Turner综合征患者标记染色体的鉴定与分析

目的 分析11例携带标记染色体的Turner综合征患者的核型,研究这类染色体的表型效应。方法 选择11例具Turner综合征表型的患者,常规核型分析均显示为携带标记染色体的嵌合体,其中6例标记染色体呈环状。患者G带核型表示为mos．45,X／46,X,＋mar或者mos．45,X／46,X,＋r．以X／Y着丝粒探针,应用荧光原位杂交（FISH）技术分析这些标记染色体起源,对其中2例较大的环状染色体,结合反向染色体涂染确定断裂位点,比较不同断裂位点的标记染色体的遗传学效应。结果11例患者所携带的标记染色体均为环状染色体,r（X）的断裂位点分别位于Xp22、Xq22、Xq24、Xq26等。结论 Turner综合征患者的标记染色体主要来源于X染色体,且表现为r（X）形式。r（X）均以嵌合型的形式存在。     

Laparoscopic gonadectomy in a case of a dicentric fluorescent Y-chromosome mosaicism with Turner-like phenotype and virilized external genitalia

In few cases of Turner syndrome the karyotype reveals the presence of an additional Y-bearing cell line, which is referred to as a borderline case of mixed gonadal dysgenesis. We report a 20-year-old woman with primary amenorrhea, virilization and a few Turner stigmata, who revealed rare mosaicism of 45,X/46,X dic (Y; 5)(q12; q11), +5/46,X, der (Y), which was detected by conventional G-banding and multicolor spectral karyotyping. She underwent laparoscopic gonadectomy in which mixed gonadal dysgenesis was found and both gonads were removed. No evidence of gonadoblastoma was noted on the gonads. Virilization improved postoperatively. We recommend gonadectomy via laparoscope in women presenting with Turner-like phenotype, virilization and the presence of a Y chromosome. This report describes the role of cytogenetic and molecular genetic investigations in the definition of mosaicism in Turner syndrome.     

Y chromosome mosaicism and occurrence of gonadoblastoma in cases of Turner syndrome and amenorrhoea

In the present study, 73 cases with a clinical diagnosis of Turner syndrome, or with primary or secondary amenorrhoea without frank Turner phenotype, were evaluated for presence of low level Y chromosome mosaicism using molecular methods. Fluorescence in-situ hybridization for centromere and q arm of the Y chromosome and nested polymerase chain reaction for the sex determining region on Y (SRY) gene were performed in peripheral blood, buccal cells and gonadal biopsies. The overall frequency of Y chromosome mosaicism was found to be 18% (13/73 cases). Four cases (16%) of Turner syndrome had Y chromosome mosaicism, seven cases (28%) with primary amenorrhoea and two cases (9%) with secondary amenorrhoea had Y chromosome mosaicism. Histologically detectable gonadoblastoma was observed in one of seven cases (14%) that had Y chromosome mosaicism. This frequency is lower than that reported previously, underscoring the need for large prospective investigations to determine the frequency of Y chromosome mosaicism and occurrence of gonadoblastoma in cases of Turner syndrome and other forms of amenorrhoea.     

Screening of seven putative 45,X subjects with deoxyribonucleic acid probes to detect low-level mosaicism for Y cell lines

The frequency of monosomy X in cytogenetically abnormal abortion material (10% to 15%) suggests that viable 45,X subjects might have covert mosaicism for X or Y cell lines. The deoxyribonucleic acid samples from seven 45,X subjects with Turner syndrome were examined with three Y-specific deoxyribonucleic acid probes. Successive hybridizations with each of these three sensitive deoxyribonucleic acid probes did not reveal any Y-specific band.     

Mucinous cystadenoma in a female patient with 45,X/46,XY karyotype

The mosaic karyotype of 45,X/46,XY has a wide phenotypic spectrum and there are substantial differences between prenatally and postnatally diagnosed cases. The phenotype varies between normal male to classical Turner syndrome. There is a high risk of gonadal tumor development in the dysgenetic gonads of patients with sex chromosome mosaicism. We report a case of a 24-year-old patient with a pelvic mass and amenorrhea referred to our laboratory for karyotyping. Peripheral blood chromosome analysis showed a mosaic karyotype of 45,X[17]/46,XY[83]. The tumor originated from the left ovary and the right ovary was found to be a streak gonad. The uterus was intact. Pathologic examination of the tumor revealed mucinous cystadenoma. Physical examination of the patient showed signs of Turner syndrome, as short stature (145 cm), short neck and asymmetric shoulders. Her mental state was normal. Y chromosome microdeletion screening involving SRY and ZFY genes was performed and no deletion was found. The patient was informed about the condition during the genetic counseling session.     

Prenatal diagnosis of 45,X and 45,X mosaicism: the need for thorough cytogenetic and clinical evaluations

OBJECTIVES: Mosaicism involving a 45,X cell line is relatively common in prenatal diagnosis. In prenatally diagnosed cases, the prognosis of non-mosaic 45,X and 45,X/46,XY mosaicism are different. Therefore, accurate identification of a cell line containing Y chromosome is critical for genetic counseling and postnatal management. METHODS: We investigated the ultrasound findings and outcomes of pregnancies with a 45,X cell line identified during mid-trimester cytogenetic analysis. RESULTS: A total of 105 cases were found to have a 45,X cell line by standard cytogenetic analysis. Seventy-four cases were found to have non-mosaic 45,X at initial diagnosis. Of these 74 cases, 68 had abnormal ultrasound findings that were characteristic of Turner syndrome. Of the six cases with normal ultrasound findings, ultrasound examination was normal with male genitalia identified in three cases. Thorough cytogenetic and fluorescent in situ hybridization (FISH) analysis identified Y chromosome material in all three cases, one with a dicentric Y;14 chromosome and the other two cases with a marker chromosome containing Sex-determining Region (SRY) material in a small portion of the cells. In contrast, in 31 cases with a mosaic 45,X karyotype, ultrasound abnormality was identified only in one case. CONCLUSIONS: The present data suggest the need for follow-up ultrasound examination and thorough cytogenetic and molecular analysis for Y chromosome material in 45,X cases with normal ultrasound findings.     

Maternal XX/X chromosome mosaicism in donor oocyte in vitro fertilization (IVF)

ObjectiveTo evaluate if the degree of maternal X chromosome mosaicism is correlated to the pregnancy loss rate in donor oocyte IVF in women with a Turner syndrome mosaic (TS-Mosaic) diagnosis.DesignProspective trial.Patients and methodsWomen with X chromosome Turner syndrome mosaicism and infertility were enrolled in a clinical trial. The rate of mosaicism was determined through florescence in situ hybridization (FISH) of 500 maternal lymphocytes. Following a detailed medical, including cardiac, evaluation, donor oocyte in vitro fertilization (IFV) was performed and pregnancy and pregnancy loss rates were observed.ResultsThe rates of maternal X chromosome mosaicism noted in the cycles from women with miscarriages (3%, 4%, 4%, and 6%) were not statistically different from cycles in TS-Mosaic women with normal deliveries (3% and 11%). These data suggest that the rate of maternal X chromosome mosaicism does not affect pregnancy loss rates in TS-Mosaic women undergoing donor oocyte IVF.     

Reproductive outcomes after preimplantation genetic testing in mosaic Turner syndrome: a retrospective cohort study of 100 cycles

PurposeThe purpose of this study is to explore the reproductive outcomes of women with Turner syndrome (TS) in preimplantation genetic testing (PGT) cycles.MethodsA retrospective study of 100 controlled ovarian stimulating cycles, 68 TS (sixty-four mosaic Turner syndrome (MTS) and four pure Turner syndrome (PTS)) women underwent PGT was conducted from 2013 to 2018.ResultsEmbryo X chromosome abnormal rates of TS women were significantly higher than women with normal karyotype (7.04 vs 1.61%, P<0.01). Cumulative live birth rates (CLBR) after PGT-NGS treatment were lower in TS than control (31.15 vs 45.59%, P<0.05). Clinical pregnancy rates per transfer (CPR), miscarriage rates (MR) and live birth rates per transfer (LBR) remained comparable between TS and control group. Reproductive outcomes (X chromosome abnormal rates, CPR, MR, LBR and CLBR) among low (<10%), medium (10–50%) and high (>50%) level 45,X mosaicism groups were not statistically different.ConclusionsTo avoid high risk of embryo X chromosome abnormalities, prenatal or preimplantation genetic testing should be recommended to mosaic or pure TS patients.     

Prenatal diagnosis of a small supernumerary,XIST-negative,mosaic ring X chromosome identified by fluorescence in situ hybridization in an abnormal male fetus

Marker or ring X [r(X)] chromosomes of varying size are often found in patients with Turner syndrome. Patients with very small r(X) chromosomes that did not include the X-inactivation locus (XIST) have been described with a more severe phenotype. Small r(X) chromosomes are rare in males and there are only five previous reports of such cases. We report the identification of a small supernumerary X chromosome in an abnormal male fetus. Cytogenetic analysis from chorionic villus sampling was performed because of fetal nuchal translucency thickness and it showed mosaicism 46,XY/47,XY,+r(X)/48,XY,+r(X),+r(X). Fluorescence in situ hybridizations (FISH) showed the marker to be of X-chromosome origin and not to contain the XIST locus. Additional specific probes showed that the r(X) included a euchromatic region in proximal Xq. At 20 weeks gestation, a second ultrasound examination revealed cerebral abnormalities. After genetic counselling, the pregnancy was terminated. The fetus we describe is the first male with a mosaic XIST-negative r(X) chromosome identified at prenatal diagnosis. The phenotype we observed was probably the result of functional disomy of the genes in the r(X) chromosome, secondary to loss of the XIST locus.     

Pregnancy rate and outcome in Swedish women with Turner syndrome

Pregnancies occurred in 57 (12%) of 482 Swedish women with Turner syndrome with a liveborn rate of 54% in 124 pregnancies. Spontaneous pregnancies occurred in 40%, mainly in women with 45,X/46,XX mosaicism, and oocyte donation in 53% where miscarriages were less frequent, odds ratio = 0.43 (95% confidence interval 0.17-1.04).     

Low-level X chromosome mosaicism in women with sporadic premature ovarian failure

Low-level X chromosome mosaicism and its clinical relevance are still under debate. It could be interpreted as a technical artefact, genuine mosaicism or as being age-related. This study evaluated the contribution of X chromosome mosaicism in phenotypically normal women with sporadic premature ovarian failure (POF). During 1999-2008, 114 patients with POF and 64 age matched controls were karyotyped. Thirteen patients (11.4%) had true X chromosome mosaicism (>10% of aneuploid cells) and 12 had (10.5%) low-level X-mosaicism (between 6-10% of aneuploid cells). The mean age of women with true and low-level mosaicism was 26.0 ± 5.65 years and 35.92 ± 3.87 years, respectively (P < 0.001). In the control group the incidence of cells with an abnormal number of X chromosomes was 1-3%. The results have practical implications for genetic counselling and fertility treatment. To search and confirm the low-level mosaicism, a higher number of metaphases should be analysed or additional fluorescence in-situ hybridization analysis must be performed. Although peripheral blood does not reflect the situation in ovarian tissue well, it is presumed that there are different aetiological causes for true and low-level X chromosome mosaicism. The possible causes and reproductive significance of low-level X chromosome mosaicism are discussed.     

A Spontaneous Pregnancy in a Patient with Turner Syndrome with 45,X/47,XXX Mosaicism: A Case Report and Review of the Literature

Background

Turner syndrome is a chromosomal abnormality, due to a total or partial loss of 1 of the X chromosomes and is mostly characterized clinically by short stature and primary ovarian insufficiency. Spontaneous pregnancies are rare (5%) and of relatively high risk. This is 1 of few reported cases of spontaneous conception and favorable prognosis in a patient with Turner syndrome and a 45,X/47,XXX karyotype.

Mosaic 45,X/46, XX at amniocentesis with high-level mosaicism for 45,X in a pregnancy with a favorable fetal outcome and postnatal decrease of the 45,X cell line

ObjectiveWe present mosaic 45,X/46, XX at amniocentesis with high-level mosaicism for 45,X in a pregnancy with a favorable fetal outcome and postnatal decrease of the 45,X cell line.Case reportA 20-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation because of the non-invasive prenatal testing (NIPT) result of −4.82 Z score in sex chromosome at 12 weeks of gestation suggestive of Turner syndrome in the fetus. Amniocentesis revealed a karyotype of 45,X [18]/46,XX [15], and simultaneous multiplex ligation-dependent probe amplification (MLPA) on the DNA extracted from uncultured amniocytes showed mosaic Turner syndrome. Prenatal ultrasound and parental karyotypes were normal. She was referred for genetic counseling at 24 weeks of gestation, and continuing pregnancy was encouraged. At 39 weeks of gestation, a 2550-g phenotypically normal female baby was delivered. The karyotypes of cord blood, umbilical cord and placenta were 45,X [24]/46,XX [16], 45,X [23]/46,XX [17] and 45,X [28]/46,X,del(X) (q23)[12], respectively. When follow-up at age two months, the neonate was phenotypically normal in development. The peripheral blood had a karyotypes of 45,X [16]/46,XX [24]. Interphase fluorescence in situ hybridization (FISH) analysis on 103 buccal mucosal cells showed normal disomy X signals in all cells.ConclusionHigh-level mosaicism for 45,X in 45,X/46, XX at amniocentesis can be associated with a favorable fetal outcome, cytogenetic discrepancy in various tissues, and postnatal decrease of the 45,X cell line.     

Molecular delineation of de novo small supernumerary marker chromosomes in prenatal diagnosis,a retrospective study

ObjectivesTo define the genotype-phenotype correlation of small supernumerary marker chromosomes (sSMCs) and conduct precise genetic counseling, we retrospectively searched and reviewed de novo sSMCs cases detected during prenatal diagnosis at The First Affiliated Hospital of Zhengzhou University.Materials and methodsChromosome karyotypes of 20,314 cases of amniotic fluid from pregnant women were performed. For 16 samples with de novo sSMCs, 10 were subjected to single-nucleotide polymorphism (SNP) array or low-coverage massively parallel copy number variation sequencing (CNV-seq) analysis.ResultsAmong the 10 sSMCs cases, two sSMCs derived from chromosome 9, and three sSMCs derived from chromosomes 12, 18 and 22. The remaining 5 cases were not identified by SNP array or CNV-seq because they lacked euchromatin or had a low proportion of mosaicism. Four of them with a karyotype of 47,XN,+mar presented normal molecular cytogenetic results (seq[hg19] 46,XN), and the remaining patient with a karyotype of 46,XN,+mar presented with Turner syndrome (seq[hg19] 45,X). Five sSMCs samples were mosaics of all 16 cases.ConclusionConsidering the variable origins of sSMCs, further genetic testing of sSMCs should be performed by SNP array or CNV-seq. Detailed molecular characterization would allow precise genetic counseling for prenatal diagnosis.     

Dysgerminoma in a 10-Year Old with 45X/46XY Turner Syndrome Mosaicism

BackgroundTurner syndrome is a genetic disorder resulting from the absence of or structural abnormality of one X chromosome. The presence of Y chromosome material in girls with Turner syndrome confers an increased risk of benign and malignant germ cell tumor and prophylactic bilateral gonadectomy is recommended.CaseA 10-year-old Turner mosaic syndrome (45X/46XY) patient underwent prophylactic gonadectomy after unremarkable preoperative pelvic imaging. Histopathology showed a streak right gonad, and left gonad with gonadoblastoma with limited degree of infiltrating germinoma.Summaryand ConclusionGonadoblastoma and dysgerminoma have been reported in girls with Turner mosaic who carry Y chromosome material. Prophylactic gonadectomy should be considered in these girls without delay.     

Evaluation of sex chromosome aneuploidies in women with Turner's syndrome by G-banding and FISH. A serial case study

OBJECTIVE: To evaluate sex chromosome aneuploidies in patients with Turner's syndrome using two cytogenetic techniques. STUDY DESIGN: A sample of 35 women with a clinical suspicion of Turner syndrome was examined in the Hospital of Obstetrics and Gynecology, Instituto Mexicano del Seguro Social, Monterrey, Mexico. They were subjected to a conventional cytogenetic technique with G-banding and to fluorescence in situ hybridization (FISH) using a specific alpha satellite X chromosome (DXZ1) and specific alpha satellite Y chromosome (DYZ1). RESULTS: Using both techniques, 17 cases (48.57%) showed the same karyotype. Using FISH: (1) in 8 cases the presence of the Y chromosome was confirmed, (2) in 18 cases (51.43%) a new cell line was identified, (3) in 2 cases (5.71%) the derivative X was clarified, and (4) in 3 cases (8.57%) the origin of the chromosome markers (1 of X chromosome and 2 of Y chromosome) was delineated. FISH highlighted the differences between the initial diagnosis, based on G-banding, and the final diagnosis, determined by specific probes for the X and Y chromosomes. CONCLUSION: FISH is a useful tool in the detection of low-frequency cell lines and identification of the nature and origin of derivative chromosomes and unknown chromosome markers that have important implications for the treatment of patients with Turner's syndrome.     

Application of QF-PCR for the prenatal assessment of discordant monozygotic twins for fetal sex

OBJECTIVE: To establish the utility of quantitative fluorescent polymerase chain reaction (QF-PCR) in order to determine the zygosity of multiple pregnancies, as well as to define the origin of the most frequent aneuploidies in amniotic fluid samples. METHODS: We describe the case of a monochorionic (MC) diamniotic (DA) pregnancy with phenotypically discordant twins (nuchal cystic hygroma and non-immune hydrops in twin A and no anomalies in twin B). QF-PCR was performed for rapid prenatal diagnosis in uncultured amniocytes and subsequently in cultured cells. Polymorphic markers for chromosomes X, Y, 13, 18 and 21 were used for determination of zygosity as well as sex chromosome aneuploidy. RESULTS: Twin A showed a Turner Syndrome (TS) mosaicism pattern by QF-PCR in uncultured amniocytes. The monozygotic origin of the pregnancy was determined. Interphase fluorescence in situ hybridization (I-FISH) in this sample showed a mosaicism X0/XY (83/17%). Cytogenetic analysis revealed a 45,X0 karyotype in twin A and a 46,XY karyotype in twin B. CONCLUSIONS: QF-PCR is a reliable tool for the determination of the zygosity independently of the chorionicity and the fetal sex in case of twin pregnancy. Testing both direct and cultured cells can provide useful results for genetic counselling in chromosomal mosaicisms.     

Gonadal dysgenesis in own material]

Eleven patients with Turner syndrome and 6 with pure gonadal dysgenesis were examined. Diagnosis was made on the base of clinical and cytogenetic examination. All patients had primary amenorrhea and underdevelopment of primary, secondary and tertiary sexual features. Hormonal estimations revealed elevated FSH serum concentration in women with Turner syndrome and with pure gonadal dysgenesis (46, XY) vs. to patients with 46, XX. Estradiol and Progesterone levels were low in all cases. All women were treated with estrogens and progestational agents in sequential manner with good results. We did not observe significant phenotypic differences between patients with monosomie X and patients with structural abnormalities within chromosome X and mosaicism.