Ovarian gonadoblastoma with mixed germ cell tumor in a woman with 46, XX karyotype and successful pregnancies

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.

Gonadoblastoma with Dysgerminoma Presenting as Virilizing Disorder in a Young Child with 46, XX Karyotype: A Case Report and Review of the Literature

Gonadoblastoma is a neoplasm containing an intimate mixture of germ cells and elements resembling immature granulosa or Sertoli cells. It has been considered as in situ germ cell malignancy that can be associated with malignant components. The tumor has been reported to almost exclusively develop in various types of gonadal gene mutation syndromes, such as in pure or mixed gonadal dysgenesis and among females carrying Y chromosome material. However, it can be rarely present in normal women with 46, XX karyotype. Ovarian gonadoblastoma presenting with signs of contrasexual puberty in a young female child with normal 46, XX karyotype is an extremely rare clinical entity and seldom reported in the literature. We report a case of a nine-year-old girl child who presented with signs of virilization and contrasexual pubertal development. A detailed clinical evaluation along with supportive biochemical and radiological findings pointed to the presence of a virilizing ovarian tumor. The patient underwent right salpingo-oophorectomy, pelvic node dissection, and infracolic omentectomy. The excised tumor was confirmed to be gonadoblastoma which was overgrown by dysgerminoma on histopathological evaluation. The presence of associated malignant tumors (like dysgerminoma) should always be ruled out in cases of gonadoblastoma.

Dissecting Gonadoblastoma of the Ovary Coexistent with an Atypical Endometriotic Cyst: Incidental Detection in Cystectomy Specimen of a Woman with 46,XX Karyotype

Dissecting gonadoblastoma (DGB) of the ovary, a recently described terminology, defines a unique distribution of neoplastic germ cells. Here, we report a case of incidental DGB coexistent with an atypical endometriotic cyst occurring in a 23-year-old woman. The ovarian cyst was lined by endometrial-like glands and stroma. Some glands displayed nuclear enlargement and hyperchromasia, and abundant eosinophilic cytoplasm with occasional intracytoplasmic hemosiderin and mucin vacuoles. The neoplastic germ cells resembled those of ovarian dysgerminoma and were diffusely distributed within the ovarian stroma, which was stretched around the wall of the endometriotic cyst. These cells were arranged in nests and cords, possessing clear cytoplasm and centrally located round nuclei with prominent nucleoli and occasional mitoses. Chromosomal analysis revealed a 46,XX karyotype. We describe the clinical, histological, immunophenotypical, and genetic features of ovarian DGB incidentally detected in the ovarian cystectomy specimen of a woman with normal female karyotype.

Ovarian gonadoblastoma with dysgerminoma in a girl with 46,XX karyotype 17a-hydroxylase/17, 20-lyase deficiency: A case report and literature review

17α-hydroxylase/17,20-lyase deficiency (17-OHD), caused by mutations in the gene of the cytochrome P450 family 17 subfamily A member 1 (CYP17A1), is a rare type of congenital adrenal hyperplasia (CAH), usually characterized by cortisol and sex steroid deficiency combined with excessive mineralocorticoid. Gonadoblastoma is a relatively rare ovarian tumor that is frequently seen among patients with 46,XY gonadal dysgenesis. Rarely have they been reported in female patients with normal 46,XX karyotype. Here, we report an interesting case of an 11-year-old Chinese girl who presented acute abdominal pain that was later attributed to tumor rupture of right ovarian gonadoblastoma with dysgerminoma. Further evaluations revealed hypertension and hypokalemia. Hormonal findings showed increased progesterone, hypergonadotropic hypogonadism, and low cortisol levels. Her chromosome karyotype was 46,XX without Y chromosome material detected. Genetic analysis revealed that the patient had a homozygous pathogenic variant c.985_987delTACinsAA (p.Y329Kfs*90) in exon 6 of the CYP17A1 gene and that her parents were all heterozygous carriers of this pathogenic variant. Due to the variable clinical manifestations of 17-OHD, meticulous assessment including genetic analysis is necessary. Further study is warranted to unravel the mechanism of gonadoblastoma in a patient with normal karyotypes.

Canine ovarian gonadoblastoma with dysgerminoma overgrowth: a case study and literature review

BACKGROUND

Gonadoblastoma (GB) is a rare mixed germ cell-sex cord-stromal tumour, first described in humans, commonly found in dysgenetic gonads of intersex patients that have a Y chromosome. However, this entity in not recognized in the WHO classification of tumours of genital system of domestic animals. Herein, we describe a case of ovarian gonadoblastoma with proliferation of dysgerminoma and sex cord-stromal tumour components, in a phenotypically and cytogenetically normal bitch.

CASE PRESENTATION

A 17-year-old cross-breed bitch had a firm, grey-white multinodular mass in the left ovary. The tumour was submitted to histopathological examination and Y chromosome detected through karyotype analysis and PCR studies. Microscopically, the ovary was almost replaced by an irregular neoplasm composed of three distinct, intermixed elements: dysgerminoma, mixed germ cell-sex cord-stromal tumour resembling human GB and a proliferative sex cord-stromal tumour component. The germ cells of gonadoblastoma and dysgerminoma components were immunoreactive for c-KIT. Sex cord-stromal cells of gonadoblastoma were immunoreactive for α-inhibin. The sex cord-stromal tumour was immunoreactive for AE1/AE3, occasionally for α-inhibin and negative for epithelial membrane antigen (EMA). The karyotype was 78, XX and PCR analysis confirmed the absence of the Y chromosome.

CONCLUSION

Based on these findings, a diagnosis of gonadoblastoma with proliferation of dysgerminoma and sex cord-stromal tumour was made. This is the first case of ovarian gonadoblastoma in a female dog.

Imaging findings of ovarian dysgerminoma with emphasis on multiplicity and vascular architecture: pathogenic implications

We report the imaging findings of three ovarian dysgerminomas that coexisted with other germ cell tumors or gonadoblastomas, focusing on the distribution of tumor nests and vascular architecture, which might provide information about the pathogenesis of dysgerminomas. In a 14-year-old female with dysgerminoma and coexisting gonadoblastomas, contrast-enhanced magnetic resonance imaging (MRI) demonstrated a solid mass in the right ovary, which presented as hyperintense lobules on diffusion-weighted imaging separated by fibrovascular septa. Some small nodules were found to exist separately from the lobules (multiplicity) and to include pathological remnants of gonadoblastoma. Large tumor vessels were present at the center of the mass (central blood vessels), which were in direct contact with the ovarian veins and radiated peripherally through the fibrovascular septa. In a 35-year-old female, a mixed germ cell tumor, which was mainly composed of dysgerminoma and yolk sac tumor foci, exhibited the same vascular architecture pattern as the first dysgerminoma on contrast-enhanced computed tomography. In a 10-year-old female with a mixed germ cell tumor, contrast-enhanced MRI revealed an enlarged left ovary, which contained a large heterogeneous mass and multiple tiny nodules (multiplicity). Microscopically, the former corresponded to a yolk sac tumor, and the latter corresponded to a dysgerminoma containing remnants of gonadoblastoma. Based on these cases, the presence of tumor nest multiplicity and central blood vessels might aid the diagnosis of dysgerminoma, and these imaging findings might be indicative of the synchronous development of multiple dysgerminomas from primordial germ cells or gonadoblastomas.

Mixed Gonadal Germ Cell Tumor Composed of a Spermatocytic Tumor-Like Component and Germinoma Arising in Gonadoblastoma in a Phenotypic Woman With a 46, XX Peripheral Karyotype: Report of the First Case

We report a unique case of gonadal mixed germ cell tumor (GCT) composed of a predominantly spermatocytic tumor (ST)-like component and a minor component of germinoma arising in gonadoblastoma in a phenotypic woman with a 46, XX peripheral karotype. The patient was a 24-year-old woman (gravida 2, para 1) found to have a 7 cm pelvic mass during routine obstetric ultrasound examination at 20 weeks gestational age. She underwent a left salpingo-gonadectomy at gestational age 23 and 2/7 weeks. She recovered well and delivered a healthy baby at full term. The resected gonadal tumor measured 7.5 cm and microscopically was composed of 3 morphologically distinct components: gonadoblastoma (1%), germinoma (1%) and a ST-like component (98%). The ST-like component was composed of 3 populations of tumor cells: small cells, intermediate and large sized cells, similar to testicular ST. Scattered binucleated and multinucleated cells were present. Immunohistochemically the ST-like component was positive for pan-GCT markers SALL4 and LIN28 but with weaker staining than the germinoma. It was negative for OCT4 and TCL1. Only rare tumor cells were positive for SOX17. In contrast, the germinoma cells were diffusely and strongly positive for SALL4, LIN28, OCT4, SOX17, and TCL1. CD117 was positive in both the germinoma and ST-like component but with fewer tumor cells positive in the latter. Flurorescence in situ hybridization study demonstrated isochromosome 12p in the germinoma component but not in the gonadoblastoma and ST-like component. This patient did not receive further chemoradiation therapy after the surgery. She has been free of disease for 10 years and 1 month since her surgery. To our knowledge, this is the first case report of a ST-like GCT in a phenotypic female.

Increased risk of gonadal malignancy and prophylactic gonadectomy: a study of 102 phenotypic female patients with Y chromosome or Y-derived sequences

STUDY QUESTION

What is the optimal protocol of management for phenotypic female patients with Y chromosome or Y-derived sequences, in particular for adult patients?

SUMMARY ANSWER

Immediate gonadectomy, long-term hormone therapy and psychological care are suggested to be the optimal management for older phenotypic female patients with Y chromosome or Y-derived sequences.

WHAT IS KNOWN ALREADY

Phenotypic female patients with Y chromosome or Y-derived sequences are at increasing risk of developing gonadal tumors with age. Early diagnosis and safe guidelines of management for these patients are needed.

STUDY DESIGN, SIZE, DURATION

One hundred and two phenotypic women with Y chromosome or Y-derived sequences were included in a straightforward, retrospective-observational study conducted over a period of 26 years from January 1985 to November 2010.

PARTICIPANTS/MATERIALS, SETTING AND METHODS

Patients aged 16-34 years presenting to our Academic Department of Gynecology with symptoms of disorders of sex development were subjected to history taking, hormonal evaluation, conventional cytogenetic analysis, PCR, histopathology and immunohistochemistry. Features of the gonads were examined and the outcome of prophylactic gonadectomy evaluated.

MAIN RESULTS AND THE ROLE OF CHANCE

Among the patients recruited in our study, 48 patients (47.1%) were diagnosed with complete/partial androgen insensitivity syndrome (CAIS/PAIS) (46XY), 33 cases (32.4%) with gonadal dysgenesis (46XY) and the remaining subjects (20.1%) with mixed gonadal dysgenesis (with sex chromosome structural abnormalities). The total incidence of malignancy was 17.6%. Seventeen patients (16.7%) had gonadoblastoma, while one patient (1.0%) with gonadal dysgenesis had dysgerminoma. Gonadoblastoma were observed in 2/21 patients with sex chromosome structural abnormalities (9.5%), 3/33 patients with gonadal dysgenesis (9.1%), 9/30 patients with CAIS (30.0%) and 3/18 patients with PAIS (16.7%).

LIMITATIONS, REASONS FOR CAUTION

Selection bias in this cohort study may affect data interpretation due to the low incidence of disorders of sex development in the general population.

WIDER IMPLICATIONS OF THE FINDINGS

The risk for malignant transformation may occur in early life and highly increase with age in patients with Y chromosome or Y-derived sequences. Optimal timing of gonadectomy should be decided by multiple factors including the subgroup of disorder, age and degree of patient's maturity. In addition, gonadal biopsy is suggested when the disease is diagnosed and any evidence of premalignancy warranties gonadectomy.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Key Scientific Research Project (2013CB967404), Natural Science Funds of Zhejiang Province (Y13H04005), Zhejiang Qianjiang talent plan (2013R10027), the Fundamental Research Funds for the Central Universities and Key Projects in the National Science & Technology Pillar Program during the Eleventh Five-Year Plan Period (2012BAI32B04). The authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER None.

Endometrial carcinoma with yolk sac tumor-like differentiation and elevated serum β-hCG: a case report and literature review

Endometrial carcinoma with a germ cell tumor component is a rare event. Here we report a uterine neoplasm with a unique combination of endometrioid adenocarcinoma and mixed germ cell malignant elements. A 28-year-old woman with abnormal vaginal bleeding, an abdominal mass, and elevated alfa-fetoprotein and beta-human chorionic gonadotropin (β-hCG) levels had a history of biopsy of an omental mass and chemotherapy in another hospital one month before her referral to our department. Histologic examination of the mass removed from the omentum revealed an endometrioid adenocarcinoma with yolk sac tumor-like differentiation. Total abdominal hysterectomy, bilateral salpingo-oophorectomy, infracolic omentectomy, and removal of metastatic disease were then undertaken at our hospital. Postoperative chemotherapy was given. Eight months postoperatively, serum alfa-fetoprotein and β-hCG rose again. Cases with primary yolk sac tumors of the endometrium or endometrial carcinoma with trophoblastic differentiation in the literature were reviewed.

Molecular characteristics of malignant ovarian germ cell tumors and comparison with testicular counterparts: implications for pathogenesis

This review focuses on the molecular characteristics and development of rare malignant ovarian germ cell tumors (mOGCTs). We provide an overview of the genomic aberrations assessed by ploidy, cytogenetic banding, and comparative genomic hybridization. We summarize and discuss the transcriptome profiles of mRNA and microRNA (miRNA), and biomarkers (DNA methylation, gene mutation, individual protein expression) for each mOGCT histological subtype. Parallels between the origin of mOGCT and their male counterpart testicular GCT (TGCT) are discussed from the perspective of germ cell development, endocrinological influences, and pathogenesis, as is the GCT origin in patients with disorders of sex development. Integrated molecular profiles of the 3 main histological subtypes, dysgerminoma (DG), yolk sac tumor (YST), and immature teratoma (IT), are presented. DGs show genomic aberrations comparable to TGCT. In contrast, the genome profiles of YST and IT are different both from each other and from DG/TGCT. Differences between DG and YST are underlined by their miRNA/mRNA expression patterns, suggesting preferential involvement of the WNT/β-catenin and TGF-β/bone morphogenetic protein signaling pathways among YSTs. Characteristic protein expression patterns are observed in DG, YST and IT. We propose that mOGCT develop through different developmental pathways, including one that is likely shared with TGCT and involves insufficient sexual differentiation of the germ cell niche. The molecular features of the mOGCTs underline their similarity to pluripotent precursor cells (primordial germ cells, PGCs) and other stem cells. This similarity combined with the process of ovary development, explain why mOGCTs present so early in life, and with greater histological complexity, than most somatic solid tumors.

Testicular gonadoblastoma in two pet domestic rabbits (Oryctolagus cuniculus domesticus)

Testicular gonadoblastoma is an uncommon tumor in domestic animals. The current study describes a testicular gonadoblastoma in 2 pet domestic rabbits ( Oryctolagus cuniculus domesticus) based on the histomorphological, immunohistochemical, and ultrastructural characteristics of the tumor. The tumor tissue consisted of discrete tubular structures separated by a fibrous stroma. The tubular structures were composed of large round cells similar in appearance to germ cells in the seminiferous tubules, and small spindle cells with oval or elongated nuclei resembling Sertoli cells. The spindle cells showed peculiar structural patterns arranged in a coronal or follicular pattern, often forming Call–Exner bodies like those in an ovarian granulosa cell tumor. One case was concomitant with seminoma. Immunohistochemistry revealed large round cells that were positive for c-kit and placental alkaline phosphatase, while spindle cells were positive for vimentin and Wilms tumor protein. Ultrastructurally, the spherical eosinophilic material (Call–Exner body) consisted of duplicated basal lamina, and sex cord components surrounded a single degenerative cell similar to a germ cell.

The chromosome Y-linked testis-specific protein locus TSPY1 is characteristically present in gonadoblastoma

Gonadoblastoma is a rare gonadal neoplasm that occurs almost exclusively in individuals who are phenotypically females. Most cases develop in women who have an abnormal karyotype in which at least a portion of the centromeric region of the short arm of chromosome Y is present, a region often referred to as the GBY locus. Of the several genes present in the GBY locus, the TSPY1 gene (which encodes testis-specific protein, a protein thought to have a role in cell cycle regulation) appears to be the most likely to have a critical role in the pathogenesis of gonadoblastoma. To evaluate the association of TSPY1 with the tumor, we developed an interphase fluorescent in situ hybridization assay that uses probes that target the region of the GBY locus that contains TSPY1 and a commercially available chromosome X CEP probe. Using this set of probes in a dual-color approach, we evaluated 6 cases of gonadoblastoma identified from our files and found that both TSPY1 and chromosome X were present in 5 (84%) of 6 cases; in these 5 cases, the adjacent nonneoplastic gonadal parenchyma showed the same genotype as the tumor. Of 6 cases, 1 (16%) showed no evidence of TSPY1; in this case, which occurred in a gravida 2 para 2 woman, 2 X chromosomes were present in the nonneoplastic ovary, the gonadoblastoma, and associated dysgerminoma and granulosa cell tumors. From a basic science perspective, our data demonstrate that the TSPY1 gene is present in most gonadoblastomas, supporting the hypothesized role for TSPY1 in gonadoblastoma tumorigenesis; the lack of TSPY1 in a fertile woman suggests that other loci can, however, substitute for TSPY1 in the development of the tumor. From a clinical perspective, our data show that interphase fluorescence in situ hybridization targeting TSPY1 is a straightforward approach that can be used in the evaluation of Y-associated intersex disorders in women who develop gonadoblastoma.

Recent Advances in the Pathology and Classification of Gonadal Neoplasms Composed of Germ Cells and Sex Cord Derivatives

In recent years, our understanding of neoplasms composed of germ cells and sex cord derivatives has increased. In this review, advances in the classification and pathology of ovarian germ cell-sex cord-stromal tumors are discussed. Only 2 neoplasms, each with a distinctive pathogenesis and clinicopathologic features, are included in this category. Gonadoblastoma is a tumor that usually occurs in the dysgenetic gonads of intersex patients that have a Y chromosome, whereas mixed germ cell-sex cord-stromal tumor arises in normal gonads in patients without sex chromosomal abnormalities. Ovarian mixed germ cell-sex cord-stromal tumors differ from their testicular counterparts in their histological appearance, immunohistochemical staining reactions, and biological behavior probably because the latter show a greater degree of maturity of their germ cell component. The introduction of cisplatin-based chemotherapy and the application of tumor markers have dramatically improved the clinical outlook for those patients who develop secondary malignant germ cell neoplasms.

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.

Gonadoblastoma in Turner syndrome and Y-chromosome-derived material

The identification of Y-chromosome material is important in females with Ullrich-Turner syndrome (UTS) due to the risk of developing gonadoblastoma or other gonadal tumors. There is controversy regarding the frequency of the Y-chromosome-derived material and the occurrence of gonadoblastoma in these patients. The aim of our study was to evaluate a large number of patients with UTS, followed before and during the pubertal age for the prevalence of Y-chromosome derived material, the occurrence of gonadoblastoma, and the incidence of possible neoplastic degeneration. An unselected series of 171 patients with UTS (1-34 years old), diagnosed cytogenetically, was studied for Y-chromosome markers (SRY and Y-centromeric DYZ3 repeats). The follow-up was of 2-22 years; 101 of these patients were followed during pubertal age. Y-chromosome material was found in 14 patients (8%): 12 of these were gonadectomized (2.8-25.9 years). A gonadoblastoma was detected in four patients under 16 years of age: in two, Y-material was detected only at molecular analysis (at conventional cytogenetic analysis, one was included in the 45,X group and one in the X + mar group) and one had also an immature teratoma and an endodermal sinus carcinoma. The prevalence of gonadoblastoma in our series of gonadectomized UTS patients with Y-positive material was of 33.3% (4/12). Our data suggest that the age of appearance and the possibility of malignant degeneration of gonadoblastoma can occur early in life. These patients, in particular those with 45,X or a marker chromosome may benefit from molecular screening to detect the presence of Y-chromosome material; PCR is a rapid and inexpensive technique. At the moment, laparoscopy and preventive gonadectomy performed as soon as possible remain the procedures of choice for patients with UTS, when Y-chromosome has been identified, as we are still unable to predict a future malignant evolution of gonadoblastoma.

Gonadoblastoma: evidence for a stepwise progression to dysgerminoma in a dysgenetic ovary

Gonadoblastomas are neoplasms of dysgenetic gonads which may undergo regression or become overgrown by malignant germ cell tumors (mGCTs). Since little is known about their relationship to normal gonadal development and mGCTs, we studied the phenotype and antigenic profile of gonadoblastomas in comparison with adjacent dysgerminomas and fetal gonads. Three cases of gonadoblastomas and fetal gonads of both sexes were analyzed using oncofetal markers to M2A-antigen (M2A), germ cell alkaline phosphatase (PLAP/GCAP), receptor tyrosine kinase c-kit (c-kit), and somatic angiotensin converting enzyme (sACE) as well as the proliferation marker MIB-1. Morphologically, microfollicular pattern of gonadoblastomas showed a fetal germ cell organization reminiscent of oocytic clusters of fetal ovaries. They contained both cell types, similar to oocytes (M2A-, GCAP-, c-kit+/-, sACE-) and oogonia (M2A+, GCAP+, c-kit+, sACE+). The percentage of germ cells immunoreactive for oncofetal markers and the proliferation index increased from microfollicular over coronary patterns to adjacent dysgerminomas. Supportive cells of gonadoblastomas showed a uniform phenotype (CK18+, vimentin+, sACE+, alpha-inhibin+, M2A-) but in contrast to fetal germ cells lacked a clear equivalence to fetal tissues. Our results show that gonadoblastomas mimic female fetal ovary and exhibit a stepwise progression from follicular pattern to coronary pattern and finally to dysgerminomas.

Gonadoblastoma in a patient with del(9)(p22) and sex reversal: report of a case and review of the literature

Studies of distinct clinical prototypes have significantly contributed to our understanding of evolutionary abnormalities and their association with neoplasia. We describe a phenotypic female, aged 20 years at report, who was examined as an infant for developmental retardation. The clinical characteristics of the 9p- syndrome were present and the external genitalia were those of a normal female. The karyotype was 46XY,del(9)(p22). The parental karyotypes were normal. No SRY deletion or mutation was detected. Sonography showed the presence of a uterus. Basal luteinizing hormone values were normal; follicle stimulating hormone values were high (40 IU/L). Stimulation with human chorionic gonadotropin did not produce any rise in testosterone. The gonads were removed and histologic analysis disclosed dysgenetic gonads with gonadoblastoma in situ. This case constitutes the fourth case of gonadoblastoma developing in an individual with 9p- syndrome and sex reversal. This and analogous prototypes point to a locus (or loci) on the short arm of chromosome 9, which either constitutes a nonspecific suppressor gene or a gonadoblastoma suppressor gene. An alternative hypothesis would be that a gonad not normally differentiated is more prone to gonadoblastoma development without any specific gene involvement.