1/80. Sex chromosome aneuploidies in sperm of 47,XYY men.The sex chromosomal equipment in 26,675 sperm of 47,XYY males was analyzed. A total of 5.78% of the nuclei exhibited sex chromosome hyperhaploidy. Six studies have analyzed the sperm of 10 XYY patients and, although these studies indicated some degree of elimination of the extra y chromosome during spermatogenesis, a certain percentage of XYY germinal cells may also be able to achieve meiosis and produce sperm with gonosomal disomies. All these studies show an increased incidence of gonosomal aneuploidies in sperm, but there are significant discrepancies concerning the extent of these abnormalities. The global frequencies of sperm with an abnormal number of sex chromosomes ranged from 0.578 to 13.91%, depending on the patients. There are several explanations for these discrepancies: differences attributed to fluorescence in situ hybridization methodology, the use of dual or multicolor FISH, recruitment, interindividual variations, and intraindividual variations. This study reports an additional series obtained from another XYY individual and compares and discusses the data on gonosomal hyperhaploidies in sperm of 47 XYY males using in situ hybridization analyses.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
2/80. Molecular cytogenetic analysis of a duplication Xp in a female with an abnormal phenotype and random X inactivation.We describe a female infant with severe abnormal phenotype with a de novo partial duplication of the short arm of the X chromosome. chromosome painting confirmed the origin of this X duplication. Molecular cytogenetic analysis with fluorescence in situ hybridization (FISH) was performed with YAC probes, further delineating the breakpoints. The karyotype was 46, X dup(X)(p11-p21.2).Cytogenetic replication studies showed that the normal and duplicated X chromosomes were randomly inactivated in lymphocytes. In most females with structurally abnormal X chromosomes, the abnormal chromosome is inactivated and they are phenotypically apparently normal relatives of phenotypically abnormal males having dupX. Therefore, in this case, there is functional disomy of Xp11-p21.2 in the cells with an active dup(X), most likely resulting in abnormal clinical findings in the patient.- - - - - - - - - - ranking = 0.5keywords = hybridization (Clic here for more details about this article) |
3/80. Loss of the Y chromosomal PAR2-region in four familial cases of satellited Y chromosomes (Yqs).Applying fluorescence in-situ hybridization (FISH) of various Y chromosomal dna probes to four familial cases of human Yqs, it was possible to demonstrate that the formation of Yqs must have arisen from a reciprocal translocation involving the short arm of an acrocentric autosome and the heterochromatin of the long arm of the y chromosome (Yqh). Breakpoints map within Yqh and the proximal short arm of an acrocentric autosome resulting in the gain of a nucleolus organizer region (NOR) including the telomere repeat (TTAGGG)n combined with the loss of the pseudoautosomal region 2 (PAR2) at the long arm of the recipient y chromosome. In no case could the reciprocal product of an acrocentric autosome with loss of the NOR and gain of PAR2 be detected. Using the 15p-specific classical satellite-III probe D15Z1 in two of the four Yqs probands presented here, it could be shown that the satellited material originated from the short arm of chromosome 15. In contrast to the loss of PAR2 in Yqs chromosomes, another Y chromosomal variant (Yqh-) showing deletion of long-arm heterochromatin in Yq12 has retained PAR2 referring to an interstitial deletion of Yq heterochromatin in such deleted Y chromosomes.- - - - - - - - - - ranking = 0.5keywords = hybridization (Clic here for more details about this article) |
4/80. Meiotic behaviour of the sex chromosomes in three patients with sex chromosome anomalies (47,XXY, mosaic 46,XY/47,XXY and 47,XYY) assessed by fluorescence in-situ hybridization.Meiotic studies using multicolour fluorescent in-situ hybridization (FISH) and chromosome painting were carried out in three patients with sex chromosome anomalies (47,XXY; 46,XY/47,XXY and 47,XYY). In the two patients with klinefelter syndrome, although variable percentages of XXY cells (88.5 and 28.3%) could be found in the pre-meiotic stages, none of the abnormal cells entered meiosis, and all pachytenes were XY. However, the abnormal testicular environment of these patients probably resulted in meiotic I non-disjunction, and a certain proportion of post-reductional cells were XY (18.3 and 1.7%). The fact that none of the spermatozoa were XY also suggests the existence of an arrest at the secondary spermatocyte or the spermatid level. In the XYY patient, most (95.9%) premeiotic cells were XYY. The percentage of XYY pachytenes was 57.9%. The sex chromosomes were either in close proximity (XYY) or the X chromosome was separated from the two Ys (X YY). A high proportion (42.1%) of post-reductional germ cells were XY. However, only 0.11% of spermatozoa were disomic for the sex chromosomes. In this case, the data suggest the existence of an arrest of the abnormal cells at the primary and the secondary spermatocyte or the spermatid level, giving rise to the continuous elimination of abnormal cells in the germ-cell line along spermatogenesis. The fact that the proportion of diploid spermatozoa was only increased in one of the three cases (XXY) is also suggestive of an arrest of the abnormal cell lines in these patients. The two apparently non-mosaic patients were, in fact, germ-cell mosaics. This suggests that the cytogenetic criteria used to define non-mosaic patients may be inadequate; thus, the risk of intracytoplasmic sperm injection in apparently non-mosaics may be lower than expected.- - - - - - - - - - ranking = 2.5keywords = hybridization (Clic here for more details about this article) |
5/80. 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 = 0.5keywords = hybridization (Clic here for more details about this article) |
6/80. A case of 46,X,der(X)(pter-->q21::p21-->pter) with gonadal dysgenesis, tall stature, and endometriosis.OBJECTIVE: To report a case of 46,X,der(X)(pter-->q21::p21-->pter) with gonadal dysgenesis, tall stature, and endometriosis. DESIGN: Case report. SETTING: A university hospital. PATIENT(S): A 20-year-old primary amenorrheal woman receiving estrogen-progestogen substitution. INTERVENTION(S): G-banding, comparative genomic hybridization, fluorescence in situ hybridization (FISH), and laparoscopy. MAIN OUTCOME MEASURE(S): A recombinant X chromosome, 46,X,der(X)(pter-->q21::p21-->pter), and pelvic endometriosis. RESULT(S): The patient's chromosomal abnormality was misjudged by the use of G-banding as a distal part deletion of the long arm in one X chromosome. comparative genomic hybridization and fluorescence in situ hybridization analyses with locus-specific probes revealed 46,X,der(X)(pter-->q21::p21-->pter). The laparoscopic examination showed bilateral streak gonads and blue berry spots at the pelvic peritoneum, which were confirmed by evaluation of biopsy specimens. CONCLUSION(S): Recent advances of genetic strategies make it easy to determine karyotype and phenotype abnormalities. We have to keep our mind on the potential of endometriosis with patients who are receiving estrogen-progestogen substitution.- - - - - - - - - - ranking = 2keywords = hybridization (Clic here for more details about this article) |
7/80. prenatal diagnosis of two rare de novo structural aberrations of the y chromosome: cytogenetic and molecular analysis.Two rare de novo structural aberrations of the y chromosome were detected during routine prenatal diagnosis: a satellited non-fluorescent y chromosome (Yqs), the first de novo Yqs to be reported in a fetus, and a terminal deletion of the y chromosome long arm del(Y)(q11). In both cases detailed cytogenetic and molecular analyses were undertaken. In the case of the Yqs it was demonstrated by fluorescence in situ hybridization (FISH) that the satellites were derived from chromosome 15. In the case of the del(Yq), it was shown with molecular analysis by polymerase chain reaction (PCR) amplification of sequence-tagged sites (STS-PCR) that the deleted portion of the long arm of chromosome Y included the azoospermia factor loci, AZFb and AZFc. The clinical significance of these findings is discussed.- - - - - - - - - - ranking = 0.5keywords = hybridization (Clic here for more details about this article) |
8/80. Sex chromosome mosaicism in gonads of a fetus with cystic hygroma and deletion of the short arm of y chromosome including loss of SRY.The SRY gene on the short arm of the y chromosome is necessary for male development. Without SRY, patients with 46,XY karyotype develop as females, fail to achieve normal puberty and have dysgenic gonads and a high incidence of gonadoblastoma. Here we report a female fetus, aborted at 17 weeks of pregnancy, with a non-mosaic 46,X,del(Y)(p11.2).ish del(Y)(SRY-) karyotype diagnosed by classical cytogenetics and fluorescence in situ hybridization (FISH). Ovarian tissue was full of oocytes and mitotic figures. FISH studies of ovarian tissues with X and Y centromere probes revealed extensive sex chromosome mosaicism, manifested by loss of the y chromosome and polysomy of the X chromosome. We propose that X chromosome polysomy is a post-zygotic event that arises to facilitate gonadal differentiation in the absence of all factors necessary for normal gonadal development.- - - - - - - - - - ranking = 0.5keywords = hybridization (Clic here for more details about this article) |
9/80. Familial X centromere variant resulting in false-positive prenatal diagnosis of monosomy X by interphase FISH.interphase fluorescent in situ hybridization (FISH) analysis performed on uncultured amniotic fluid cells from a female fetus revealed a single signal using an X chromosome alpha-satellite probe, and the absence of any signal using a y chromosome alpha-satellite probe. This result was initially interpreted as monosomy for the X chromosome in the fetus. Subsequent chromosome analysis from the cultured amniotic fluid cells showed two apparently normal X chromosomes. FISH using the X alpha-satellite probe on metaphase spreads revealed hybridization to both X chromosomes, although one signal was markedly reduced compared to the other. The same hybridization pattern was observed in the mother of the fetus. This is the first report of a rare familial X centromere variant resulting in a false-positive diagnosis of monosomy X by interphase FISH analysis for prenatal diagnosis.- - - - - - - - - - ranking = 1.5keywords = hybridization (Clic here for more details about this article) |
10/80. Clinical, cytogenetic, and molecular findings in 45,X/47,XX, 18 mosaicism: clinical report and review of the literature.We report cytogenetic and molecular findings performed in a patient with double mosaic aneuploidy. Chromosome analysis of amniotic fluid cells from a 17-week-old fetus was performed because of advanced maternal age. Two karyotypes were detected: 45,X and 47,XX, 18 (50:50%). The same cell lines were determined in uncultured and cultured amniocytes of a second amniotic fluid sample, in fetal lymphocytes, and in uncultured and cultured cells of achilles tendon by conventional cytogenetics and fluorescence in situ hybridization (FISH). In the different investigated tissues, the percentage of cells with 45,X karyotype ranged from 20-99% and the percentage of cells with 47,XX, 18 ranged from 1-80%. The pregnancy was terminated at 22 0 weeks because of a severe cardiac malformation. Pathologic examination showed a fetus with aspects typical for manifestation of trisomy 18 and monosomy X, especially in the internal organs. The parent and cell stage of origin was determined by short tandem repeat typing and revealed a maternal meiotic division error that led to trisomy 18, as well as a somatic loss of a paternal sex chromosome. Only two other patients with the same mosaicism have been reported so far. genetic counseling and prognosis remains challenging.- - - - - - - - - - ranking = 0.5keywords = hybridization (Clic here for more details about this article) |
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