Gonadoblastoma in Turner syndrome patients with nonmosaic 45,X karyotype and Y chromosome sequences

Yolk Sac Tumor of the Ovary in Mosaic 46XX Turner Syndrome

Introduction

Correlation of Turner syndrome (TS) with germ cell malignancy is acknowledge in TS patient with Y chromosome material but not otherwise. This case report wishes to highlight yolk sac tumor occurrence in patients with TS 46XX karyotype mosaicism.

Case Report

A 23-year-old nulligravid woman was admitted with abdominal mass and vaginal bleeding. She had primary amenorrhea and had already been diagnosed with TS. Her karyotype was 46XX with 5% X mosaicism. Ultrasonography revealed a solid mass measuring 14.05 x 10.99 cm based on the International Ovarian Tumor Analysis (IOTA) simple rule, M1 and M2. During surgery, a solid mass originates from her left ovary measuring 20 x 15 x 15 cm with adhesion to omentum, ileum, and caecum was found. Pathology examination reveals it's an endodermal sinus tumors (EST).

Discussion

TS with Y cells are closely linked with germ cell malignancy but not otherwise. It's still unclear what causes the malignancy in such cases.

Conclusion

The present report illustrates a rare case of EST occurred in a TS patient with 46XX mosaicism.

Turner Syndrome Mosaicism 45,X/46,XY with Genital Ambiguity and Duchenne Muscular Dystrophy: Translational Approach of a Rare Italian Case

Turner syndrome (gonadal dysgenesis with short stature and sterility) is characterized by chromosomal karyotype 45,X in 50% of cases or by mosaicism (45,X/46,XX and 45,X/46,XY) in 30-40% or X structural defects (deletions, long arm isochromosome, ring chromosome). When mosaic Turner syndrome (TS) occurs with a Y chromosome, there may be ambiguous genitalia. Duchenne muscular dystrophy (DMD) is an inherited neuromuscular disease with an X-Linked recessive pattern of inheritance that predominantly affects males, while females are usually asymptomatic. DMD has also been observed in groups of females affected by TS, not homozygous for the mutation. Here, we report a case of an Indian neonate born with ambiguous genitalia diagnosed prenatally by ultrasound who had a karyotype of 45,X/46,XY and who also had Duchenne muscular dystrophy caused by a de novo mutation in the DMD gene. Physical examination was normal without the typical dysmorphic features of TS with the exception of the genitourinary system showing ambiguous genitalia. Gender was assigned as female. At the age of three years, she had increasing difficulty walking, running, jumping and climbing stairs, proximal upper and lower extremity muscle weakness and a positive Gowers' sign. In addition, the serum creatine kinase (CK) value was over 30X the upper limit of normal. This study shows that DMD can occur in females with TS having 45,X/46,XY mosaicism and that this coexistence should be considered in women affected by TS who start to develop potential typical symptoms such as motor or developmental delay.

Recognition of the Y chromosome in Turner syndrome using peripheral blood or oral mucosa tissue

PURPOSE

Turner syndrome is defined as total or partial loss of the second sex chromosome in a phenotypically female patient. Due to the possibility of hidden mosaicism of fragments of the Y chromosome and development of gonadoblastoma, we evaluated the presence of such fragments in 2 tissues with different embryonic origins, peripheral blood lymphocytes (mesoderm), and oral mucosal cells (ectoderm) using multiplex polymerase chain reaction.

METHODS

DNA samples were collected from 109 patients, and primers for the SRY, TSPY, and AMELX genes were used.

RESULTS

We found 14 patients (12.8%) with positive molecular markers for the Y chromosome. The study of tissues of different embryological origin showed the same degree of agreement, sensitivity, and specificity.

CONCLUSION

Oral mucosa cells have a simpler method of collection that is less invasive and requires less time for DNA extraction at a lower cost.

Y Chromosome Material in Turner Syndrome

Background Turner Syndrome (TS) is a frequently identified chromosomal disease in humans characterized by short stature, sexual infantilism, streak gonads, primary amenorrhea, and a number of somatic anomalies. Approximately 55% of TS individuals have a nonmosaic 45,X karyotype. In addition, a cell line with a Y chromosome is present in 5% of patients, which is undetectable by the standard cytogenetic analysis. The identification of Y chromatin in some TS individuals has been associated with the development of gonadoblastoma. Therefore, it is important to exclude the presence of Y chromatin in TS individuals. In this study, it was planned to detect cases with mosaicism in terms of Y chromatin with the help of Y whole chromosome probes (WCP) from individuals with TS by fluorescence in situ hybridization (FISH) analysis. Methodology Forty-four patients with Turner syndrome, who were being followed up in the Genetics Unit, were contacted and invited for the study. Of the 44 invited patients, 28 responded to the invitation. In this study, it was planned to detect TS patients with mosaicism in terms of Y chromatin with the help of the Y whole chromosome probe. Results The majority of the cases (71.42%) included in the study carried pure X monosomy, which is the classical Turner syndrome karyotype. Other structural X chromosome aberrations, in isolated or mosaic forms, were less frequently represented. Y chromosome sequences were searched in 28 cases with Turner syndrome by the FISH method using Y whole chromosome probe. Y chromosome sequence was detected in one (3.5%) case of 28 cases. Conclusions It is recommended that individuals with Turner syndrome be screened for Y chromatin. Detection of this will provide information and guidance to individuals with Turner syndrome, especially in terms of the risk of developing gonadoblastoma, with advanced clinical consultation. This study was conducted to emphasize the importance of this.

Mosaic Turner Syndrome With 45,X/46,XY Mosaicism and Apparent Absent Uterus

Turner syndrome (TS) is a relatively common chromosomal abnormality in females. Short stature, gonadal dysgenesis, and somatic dysmorphic features are the characteristic features of the syndrome. The chromosomal abnormalities of TS are highly variable; 45,X/46,XY mosaicism accounts for 10-12% of cases of Turner syndrome. Despite the presence of hypogonadism, affected females typically have a uterus. Here, we report the case of a 22-year-old female who presented at 15 years of age with primary amenorrhea. She was diagnosed with Turner syndrome mosaicism with a karyotype of 45,X/46,XY. Her pelvic imaging showed an absent uterus and ovaries. Due to the presence of a Y chromosome, she underwent prophylactic gonadectomy. Histopathology of her removed gonads confirmed the diagnosis of mixed gonadal disorder. She was started on estrogen replacement. Four years after treatment, she developed her menses. Her repeated pelvic magnetic resonance imaging showed the presence of a small uterus.

[Etiology and genetic diagnosis of short stature in children]

OBJECTIVE

To study the etiology and genetic diagnosis of children with short stature.

METHODS

A retrospective analysis was performed to study the etiological distribution and clinical features of 86 children with short stature.

RESULTS

A total of 6 causes were observed in these children, among which idiopathic short stature (ISS, 41%) and growth hormone deficiency (GHD, 29%) were the most common causes, followed by genetic diseases (14%). There were no significant differences in age at the time of diagnosis, body height, body length and weight at birth, body height of parents and insulin-like growth factor-1 levels between the genetic disease group and the ISS/GHD groups (P>0.05). Compared with the ISS group, the genetic disease group had significantly lower deviation from the 3rd percentile for the height of children of the same age and sex (ΔP3) and height standard deviation score (P<0.05), while there were no significant differences between the genetic disease and GHD groups (P>0.05). The analysis of the clinical manifestations for the genetic disease group showed heterogeneity and phenotypic overlap in children with different genetic diseases.

CONCLUSIONS

ISS, GHD and genetic diseases are major causes of short stature in children. For children with severe short stature, genetic testing should be performed to make a definitive diagnosis after GHD has been excluded.

Inherited Deletion of 1q, Hyperparathyroidism and Signs of Y-chromosomal Influence in a Patient with Turner Syndrome

We report a detailed phenotypic, cytogenetic and molecular characterization of a patient prenatally diagnosed with Turner syndrome (TS). In addition to having typical TS clinical characteristics including webbed neck, high arched palate and coarctation of the aorta, the patient had features less frequently seen in TS. These included recurrent parathyroid adenomas, growth along the 75^th-90^th centiles on the TS height curve despite minimal treatment with growth hormone, behavioral problems and evidence of gonadal dysgenesis with testicular-like structures, such as seminiferous tubules lined by Sertoli cells and a contiguous nodule of Leydig cells. While fluorescence in situ hybridization (FISH) failed to detect Y-chromosome material in gonadal tissue or blood samples, chromosomal microarray analysis (CMA) confirmed X monosomy and a 4.69 Mb copy number loss on 1q31.2q31.3 (bp 192,715,814 to 197,401,180). This region contains the CDC73 gene which has been associated with hyperparathyroidism-jaw tumor syndrome, features of which include recurrent, functional parathyroid adenomas and behavioral issues. This case illustrates how atypical features in a TS patient, such as robust growth and recurrent parathyroid adenomas, may suggest an underlying molecular etiology that should be explored by additional genetic diagnostic modalities. It is therefore appropriate in such cases to conduct further genetic testing, such as CMA and FISH, to explore other diagnostic possibilities and possibly prevent further complications.

Detection of the SRY gene in patients with Turner Syndrome

BACKGROUND

If turner syndrome (TS) patients have a Y-containing cell line, they have an increased risk for gonadal tumors. TS patients are therefore screened for Y-chromosome and Y-specific sequences, such as SRY, DYZ1, DYZ3, DYS132, ZFY, TSPY, etc. In addition, since the dysgenetic gonad may include the stroma and granulosa/sertoli cells, which produce androgens, virilization can seen in girls with Y-chromosomal material. Prophylactic gonadectomy may therefore be required for optimal management in such patients. Our aim is to discuss our observations in the follow-up of TS patients.

METHODS

SRY was investigated in 71 out of 85 TS cases (aged 3 months-27 years) between 2005 and 2017. Fluorescent in situ hybridization (FISH) was used until 2014, after which SRY analysis was performed using the polymerase chain reaction (PCR) method. SRY analysis was performed a second time using PCR in 25 cases previously investigated with FISH.

RESULTS

We identified no positive cases. No pathological findings in terms of virilization, clitoromegaly, or posterior labial adhesions were also determined in our TS cases. Further studies were not required since no pathological findings also were detected at ultrasonography.

CONCLUSION

If Y-chromosome material has not been detected by conventional cytogenetic methods in TS patients with masculine features, further techniques should be applied to prevent the risk of invasive tumors, such as multiple sequences beside the Y centromere. This approach will prevent overtreatment.

Mixed gonadal dysgenesis in 45,X Turner syndrome with SRY gene

Turner syndrome is the most common chromosomal disorder in girls. Various phenotypic features show depending upon karyotype from normal female through ambiguous genitalia to male. Usually, Turner girls containing 45,X/46,XY mosaicism, or sex-determining region Y (SRY) gene may have mixed gonadal dysgenesis with various external sexual differentiation. We experienced a short statured 45,X Turner girl with normal external genitalia. Because SRY gene was positive, laparoscopic gonadectomy was performed. The dysgenetic gonads revealed bilateral ovotesticular tissues. The authors report a mixed gonadal dysgenesis case found in clinical 45,X Turner patient with positive SRY gene. Screening for SRY gene should be done even the karyotype is 45,X monosomy and external genitalia is normal.

[Prevalence of Y-chromosome sequences and gonadoblastoma in Turner syndrome]

OBJECTIVE

To assess the prevalence of Y-chromosome sequences and gonadoblastoma in patients with Turner syndrome using molecular techniques.

DATA SOURCE

A literature search was performed in Pubmed, limiting the period of time to the years 2005 to 2014 and using the descriptors: Turner syndrome and Y sequences (n=26), and Turner syndrome and Y-chromosome material (n=27). The inclusion criteria were: articles directly related to the subject and published in English or Portuguese. Articles which did not meet these criteria and review articles were excluded. After applying these criteria, 14 papers were left.

DATA SYNTHESIS

the main results regarding the prevalence of Y-chromosome sequences in Turner syndrome were: 1-about 60% of the studies were conducted by Brazilian researchers; 2-the prevalence varied from 4.6 to 60%; 3-the most frequently investigated genes were SRY, DYZ3 and TSPY; 4-seven studies used only PCR, while in the remaining seven it was associated with FISH. Nine of the 14 studies reported gonadectomy and gonadoblastoma. The highest prevalence of gonadoblastoma (33%) was found in two studies. In five out of the nine papers evaluated the prevalence of gonadoblastoma was 10 to 25%; in two of them it was zero.

CONCLUSIONS

according to these data, molecular analysis to detect Y-chromosome sequences in TS patients is indicated, regardless of their karyotype. In patients who test positive for these sequences, gonadoblastoma needs to be investigated.

Buccal cell FISH and blood PCR-Y detect high rates of X chromosomal mosaicism and Y chromosomal derivatives in patients with Turner syndrome

Turner syndrome (TS) is the result of (partial) X chromosome monosomy. In general, the diagnosis is based on karyotyping of 30 blood lymphocytes. This technique, however, does not rule out tissue mosaicism or low grade mosaicism in the blood. Because of the associated risk of gonadoblastoma, mosaicism is especially important in case this involves a Y chromosome. We investigated different approaches to improve the detection of mosaicisms in 162 adult women with TS (mean age 29.9 ± 10.3). Standard karyotyping identified 75 patients (46.3%) with a non-mosaic monosomy 45,X. Of these 75 patients, 63 underwent additional investigations including FISH on buccal cells with X- and Y-specific probes and PCR-Y on blood. FISH analysis of buccal cells revealed a mosaicism in 19 of the 63 patients (30.2%). In five patients the additional cell lines contained a (derivative) Y chromosome. With sensitive real-time PCR we confirmed the presence of this Y chromosome in blood in three of the five cases. Although Y chromosome material was established in ovarian tissue in two patients, no gonadoblastoma was found. Our results confirm the notion that TS patients with 45,X on conventional karyotyping often have tissue specific mosaicisms, some of which include a Y chromosome. Although further investigations are needed to estimate the risk of gonadoblastoma in patients with Y chromosome material in buccal cells, we conclude that FISH or real-time PCR on buccal cells should be considered in TS patients with 45,X on standard karyotyping.

Molecular detection of cryptic Y-chromosomal material in patients with Turner syndrome

A systematic search for a hidden Y-chromosome mosaicism, in Turner syndrome (TS) patients is justified by the evaluation of the risk of development of germ cell tumors. In this study, we analyzed cryptic Y-chromosome derivatives by polymerase chain reaction (PCR) coupled with fluorescence in situ hybridization (FISH) using Y-specific sequences in patients with TS, and validated this methodology. Unrelated patients with TS (n=32) of Mexican mestizo ethnic origin were diagnosed using cytogenetic analysis. Clinical assessment, endocrine evaluation, karyotyping, FISH and PCR analysis of the Y-chromosomal loci were performed. We found that 9.4% (3 out of 32) patients with TS had Y-chromosome material. Two patients showed Y-chromosome by conventional cytogenetics. One patient had no Y-chromosome by initial karyotyping (45, X) but was positive by lymphocyte PCR DNA analysis of the Y-sequence-specific sex-determining region Y (SRY) gene. Our results suggest that the detection of the Y-chromosome material using sensitive methods, such as PCR coupled with FISH, should be carried out in all patients with TS and should not be limited to TS patients with cytogenetically identifiable Y-chromosome and/or virilization.

Dysgerminoma in a female with turner syndrome and Y chromosome material: A case-based review of literature

We report a 17-year-old girl evaluated for primary amenorrhea. Cytogenetic analysis of the peripheral blood lymphocytes revealed normal autosomes with 46X inv (Y) confirming the diagnosis of Turner's syndrome with Y cell line. Treatment was initiated with conjugated estrogen while recommending bilateral prophylactic oophorectomy to the patient. One year later the patient presented with abdominal mass, biopsy of the specimen following resection confirmed dysgerminoma originating from right ovary with no invasion or metastasis. The literature is reviewed with regard to the various pathogenetic mechanisms proposed for the development of germ cell tumors in ovary, the cytogenetic findings and recommendations to handle such scenario.

Diversity of sex chromosome abnormalities in a cohort of 95 Indonesian patients with monosomy X

BACKGROUND

Monosomy × or 45,X is a cytogenetic characteristic for Turner syndrome. This chromosome anomaly is encountered in around 50% of cases, but wide variations of other anomalies have been found. This report is to describe the cytogenetic characteristics of 45,X individuals. To the best of our knowledge, there were no large series of 45,X cases has been reported from Indonesia.

RESULTS

Ninety five cases with 45,X cell line found, of which 60 were detected by karyotyping, 4 by FISH for sex chromosomes, and 31 by both karyotyping and FISH. Using karyotyping 37 out of 91 cases(40.6%) were identified as 45,X individuals, while cases who underwent FISH only 4 out of 35 cases (11.4%) showed 45,X result, resulting in total of 39 45,X cases (41.1%), and the rest 56 (58.9%) cases are mosaic. Among these cases, 21 out of 95 (22.1%) have Y or part of Y as the second or third sex chromosome in their additional cell lines. Result discrepancies revealed in 22 out of 31 cases who underwent both FISH and karyotyping, of which 7 showed normal 46,XX or 46,XY karyotypes, but by FISH, additional monosomy × cell line was found. Most of the cases were referred at the age of puberty (8-13 years old) or after that (14-18 years old), 31 and 21 cases respectively, and there were 14 cases were sent in adulthood.

CONCLUSION

Wide variations of sex chromosome aberrations have been detected using the combination of conventional cytogenetic and FISH, including detection of low level of mosaicism and Y-chromosome fragments. Result discrepancies using both techniques were found in 22/31 cases, and in order to obtain a more details of sex chromosome constitution of individuals with 45,X cell line both FISH and karyotyping should be carried out simultaneously.

[The inclusion of new techniques of chromosome analysis has improved the cytogenetic profile of Turner syndrome]

OBJECTIVE

To evaluate the effect of the improvement of chromosome analysis on the cytogenetic findings of Turner syndrome (TS) patients.

METHODS

Retrospective study of the results of the karyotypes of 260 patients with TS, regarding banding techniques, number of cells analyzed and results of investigation of Y-chromosome sequences. According to karyotype, divided in 45,X; sex chromosome mosaicism without Y; structural aberrations of sex chromosomes with or without mosaicism; sex chromosome mosaicism with Y.

RESULTS

45,X was the most frequent karyotype (108), followed by structural aberrations (88) and mosaics (58 without Y and 6 with Y). Introduction of banding techniques and increase in the number of cells analyzed resulted in progressive decrease of 45,X karyotype and increase of structural aberrations. The study of Y-chromosome sequences was performed in 96 cases of which 10 resulted positive.

CONCLUSIONS

Improvement of chromosome analysis over the years has modified the cytogenetic profile of TS.

Y-chromosome markers in Turner syndrome: Screening of 130 patients

BACKGROUND

The presence of Y-chromosome material in patients with Turner syndrome (TS) is a risk factor for the development of gonadoblastoma. Cytogenetic analysis detects Y-chromosome mosaicism in about 5% of Turner patients. However, if Y-chromosome sequences are present in only a few cells, they may be missed by routine analysis. The use of molecular techniques to detect the presence of Y-chromosome fragments in such patients is becoming increasingly important.

AIM

The objective of our study was to analyze cryptic Y-chromosome derivatives in Hungarian TS patient population by real-time PCR (RT-PCR).

SUBJECTS AND METHODS

Cytogenetic and RT-PCR methods were used to examine peripheral blood DNA of 130 Hungarian patients with TS for the presence of Y-chromosome. With RT-PCR, 4 regions throughout the Y-chromosome were analyzed.

RESULTS

Initial cytogenetic karyotyping assessing 10-50 metaphases revealed 3 patients with Y-chromosome positivity. RT-PCR revealed further 6 patients with Y-chromosome, who were initially considered as Y-negatives by standard kayotyping. The consecutive cytogenetic analysis of a large number (about 100) of metaphases (in 5 patients) and/or FISH (in 6 patients) however, also confirmed the presence of the Y-chromosome in these patients. Prophylactic gonadectomy was carried out in all 9 patients and 1 of them was diagnosed as having bilateral gonadoblastoma without clinical symptoms.

CONCLUSIONS

We recommend a routine molecular screening for hidden Y-chromosome sequences in Turner patients, who are negative for Y-chromosome by conventional cytogenetic analysis, in order to calculate the future risk of developing gonadoblastoma.

Y chromosome in Turner syndrome: review of the literature

Turner syndrome (TS) is one of the most common types of aneuploidy among humans, and is present in 1:2000 newborns with female phenotype. Cytogenetically, the syndrome is characterized by sex chromosome monosomy (45,X), which is present in 50-60% of the cases. The other cases present mosaicism, with a 45,X cell line accompanied by one or more other cell lines with a complete or structurally abnormal X or Y chromosome. The presence of Y-chromosome material in patients with dysgenetic gonads increases the risk of gonadal tumors, especially gonadoblastoma. The greatest concern is the high risk of developing gonadoblastoma or other tumors and virilization during puberty if chromosome Y-specific sequences are present. The role of the Y chromosome in human oncogenesis is still controversial. Even though gonadoblastoma is a benign tumor, it can undergo transformation into invasive dysgerminoma in 60% of the cases, and also into other, malignant forms of germ cell tumors. Although some authors have questioned the high incidence of gonadoblastoma (around 30%), the risk of developing any kind of gonadal lesion, whether tumoral or not, justifies investigation of Y-chromosome sequences by means of the polymerase chain reaction (PCR), a highly sensitive, low-cost and easy-to-perform technique. In conclusion, mosaicism of both the X and the Y chromosome is a common finding in TS, and detection of Y-chromosome-specific sequences in patients, regardless of their karyotype, is necessary in order to prevent the development of gonadal lesions.

Chromosome territories, X;Y translocation and Premature Ovarian Failure: is there a relationship?

BACKGROUND

Premature ovarian failure (POF) is a secondary hypergonadotrophic amenorrhea occurring before the age of 40 and affecting 1-3% of females. Chromosome anomalies account for 6-8% of POF cases, but only few cases are associated with translocations involving X and Y chromosomes.This study shows the cytogenetic and molecular analysis of a POF patient came to our attention as she developed a left ovary choriocarcinoma at the age of 10 and at 14 years of age she presented secondary amenorrhea with elevated levels of gonadotropins.

RESULTS

Breakpoint position on X and Y chromosomes was investigated using Fluorescent In Situ Hybridisation (FISH) with a panel of specific BAC probes, microsatellite analysis and evaluation of copy number changes and loss of heterozigosity by Affymetrix(R) GeneChip platform (Santa Clara, CA, USA). Patient's karyotype resulted 46, X, der(Y)t(X;Y)(q13.1;q11.223). X inactivation study was assessed by RBA banding and showed preferential inactivation of derivative chromosome. The reciprocal spatial disposition of sexual chromosome territories was investigated using whole chromosome painting and centromeres probes: patient's results didn't show a significant difference in comparison to normal controls.

CONCLUSION

The peculiar clinical case come to our attention highlighted the complexity of POF aetiology and of the translocation event, even if our results seem to exclude any effect on nuclear organisation. POF phenotype could be partially explained by skewed X chromosome inactivation that influences gene expression.

Paternally derived der(7)t(Y;7)(p11.1 approximately 11.2;p22.3)dn in a mosaic case with Turner syndrome

An unusual mosaic karyotype was detected in a 6-year-old female patient with clinical diagnosis of Turner syndrome (TS). Cytogenetic and molecular cytogenetic studies revealed besides a cell line with 45,X a second cell line where the short arm of the Y-chromosome was translocated onto the short arm of a chromosome 7; karyotype: 45,X,der(7)t(Y;7)(p11.1 approximately 11.2;p22.3)/45,X. To delineate the mechanisms of rearrangement and karyotypic evolution in this case, further studies were performed. A maternal origin of the X-chromosome and biparental origin of both chromosomes 7 were determined by microsatellite analysis. Furthermore, using parental-origin-determination fluorescence in situ hybridization (pod-FISH) it could be established that the derivative chromosome 7 was of paternal origin. Overall, this is to the best of our knowledge the first report of such a complex mosaic TS karyotype.

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.

Neoplasms and pathology of sexual developmental disorders (intersex)

Continuing new insights into the biology of sexual development and advances in chromosome analysis have led to early identification and prompt treatment of the intersexual patient, the results of which facilitate a more normal life for affected individuals. Based on these advances, a classification of abnormal sexual development has been developed and refined that correlates the gonadal and genital anatomy with the chromosomal findings and specific genetic or metabolic defects. In a shift from a classification anchored on whether the intersex revolves about a specific gene or whole chromosomal abnormality, the current classification is organised by broader categories into which the intersexual disorders are divided into 'abnormalities of genital differentiation', due largely to the abnormal production or sensitivity of a single hormone, or 'abnormalities in sex determination', due to abnormal gonadal differentiation, usually testicular, with or without chromosomal aberration. The current classification is an integrated approach to this complex group of disorders and is organised according to the manner by which patients present as well as on the pathophysiological basis of the defect. The classification also groups patients who are at high risk for development of gonadal neoplasia.

Detection of hidden Y mosaicism in Turner's syndrome: importance in the prevention of gonadoblastoma

The presence of Y chromosome fragments in patients with Turner's syndrome (TS) is known to increase the risk of gonadoblastoma. The investigation of Y sequences is usually performed only in the presence of marker chromosomes and therefore does not rule out the presence of hidden mosaicism in patients with 45,X TS without any marker.

AIMS

1. To investigate the presence of hidden Y mosaicism in non-mosaic 45,X patients with TS, using samples from different tissues, and its association with the development of gonadoblastoma.

STUDY DESIGN

Twenty patients with a 45,X karyotype were studied. The SRY and DYZ3 sequences were amplified by PCR, using genomic DNA from peripheral blood, oral epithelial cells and hair roots. Prophylactic gonadectomy was offered to the Y-positive patients.

RESULTS

The analysis of the different tissues revealed that seven (35%) out of the 20 patients studied presented hidden chromosome Y mosaicism. Four of these patients underwent prophylactic gonadectomy, and bilateral gonadoblastoma was found in one of them.

CONCLUSIONS

A systematic search for hidden Y chromosome mosaicism in patients with TS and 45,X karyotype is justified by the possibility of developing gonadoblastoma.

[Gonadal dysgenesis and tumors: genetic and clinical features]

Gonadal dysgenesis comprises a clinical spectrum of anomalies in patients with female, ambiguous or male phenotype, absent or impaired puberty and karyotype with or without Y chromosome and/or chromosome markers. Although Y-specific sequences are seldom cytogenetically evident, dysgenetic gonads are potentially prone to developing tumors. Gonadoblastoma, a mixed germ cell and sex-cord cells tumor with variable degree of focal calcification, is the most harmful due to its frequency. Other gonadal tumor, malign or not, also occur in gonadal dysgenesis. As they are not metastatic tumors and may be eradicated by selective excisions, the importance of detecting Y-sequences by molecular sensitized techniques is stressed in order to indicate prophylactic gonadectomy.

Detection of low level sex chromosome mosaicism in Ullrich–Turner syndrome patients

Ullrich-Turner syndrome (UTS) is most commonly due to a 45,X chromosome defect, but is also seen in patients with a variety of X-chromosome abnormalities or 45,X/46,XY mosaicism. The phenotype of UTS patients is highly variable, and depends largely on the karyotype. Patients are at an increased risk of gonadoblastoma when a Y-derived chromosome or chromosome fragment is present. Since constitutional mosaicism is present in approximately 50% of UTS patients, the identification of minor cell populations is clinically important and a challenge to laboratories. We identified 50 females with a 45,X karyotype as the sole abnormality or as part of a more complex karyotype. Twenty two (44%) had a 45,X karyotype; mosaicism for a second normal or structurally abnormal X was observed in 24 (48%) samples, and mosaicism for Y chromosomal material in 4 (8%) cases. To further investigate the possibility of mosaicism in the 22 patients with an apparently non-mosaic 45,X karyotype, we performed FISH using centromere probes for the X and Y chromosomes. A minor XX cell line was identified in 3 patients, and the 45,X result was confirmed in 19 samples. No samples with XY mosaicism were identified. We describe our validation process for a FISH assay to be used in clinical practice to identify XX or XY mosaicism. FISH as an adjunct to karyotype analysis provides a sensitive and cost-effective technique to identify sex chromosome mosaicism in UTS patients.