In mosaic cases, little is known about Y chromatin distribution in gonads. fluorescence in situ hybridization (FISH) is a direct approach to assess the extent of Y chromatin mosaicism in gonads. Gonadal tissue from four patients with mosaic karyotypes were analyzed by routine cytogenetics and FISH with X and Y centromere probes. Y chromatin was present in gonads in varying percentages in these patients. The distribution of Y chromatin in gonads of UTS individuals did not completely correlate with that found in blood lymphocytes. The finding of Y chromatin in the blood samples from these patients prompted the development of a screening strategy in our cytogenetics laboratory to detect low-level Y chromatin mosaicism in patients with UTS.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
2/12. Cardio-facio-cutaneous syndrome phenotype in an individual with an interstitial deletion of 12q: identification of a candidate region for CFC syndrome.We report on a 19-month-old girl who presented with the phenotype of cardio-faciocutaneous (CFC) syndrome including characteristic minor facial anomalies, cardiac defect, ectodermal anomalies, and developmental delay. cytogenetic analysis showed the presence of an interstitial deletion of one chromosome 12, del(12)(q21.2q22), confirmed by fluorescence in situ hybridization with chromosome band specific probes. Controversy exists as to whether CFC and noonan syndrome (NS) are distinct disorders, a contiguous gene syndrome, or allelic variants. The identification of the del(12) in this patient, in a region distinct from the putative NS locus, supports the view that CFC is a genetically distinct condition from NS. In addition, this implicates the region 12q21.2-->4q22 as a candidate region for the gene(s) causing CFC syndrome.- - - - - - - - - - ranking = 0.2keywords = hybridization (Clic here for more details about this article) |
3/12. Ullrich-turner syndrome in an XY female fetus with deletion of the sex-determining portion of the y chromosome.Here we describe a fetus in whom a cystic hygroma was detected by ultrasound during the second trimester. autopsy demonstrated a female fetus with manifestations of Ullrich-turner syndrome, including gonadal dysgenesis, generalized lymphedema, and preductal aortic coarctation. Surprisingly, the karyotype was 46,XY, with no evidence of mosaicism for a 45,X cell line. Y-DNA hybridization studies demonstrated a deletion of the sex-determining segment of the short arm of the y chromosome. This is the first report, in a fetus, of XY Ullrich-turner syndrome due to a Y chromosome deletion.- - - - - - - - - - ranking = 0.2keywords = hybridization (Clic here for more details about this article) |
4/12. 45X/46X,r(X) with syndactyly and severe mental retardation.Two white females, age 2 1/2 and 33 years, respectively, were investigated because of severe mental retardation associated with neurologic abnormalities, coarse face, and soft tissue syndactyly involving upper and lower limbs. Each had cytogenetic findings of a mosaic variant of Ullrich-turner syndrome with X ring chromosome in peripheral lymphocyte and skin fibroblasts. Early X replication occurred in one-third of the X ring chromosomes; there was no evidence for X-autosome translocation involving either X and an autosomal duplication; results of studies for fragility of the X chromosomes were unremarkable. in situ hybridization with an X centromere probe was positive for the ring. To our knowledge, the unusual constellation of cytogenetic, physical, and mental findings seen in these 2 individuals has not been reported previously.- - - - - - - - - - ranking = 0.2keywords = hybridization (Clic here for more details about this article) |
5/12. A 45,X male with a Yp/18 translocation.A patient described as a 45,X male (Forabosco et al. 1977) was examined for the presence of Y-specific DNA by using various probes detecting restriction fragments from different regions of the y chromosome. Positive hybridization signals were obtained for Yp fragments only. in situ hybridization with two different probes, pDP31 and the pseudoautosomal probe 113F, led to a clear assignment of the Yp sequences to the short arm of one chromosome 18. Cytogenetically, the presence of all of Yp including the Y centromere on 18p could be demonstrated replacing a segment of similar size of 18p. Thus, the Y/18 translocation chromosome is dicentric structurally, but it was shown to be monocentric functionally with the no. 18 centromere active. gene dosage studies with the probe B74 defining a sequence at 18p11.3 demonstrated a single dose of this sequence in the patient. In agreement with these observations, the patient shows clinical signs of the 18p-syndrome. It is concluded that in XO males in general, the X is of maternal origin while the maleness is due to a de novo Y/autosome translocation derived from the father. Depending on the nature of the autosomal deficiency caused by the Y/autosome translocation, the patient may have congenital malformations.- - - - - - - - - - ranking = 0.4keywords = hybridization (Clic here for more details about this article) |
6/12. Three cases of 45,X/46,XYnf mosaicism. Molecular analysis revealed heterogeneity of the nonfluorescent y chromosome.Three patients with 45,X/46,XYnf mosaicism were investigated by Southern hybridization using both X- and Y-specific dna probes. Our patients seem to be hemizygous for the X chromosomal loci tested. Single-copy and low-copy repeated Y chromosomal sequences assigned to the short arm, centromere, and euchromatin of the long arm have been detected in our patients, suggesting the Y chromosomal origin of the marker chromosome both in male and female cases studied. densitometry of autoradiographs revealed a double dose of Yp-specific fragments of the DXYS1 locus. None of the patients tested showed either the 3.4- or the 2.1-kb Hae III male-specific repeated DNA sequences. It seems likely that the Ynf is a pseudodicentric chromosome with duplication of Yp and euchromatic Yq sequences, the Yq heterochromatin being lost. Our findings indicate structural heterogeneity of the marker chromosome and in addition provide further information on the relative position of DNA sequences detected by dna probes 50f2, M1A, and pDP105.- - - - - - - - - - ranking = 0.2keywords = hybridization (Clic here for more details about this article) |
7/12. Y;autosome translocations and mosaicism in the aetiology of 45,X maleness: assignment of fertility factor to distal Yq11.Three 45,X males have been studied with Y-dna probes by Southern blotting and in situ hybridization. Southern blotting studies with a panel of mapped Y-dna probes showed that in all three individuals contiguous portions of the y chromosome including all of the short arm, the centromere, and part of the euchromatic portion of the long arm were present. The breakpoint was different in each case. The individual with the largest portion (intervals 1-6) is a fertile male belonging to a family in which the translocation is inherited in four generations. The second adult patient, who has intervals 1-5, is an azoospermic, sterile male. These phenotypic findings suggest the existence of a gene involved in spermatogenesis in interval 6 in distal Yq11. The third case, a boy with penoscrotal hypospadias, has intervals 1-4B. in situ hybridization with the pseudoautosomal probe pDP230 and the y chromosome specific probe pDP105 showed that Y-derived DNA was translocated onto the short arm of a chromosome 15, 14, and 14, respectively. One of the patients was a mosaic for the 14p translocation chromosome. Our data and those reported by others suggest the following conclusions based on molecular studies in eight 45,X males: The predominant aetiological factor is Y;autosome translocation observed in seven of the eight cases. As the remaining case was a low-grade mosaic involving a normal y chromosome, the maleness in all cases was due to the effect of the testis determining factor, TDF. There is preferential involvement of the short arm of an acrocentric chromosome (five out of seven translocations) but other autosomal regions can also be involved. The reason why one of the derivative translocation chromosomes becomes lost may be that it has no centromere.- - - - - - - - - - ranking = 0.4keywords = hybridization (Clic here for more details about this article) |
8/12. Molecular detection of a Yp/18 translocation in a 45,X holoprosencephalic male.prenatal diagnosis in a fetus with holoprosencephaly showed a 45,X karyotype and a suspected 18p abnormality. At birth, the fetus presented with normal male genitalia. Y chromatin was not cytogenetically detectable by Q-, G-, or G11-banding. mosaicism for a cell line containing a y chromosome was not observed in amniocytes, lymphocytes, or skin fibroblasts. Southern blot analysis for 11 different Y-DNA loci demonstrated the presence in the patient's genome of sequences derived from the short arm, centromeric region, and proximal long arm of the y chromosome (intervals 1-5). The distal long arm of the Y (intervals 6 and 7) was absent. in situ hybridization with the Y-derived probe pDP105 showed silver grains over the short arm of the del(18) chromosome, suggesting a Y/18 translocation with loss of 18p and distal Yq material.- - - - - - - - - - ranking = 0.2keywords = hybridization (Clic here for more details about this article) |
9/12. A 45,X male with Y-specific DNA translocated onto chromosome 15.A 20-year-old male patient with chromosomal constitution 45,X, testes and normal external genitalia was examined. Neither mosaicism nor a structurally aberrant Y chromosome was observed when routine cytogenetic analysis was performed on both lymphocytes and skin fibroblasts. y chromosome-specific single-copy and repeated DNA sequences were detected in the patient's genome by means of 11 different recombinant-dna probes of known regional assignment on the human y chromosome. Data indicated that the short arm, the centromere, and part of the long-arm euchromatin of the y chromosome have been retained and that the patient lacks deletion intervals 6 and 7 of Yq. High-resolution analysis of prometaphase chromosomes revealed additional euchromatic material on the short arm of one of the patient's chromosomes 15. After in situ hybridization with the y chromosome-specific probe pDP105, a significant grain accumulation was observed distal to 15p11.2, suggesting a Y/15 chromosomal translocation. We conclude that some 45,X males originate from Y-chromosome/autosome translocations following a break in the proximal long arm of the y chromosome.- - - - - - - - - - ranking = 0.2keywords = hybridization (Clic here for more details about this article) |
10/12. Molecular detection of a translocation (Y;15) in a 45,X male.A 45,X male individual was shown to have a translocation of Y-chromosome material to the short arm or proximal long arm of chromosome 15. This translocation was detected by genomic DNA blotting and in situ hybridization with Y-chromosome-specific dna probes.- - - - - - - - - - ranking = 0.2keywords = hybridization (Clic here for more details about this article) |
| | Next -> |