Molecular mapping of an idic(Yp) chromosome in an Ullrich‐Turner patient

We describe a woman with Ullrich‐Turner manifestations and a 45,X/46,X,+mar karyotype. Fluorescence in situ hybridization (FISH) and DNA analysis were carried out in order to determine the origin and structure of the marker. FISH showed that the marker was a Y‐derived dicentric chromosome. The breakpoint at Yq11 (interval 6) was mapped using Southern blotting and polymerase chain reaction (PCR). There were no nucleotide alterations in the SRY conserved domain. Histological analysis of the gonads showed an ovarian‐like stroma with no signs of testicular tissue. These findings indicate that the patient was a mosaic 45,X/46,X,idic(Yp) whose phenotypic expression, including sex determination, appeared to have had more influence from the 45,X cell line. Am. J. Med. Genet. 91:95–98, 2000. © 2000 Wiley‐Liss, Inc.     

Isodicentric Y chromosome in an Ullrich‐Turner patient without virilization

We report on a 17‐year‐old young woman with Ullrich‐Turner syndrome (UTS), who was found to have a karyotype 45,X/46,X,idic(Y)(q11). She had age‐appropriate genitalia without virilization in spite of the presence of the Y‐derived marker chromosome and SRY locus in 70% of her lymphocytes. Having reviewed the literature, we conclude that a possible explanation for the lack of virilization in these mosaic patients is most likely an uneven distribution of tissue mosaicism (gonadal mosaicism). Am. J. Med. Genet. 91:99–101, 2000. © 2000 Wiley‐Liss, Inc.     

Turner syndrome patients with a ring X chromosome

A patient with clinical features of Turner syndrome and a 45,X karyotype in repeated blood cultures was re-evaluated when she spontaneously entered puberty. A ring X cell line was found in a small proportion of fibroblasts. A review of 35 previously published ring X cases is presented. All are mosaic, the major cell line in most cases being 45,X. There is wide variation in the frequency with which the abnormalities associated with Turner syndrome are found in these patients. All have short stature. Some are sexually developed and fertile. Cardiovascular anomalies are uncommon. This phenotypic variation may have at least two causes: the size of the deleted portion at each end of the X chromosome, and the relative frequency and distribution of 45,X and 46,X,r(X) cell lines in various body tissues.     

Short bi‐iliac distance in prenatal Ullrich‐Turner syndrome

The purpose of the present study is to evaluate the bi‐iliac distance and the caudo‐cranial position of the iliac bones in Ullrich‐Turner syndrome (UTS) fetuses compared to recently published standards for normal fetuses. Whole‐body radiographs in antero‐posterior projections of 24 UTS fetuses (crown‐rump lengths, 106–220 mm) were included in the study. From each radiograph, two horizontal (outer and inner bi‐iliac distances) and two vertical (caudo‐cranial) positions compared to the vertebral column were measured to estimate the position of the iliac bones. The present investigation revealed that both the outer and inner bi‐iliac distances were significantly shorter in UTS fetuses than in normal fetuses. We also found that for the inner bi‐iliac distance, the growth rate in UTS fetuses was significantly lower than in normal fetuses. This finding suggests not only a lesser growth but also a different growth pattern compared to normal fetuses. Regarding the caudo‐cranial position of the iliac bones compared to the lower vertebral column, there was no significant difference for the lower caudo‐cranial position, but the upper caudo‐cranial position was significantly lower in UTS fetuses than in normal fetuses. The bi‐iliac distance and the iliac bone position have not previously been described in Ullrich‐Turner syndrome fetuses. © 2002 Wiley‐Liss, Inc.     

Clinical update on sensorineural hearing loss in Turner syndrome and the X‐chromosome

Hearing loss is one of the major medical concerns in girls and women with Turner syndrome (TS) and has a negative effect on well‐being and quality of everyday life. Sensorineural hearing loss is the most common type of hearing loss, affecting more than half of adults with TS. Karyotypes with a loss of the short p‐arm on the X‐chromosome are more prone to ear and hearing problems. The importance of detecting, investigating, and treating hearing loss with hearing aids cannot be emphasized enough. The pathophysiology of the sensorineural hearing loss in TS is not known, but theories regarding estrogen deficiency, the cell cycle delay hypothesis, IGF‐1 deficiency and the possible role of the KDM6A gene are discussed. Due to the diversity of symptoms and conditions within the same karyotype, a combination of genetic factors altered by epigenetic and/or hormonal effects is probable. Further research is needed regarding the pathophysiology of ear and hearing problems in TS to develop new treatment methods.     

Detection and incidence of cryptic Y chromosome sequences in Turner syndrome patients

The presence of Y chromosome sequences in Turner syndrome (TS) patients may predispose them to gonadoblastoma formation with an estimated risk of 15–25%. The aim of this study was to determine the presence and the incidence of cryptic Y chromosome material in the genome of TS patients. The methodology involved a combination of polymerase chain reaction (PCR) and nested PCR followed by Southern blot analysis of three genes—the sex determining region Y (SRY), testis specific protein Y encoded (TSPY) and RNA binding motif protein (RBM) (previously designated as YRRM) and nine additional STSs spanning all seven intervals of the Y chromosome. The methodology has a high sensitivity as it detects one 46, XY cell among 10⁵ 46, XX cells. Reliability was ensured by taking several precautions to avoid false positive results. We report the results of screening 50 TS patients and the identification of cryptic Y chromosome material in 12 (24%) of them. Karyotypes were divided in four groups: 5 (23.8%) patients out of the 21 TS patients which have the 45, X karyotype (group A) also have cryptic Y sequences; none (0%) of the 7 patients who have karyotypes with anomalies on one of the X chromosomes have Y mosaicism (group B); 1 (6.3%) of the 16 patients with a mosaic karyotype have Y material (group C); and 6 (100%) out of 6 patients with a supernumerary marker chromosome (SMC) have Y chromosome sequences (group D). Nine of the 12 patients positive for cryptic Y material were recalled for a repeat study. Following new DNA extraction, molecular analysis was repeated and, in conjunction with fluorescent in situ hybridization (FISH) analysis using the Y centromeric specific probe Yc-2, confirmed the initial positive DNA findings. This study used a reliable and sensitive methodology to identify the presence of Y chromosome material in TS patients thus providing not only a better estimate of a patient's risk in developing either gonadoblastoma or another form of gonadal tumor but also the overall incidence of cryptic Y mosaicism.     

Parental origin of the X chromosome, X chromosome mosaicism and screening for "hidden" Y chromosome in 45,X Turner syndrome ascertained cytogenetically

Our study confirms the finding that about 85% of X chromosomes in Turner girls are maternally derived. A new observation is the detection of a high frequency of mosaicism (15%) in Turner girls who by cytogenetic analysis were thought to have a pure 45,X karyotype. DNA examination of the material was done by hybridization with digoxigenin labelled, non-radioactive probes, and PCR products for microsatellite analysis were run on polyacrylamide gels. We screened for the presence of "hidden" Y chromosome mosaicism, using the primers SRY, ZFY, DYZ3, DYZ1 and DYS132. Contrary to other reports using the PCR technique to unravel "hidden" Y chromosome mosaics, we did not find any positive cases. A precise technical protocol for these new techniques is given, and the advantages are discussed.     

Detection of Y‐specific sequences in 122 patients with Turner syndrome: Nested PCR is not a reliable method

The incidence of Y chromosome sequences in patients with Turner syndrome has been evaluated in several studies, and its frequency varied from 0% to 61%, depending on the molecular methodology used. The aim of our study was to screen for Y chromosome sequences in 122 patients with Turner syndrome without cytogenetic evidence of this chromosome. DNA of 100 normal women was also screened and it was used as a negative control. To identify cryptic Y mosaicism, eight regions of Y chromosome were amplified by PCR. In order to increase the sensitivity of Y sequence detection, a nested PCR of the SRY and TSPY genes was also performed. All patients had several stigmata of Turner syndrome and none of them presented with signs of virilization. The most frequent karyotype was 45,X (54.1%), followed by mosaicism involving structural aberration of the X chromosome. There were 12 patients who carried a marker or ring chromosome. First‐round PCR identified Y chromosome sequences in only four patients (3%), and all of them had a chromosome mosaicism with at least one cell lineage with a marker chromosome. After nested PCR, 25% of the patients and 14% of the normal women were positive for the presence of Y sequences. Contamination with extraneous genomic DNA was ruled out by microsatellite studies, but we cannot eliminate the possibility of contamination with PCR products, despite careful handling. We conclude that nested PCR overestimated the frequency of Y sequences in patients with Turner syndrome and should be avoided to prevent false positive results, which lead to unnecessary surgical treatment of these patients. © 2001 Wiley‐Liss, Inc.     

Ring chromosome X in a child with manifestations of Kabuki syndrome

A female patient with the karyotype 45, X/46, X, r(X)(p11.2 q13) and severe developmental delay, prominent fingertip pads, long palpebral fissures, short stature, and history of hypotonia had a phenotype reminiscent of Kabuki syndrome. We hypothesized that overexpression of X chromosome-derived sequences might be associated with the Kabuki-like phenotype observed. The nature and parental origin of this small-ring X were ascertained using a combination of genotyping with microsatellite markers and quantitative Southern blotting. PCR-based genotyping demonstrated heterozygosity at X-linked loci SBMA (Xq11-q12) and DXS227 (Xq13.1). Hemizygosity was observed at several loci: DMD STR-49 (Xp21.2), DXS1003 (Xp 11.23), DXS988 (Xp 11.21), DXS101 (Xq21.3), FMR-1 (Xq27.3), and DXYS64 (Xq28). This ring X chromosome is paternally derived since only maternal alleles are inherited at three informative microsatellite loci. Results of FISH and RT-PCR experiments indicate that the XIST locus is missing in the ring X chromosome and not expressed. These data indicated a large deletion of the X chromosome consistent with a small-ring X chromosome with approximate breakpoints near p11.2 and q13. These results are comparable to the observation of others where an atypically severe phenotype has been associated with the presence of an r(X), or small mar(X). Am. J. Med. Genet. 70:37–42, 1997. © 1997 Wiley-Liss, Inc.     

Novel ring chromosome composed of X- and Y-derived material in a girl with manifestations of Ullrich-Turner syndrome

We present a female infant who has a novel genetic variant of Ullrich-Turner syndrome. Chromosome analysis on amniotic fluid cells obtained because of ultrasound observation of nuchal thickening showed 45,X in all cells. The infant was born with a low posterior hairline and moderate edema over hands and feet. Postnatal chromosome analysis demonstrated two cell lines-47% of the metaphases were 45,X, but 53% had a ring chromosome in addition to the normal X. FISH studies using alpha satellite probes, an X-whole-chromosome-paint (WCP) probe, and a Y-cocktail probe determined that the ring was composed of both X and Y sequences. FISH studies also determined that the KAL locus was present on the ring, but that XIST was absent. PCR-based analysis of lymphocyte DNA documented that the ring contained sequences from both the short and the long arm of the Y chromosome. X-chromosome analysis using a panel of highly polymorphic markers indicated that the ring contained material derived only from Xp22.1 to Xp21.3. No Xq material was identified on the ring, and androgen receptor-based X-inactivation studies suggested that the intact X chromosome was not subject to random X inactivation.     

Supernumerary marker chromosomes (SMCs) in Turner syndrome are mostly derived from the Y chromosome

DNA and FISH (fluorescence in situ hybridization) analysis were carried out in 12 patients with stigmata of Turner syndrome to determine whether the Supernumerary M arker C hromosome (SMC) found cytogenetically in each of these patients was derived from the Y chromosome. The presence of a Y chromosome in these patients may predispose them to develop gonadoblastoma. PCR-Southern blot analysis, followed by FISH, was used to detect the presence of Y chromosome material. The S ex determining R egion Y (SRY), T estis S pecific P rotein Y -encoded (TSPY) and Y -chromosome R NA R ecognition M otif (YRRM) genes, which map at Yp11.31, Yp11.1–11.2 and Yp11.2/Yq11.21–11.23, respectively, were selected as markers, because they span the whole Y chromosome, and more importantly, they are considered to be involved in the development of gonadoblastoma. It was shown that in 12 patients, all of whom had an SMC, the SMC of 11 was derived from the Y chromosome. Furthermore, the presence of the SRY, TSPY and YRRM gene sequences was determined and FISH analysis confirmed the Y origin of the SMCs. The methodology described in this report is a rapid, reliable and sensitive approach which may be easily applied to determine the Y origin of an SMC carried in Turner syndrome. The identification of an SMC is important for the clinical management and prognostic counseling of these patients with Turner syndrome.     

Analysis of sex chromosome aneuploidy in 41 patients with Turner syndrome: a study of 'hidden' mosaicism

We performed a genetic study of sex chromosome mosaicism in 41 Turner syndrome patients. The investigation was carried out in four phases: cytogenetics (G-banding), FISH, PCR for SRY in all 41 cases, and sequencing of the SRY gene in the 2 patients with the Y chromosome. The application of classical alpha-satellite probes (CEP-X and CEP-Y), painting probes (WCP-X and WCP-Y) and also XIST, DXZ4 and two subchromosomal painting libraries (SCPL 116 and SCPL102) covering the short and the long arm of the X chromosome, respectively, allowed us to find new mosaic cell lines (mosaicism) in 37 out of 41 patients; only 4 patients were defined as 45,X non-mosaic. The most frequent hidden mosaic was 45,X/46,XX in 32% of the cases; the presence of isochromosomes comprised 25% and markers 5%. The patients who had been previously diagnosed as mosaics displayed a higher complexity in their karyotypes due to the presence of new cell lines. The Y chromosome and the SRY gene were present in blood and ovarian tissue in 2 patients with karyotypes 45,X/46,XY and 45,X/46,X,idic(Ynf). In both patients, the sequencing of the SRY gene confirmed a nucleotide sequence identical to that of a control male. Our results support the hypothesis of 'the necessity of mosaicism for survival', and thus, a mitotic origin for this syndrome.     

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. Am. J. Med. Genet. 91:377–382, 2000. © 2000 Wiley‐Liss, Inc.     

Two male patients with ring Y: definition of an interval in Yq contributing to Turner syndrome

Turner syndrome is thought to result from the haploinsufficiency of genes on the sex chromosomes, but these genes have not been identified yet. We describe two males with deleted ring Y chromosomes, one (TS) with full Turner syndrome and one (DM) without. TS has short stature, skeletal anomalies, lymphogenic obstruction, cardiovascular abnormalities, and miscellaneous features including pigmented naevi, antimongoloid slanting of the palpebral fissures, and widely spaced nipples. In contrast, DM has short stature but no other specific Turner stigmata except high arched palate and a few pigmented naevi. Since little chromosomal mosaicism was detected, the different segments of the Y chromosome retained by these two males identify the location of one or more "anti-Turner" genes. Most of the Yp pseudoautosomal region and Yq were deleted from both patients during the formation of the ring chromosome, while the Y specific portion of Yp and the centromere were retained. The major difference detected was an interval of proximal Yq present in DM and deleted in TS. None of the previously identified genes, DFFRY, DBY, UTY, or TB4Y, lies entirely within this interval, although DFFRY was truncated by DM's breakpoint. These data suggest that one or more additional "anti-Turner" gene(s) remains to be identified in the region of Yq proximal to DFFRY.     

Two fertile Turner women in a family

Two fertile women, mother and daughter, both presenting sex chromosomal mosaicism (45,X/46,XX/47,XXX and 45,X/46,Xr(X] are reported. The mechanisms through which a Turner women can eventually be fertile are discussed.     

Usefulness of imprint cytology of gonadoblastoma with dysgerminoma in a patient with Turner syndrome and a Y chromosome: A case report and literature review

Ovarian gonadoblastoma coexisting with a dysgerminoma is extremely rare in patients with Turner syndrome (TS) and a Y chromosome. The cytological findings, including imprint cytology, of these unusual ovarian tumors have rarely been reported. We report a rare patient with a gonadoblastoma with dysgerminoma, 3.0 × 2.0 cm in size; she was a 19‐year‐old woman with TS and a Y chromosome. She underwent laparoscopic bilateral gonadectomy, and the tumor was classified as stage IA (pT1aNxM0) according to the International Federation of Gynecology and Obstetrics classification system. Intraoperative imprint cytology revealed two types of neoplastic cells: small tumor cells surrounding light green‐stained or eosinophilic hyaline globules with marked calcification, suspicious for gonadoblastoma; and large, round, atypical cells with abundant cytoplasm, macronucleoli, and marked lymphocytic infiltration (two‐cell pattern), suspicious for dysgerminoma. The cytology results in our patient may represent the second reported results of imprint cytology describing a gonadoblastoma with dysgerminoma. They are the first reported results in a patient with TS and a Y chromosome.     

A molecular and FISH analysis of structurally abnormal Y chromosomes in patients with Turner syndrome

Fourteen patients with Turner syndrome and a structurally abnormal Y chromosome were analysed by PCR amplification and fluorescence in situ hybridisation for the presence of sequences specific to defined regions of the Y chromosome. Thirteen patients had a mosaic karyotype including a 45,X cell line and one case was non-mosaic in cultured lymphocytes. Ten patients had a pseudodicentric Yp chromosome, two an isodicentric Yq, one a pseudodicentric Yq, and one a derived Y chromosome. Two of the patients with a psu dic(Yp) chromosome had complex karyotypes with more than two cell lines, one of which exhibited five morphologically distinct mar(Y) chromosomes, presumably derived from a progenitor psu dic(Yp). Nine of the ten psu dic(Yp) chromosomes were positive for all Yp and Yq probes used except DYZ1 which maps to Yq12, suggesting a common breakpoint near the Yq euchromatin/heterochromatin boundary. In the three patients with a dicentric Yq chromosome two different breakpoints were observed; in two it was between PABY and the subtelomeric repeat sequence and in one it was between DYZ5 and AMGY in proximal Yp. Our results suggest that the great majority of structurally abnormal Y chromosomes found in Turner syndrome mosaics contain two copies of virtually all of the functional Y chromosome euchromatin.