Genetic heterogeneity of XY gonadal dysgenesis (Swyer syndrome): H-Y antigen-negative XY gonadal dysgenesis associated with inflammatory bowel disease

A 16 1/2-year-old girl was studied because of ileitis, lack of pubertal development, and primary amenorrhea. She had a 46,XY chromosome constitution in lymphocytes in fibroblasts without structural defects of X or Y. She was H-Y antigen negative. This observation supports the concept of causal heterogeneity of XY gonadal dysgenesis (Swyer syndrome). Two groups have been established: (1) H-Y antigen-positive forms, which are more common, possibly due to gonad-specific receptor defects (total failure or reduced receptor affinity), (2) H-Y antigen-negative forms possibly due to mutation in the H-Y generating system, either of the structural gene (presumably autosomal) or of a controlling gene (on the sex chromosomes). The H-Y antigen status may be of value in determining which patients are at risk for gonadoblastoma or dysgerminoma.     

Mapping a gene for 46,XY gonadal dysgenesis by linkage analysis

46,XY gonadal dysgenesis was transmitted as an autosomal-dominant trait in a large family with multiple affected members. Expressivity of the trait was highly variable, ranging from pure to partial gonadal dysgenesis associated with normal female genitalia or sexual ambiguity, to mild hypospadias in otherwise normal males. The phenotypic features of this trait appeared to be confined to the genitourinary system. Multipoint parametric analysis using markers D5S664, D5S633, and D5D2102 yielded an LOD score of 4.47, assuming sex-limited, autosomal-dominant inheritance with a penetrance of 0.6. Because mutation in testis-determining genes leads to gonadal dysgenesis in 46,XY individuals, we postulate that the gene mapped by this study normally plays a role in gonadal differentiation.     

A novel missense mutation in the HMG box region of the SRY gene in a Japanese patient with an XY sex reversal

The sex-determining region of the Y chromosome, the SRY gene, located on the short arm of the Y chromosome, is appreciated as one of the genes that is responsible for directing the process of sex differentiation. To date, 34 different mutations, including 29 missense and nonsense mutations in the SRY gene, have been described in XY female patients. We investigated the molecular basis of the sex reversal in one Japanese XY female patient by determining the nucleotide sequence of the SRY gene, using polymerase chain reaction and direct sequencing. We identified a novel mutation, of the substitution of Tyr for Asn at nucleotide position 87 (N87Y). This Asn residue is located within the DNA-binding high-mobility-group (HMG) motif, which is considered to be the main functional domain of the SRY protein. Further, this amino acid, Asn, is a conserved residue among mammalian SRY genes. These findings indicate that this amino acid substitution may be responsible for the sex reversal in this patient. Received: October 12, 1999 / Accepted: November 4, 1999     

Embryonic testicular regression sequence: A part of the clinical spectrum of 46, XY gonadal dysgenesis

With the identification of the cystic fibrosis (CF) gene and its major mutations in 1989, there has been considerable debate among health professionals as to whether population-based carrier testing should be instituted. This paper presents the results of a survey to determine the attitudes of physicians and genetics professionals towards CF carrier testing. Factors associated with differences in attitudes also were examined. A questionnaire was mailed to primary care physicians and psychiatrists in 10 states who graduated from medical school between 1950 and 1985. For comparison, medical geneticists and genetic counselors in the same states also received the questionnaire. A total of 1,140 primary care physicians and psychiatrists (64.8%) and 280 medical geneticists and genetic counselors (79.1%) responded. Although 92% of respondents believed that a couple should be tested after asking about a test that detected 80% of carriers, only 43.9% of respondents believed such a test should be offered routinely. Those specialists most likely to have been involved in genetic services were most opposed to routine screening. The most important reason reported for opposition to routine screening was the consequences of an 80% detection rate. When presented with a hypothetical “error-free” test, 75.9% of respondents favored routine testing. Our findings suggest that there was little support for routinely offering the CF carrier test available at the time of this study among the physicians and professionals most involved in the provision of genetic services. © 1994 Wiley-Liss, Inc.     

A novel SRY missense mutation affecting nuclear import in a 46,XY female patient with bilateral gonadoblastoma

Patients with disorders of sex development (DSD), especially those with gonadal dysgenesis and hypovirilization, are at risk of developing the so-called type II germ cell tumors (GCTs). Both carcinoma in situ and gonadoblastoma (GB) can be the precursor lesion, resulting in a seminomatous or non-seminomatous invasive cancer. SRY mutations residing in the HMG domain are found in 10–15% of 46,XY gonadal dysgenesis cases. This domain contains two nuclear localization signals (NLSs). In this study, we report a unique case of a phenotypical normal woman, diagnosed as a patient with 46,XY gonadal dysgenesis, with an NLS missense mutation, on the basis of the histological diagnosis of a unilateral GB. The normal role of SRY in gonadal development is the upregulation of SOX9 expression. The premalignant lesion of the initially removed gonad was positive for OCT3/4, TSPY and stem cell factor in germ cells, and for FOXL2 in the stromal component (ie, granulosa cells), but not for SOX9. On the basis of these findings, prophylactical gonadectomy of the other gonad was performed, also showing a GB lesion positive for both FOXL2 (ovary) and SOX9 (testis). The identified W70L mutation in the SRY gene resulted in a 50% reduction in the nuclear accumulation of the mutant protein compared with wild type. This likely explains the diminished SOX9 expression, and therefore the lack of proper Sertoli cell differentiation during development. This case shows the value of the proper diagnosis of human GCTs in identification of patients with DSD, which allows subsequent early diagnosis and prevention of the development of an invasive cancer, likely to be treated by chemotherapy at young age.     

No evidence of mutations in the follicle‐stimulating hormone receptor gene in Mexican women with 46,XX pure gonadal dysgenesis

In the ovary FSH is necessary for normal follicular development, binding to its receptor (FSHR) that pertains to the superfamily of G‐protein coupled receptors. In the FSHR gene, which consists of 10 exons, an homozygous mutation was reported in six Finnish families with gonadal dysgenesis; whereas two isolated French patients exhibited compound heterozygous mutations. Several groups, however, have searched for FSHR mutations, although in most cases the gene has been studied partially, not finding any genetic abnormalities in German, English, North American or Brazilian women. We performed direct sequencing of all 10 exons of the FSHR gene in seven sporadic patients and two sisters with 46,XX pure gonadal dysgenesis, to investigate the cause of their disorder. No heterozygous or homozygous mutant alleles were present in any of the patients. Although the number of patients evaluated was small, considering all the other previous reports, it seems that except in the Finnish population, the proportion of women with mutations in the encoding region of this gene is very low. Other possibilities for the presence of 46,XX gonadal dysgenesis, such as defects in the regulatory regions of the FSHR gene promoter, in the untranslated regions of exons 1 and 10, and within introns, or the existence of other genes likely to be important for normal ovarian function on the X chromosome or on autosomes, should be considered. In contrast with other studies, we did not find polymorphisms of the FSHR gene, indicating that apparently in Mexicans this gene is not highly polymorphic. © 2001 Wiley‐Liss, Inc.     

46,XY女性性反转患者SRY基因的一个新突变类型

目的 研究46，XY女性性反转患者发病的分子机理。方法 应用聚合酶链反应(polymerase chain reaction，PCR)扩增1例性反转患者和其父亲的．SRY基因片段；PCR产物连接到pUCm-T载体上，在ABI 377-3自动测序仪上完成测序以查明突变；应用PCR-限制性酶切对DNA测序的结果进行检测。结果 发现该患者的SRY基因存在点突变(T387A)，导致SRY蛋白发生氨基酸翻译终止(酪氨酸129终止密码)，患者父亲的序列正常。由于患者SRY序列中增加一个Mae Ⅱ酶切位点，PCR-限制性内切酶酶切电泳检测，结果显示患者出现3条带(131bp、231bp和247bp)，而正常人出现2条带(131bp和478bp)，进一步验证了序列分析的结果。经查证数据库，该突变是一个未见报道的新型．SRY基因突变。结论 这一新型突变的发现，有助于进一步阐明46，XY女性性反转发病的分子机理。     

Unilateral gonadal dysgenesis with both testis and fallopian tube on the same side in a 45,X/46,X INV (Y) mosaic male

A 5-year-old male with ambiguous external genitalia, hypospadias and microphallus without an urethral orifice was referred for cytogenetic studies. Exploratory laparotomy revealed presence of an infantile uterus and unilateral gonadal dysgenesis with both testes and fallopian tube on the right side. The metaphase cells from peripheral blood culture showed both 45,X/46,X inverted Y (p11.2q11.23) cell-lines (982). The inverted Y was found to be of paternal origin. Maternal chromosomal pattern was normal 46,XX. The presence of a fallopian tube next to testis suggest absence of secretion of anti-Mullerian hormone by Sertoli cells. The absence of Wolffian duct derivatives suggest insufficient secretion of testosterone by Leydig cells.     

Absence of inactivating mutations and deletions in the DMRT1 and FGF9 genes in a large cohort of 46,XY patients with gonadal dysgenesis

Despite advances in our understanding of the mechanisms involved in sex determination and differentiation, the specific roles of many genes in these processes are not completely understood in humans. Both DMRT1 and FGF9 are among this group of genes. Dmrt1 controls germ cell differentiation, proliferation, migration and pluripotency and Sertoli cell proliferation and differentiation. Fgf9 has been considered a critical factor in early testicular development and germ cell survival in mice. We screened for the presence of DMRT1 and FGF9 mutations in 33 patients with 46,XY gonadal dysgenesis. No deletions in either DMRT1 or FGF9 were identified using the MLPA technique. Eight allelic variants of DMRT1 were identified, and in silico analysis suggested that the novel c.968-15insTTCTCTCT variant and the c.774G>C (rs146975077) variant could have potentially deleterious effects on the DMRT1 protein. Nine previously described FGF9 allelic variants and six different alleles of the 3’ UTR microsatellite were identified. However, none of these DMRT1 or FGF9 variants was associated with increased 46,XY gonadal dysgenesis. In conclusion, our study suggests that neither DMRT1 nor FGF9 abnormalities are frequently involved in dysgenetic male gonad development in patients with non-syndromic 46,XY disorder of sex development.     

46,XX pure gonadal dysgenesis with growth hormone deficiency and impaired 3β-hydroxysteroid dehydrogenase activity

Patients with 46,XX pure gonadal dysgenesis generally are of normal stature and have less than usual amounts of pubic and axillary hair. We report on a patient who presented at age 11.9 years with short stature, absence of breast development, and excessive pubic hair. Her karyotype in leukocytes, fibroblasts, and streak gonad was 46,XX. The patient was diagnosed as having growth hormone deficiency. Elevated ACTH stimulated levels of 17-hydroxypregnenolone and dehydroepiandrosterone and elevated ACTH stimulated ratio of 17-hydroxypregnenolone to 17-hydroxyprogesterone suggested inadequate adrenal 3β-hydroxysteroid dehydrogenase activity. Treatment with growth hormone resulted in improvement in growth velocity and replacement with estrogen in feminization. We suggest that the finding of short stature in patients with 46, XX pure gonadal dysgenesis should not be attributed to the syndrome, but rather requires investigation for possible growth hormone deficiency. The poor growth of our patient prior to growth hormone replacement implies that dehydroepiandrosterone, unlike testosterone and estrogen, is ineffective in promoting linear growth in the absence of adequate growth hormone.     

Intratubular germ cell neoplasia in a man with ambiguous genitalia, 45,X/46,XY mosaic karyotype,and Y chromosome microdeletions

We report the case of a 17-yr-old male with ambiguous genitalia, 45,X/46,XY mosaic karyotype, and Y chromosome microdeletions. The patient underwent a testicular biopsy at the age of 6 with normal findings. A second biopsy at the age of 17 established the diagnosis of intratubular germ cell neoplasia (ITGCN), which was treated with bilateral orchidectomy. This case report deals with three important issues regarding ITGCN: First, although a prepubertal biopsy can be performed in order to provide evidence for future fertility, it is very unreliable for making a diagnosis of ITGCN. Second, because ITGCN tends to be a generalized procedure that affects both testes in a uniform pattern, a small number of biopsies, even a single one, could be adequate for diagnostic purposes in the majority of cases. Third, although the population that requires screening for ITGCN remains controversial, the early postpubertal period could be the optimum time for a testicular biopsy.     

Infant with mos45,X/46,XY/47,XYY/48,XYYY: Genetic and clinical findings

We describe an infant with mos45,X/46,XY/47,XYY/48,XYYY who presented with ambiguous genitalia. Her phenotype was also remarkable for minor ear and eye anomalies and coarctation of the aorta with bicuspid aortic valve. Laparoscopy revealed bilateral Fallopian tubes and a left infantile testis with epididymis. Chromosomal analyses of blood, skin, aorta, right Fallopian tube, and left gonadal tissue showed mos45,X/46,XY/47,XYY/48,XYYY. The 46,XY cell line was identified with routine trypsin-Giemsa banding only in cultured cells from an aortic biopsy. Fluorescence in-situ hybridization (FISH) was utilized to identify the presence of 46,XY cells in other tissues. The clinical manifestations of this patient are discussed and compared with those of similar cases of Y chromosome aneuploidy. To our knowledge, this is the first report of a patient with this unusual karyotype. © 1995 Wiley-Liss, Inc.     

Gene dosage imbalances in patients with 46,XY gonadal DSD detected by an in-house-designed synthetic probe set for multiplex ligation-dependent probe amplification analysis

The development of a testis requires the proper spatiotemporal expression of the SRY gene and other genes that act in a dosage-sensitive manner. Mutations in the SRY gene account for only 10–15% of patients with 46,XY gonadal disorder of sex development (DSD). To enable the diagnostics of deletions and duplications of genes known to be involved in different forms of DSD, we developed a synthetic probe set for multiplex ligation-dependent probe amplification (MLPA) analysis. Here, we report the results from the analysis of 22 patients with 46,XY gonadal DSD. The analysis with the DSD probe set has led to the identification of two copy number variations, an 800-kb NR0B1 ( DAX1 ) locus duplication on Xp21 in a patient with isolated partial gonadal dysgenesis and a duplication of the SRD5A2 gene that represents a rare normal variant. The described MLPA kit represents an optimal complement to DNA sequence analysis in patients with DSD, enabling screening for deletions and duplications of several genes simultaneously. Furthermore, the second identification of an NR0B1 locus duplication in a patient with isolated gonadal dysgenesis, without dysmorphic features and/or mental retardation, highlights the importance of evaluating NR0B1 duplication in patients with gonadal dysgenesis.     

Novel homozygous mutations in Desert hedgehog gene in patients with 46,XY complete gonadal dysgenesis and prediction of its structural and functional implications by computational methods

Male to female sex reversal in patients with 46,XY karyotype results from the failure of development of testis which may be due to mutations in the SRY gene. Only 10–15% of cases of 46,XY gonadal dysgenesis are accounted for by different types of mutations in the SRY gene. Hence, majority of such patients may have mutations in other genes involved in the testicular differentiation pathway. Besides SRY, other autosomal and X-linked genes are also involved in sexual development during embryogenesis. We describe here the first report from India wherein, two cases of 46,XY complete gonadal dysgenesis that could be attributable to mutations in the Desert hedgehog (DHH) gene. The mutations found in these two patients were a homozygous deletion (c.271_273delGAG) that resulted in deletion of one amino acid (p.D90del) and a homozygous duplication (c.57–60dupAGCC) that resulted in premature termination resulting in non-functional DHH protein. The structure–function implications of the p.D90del mutation were predicted using computational tools. Structural studies on the p.D90del mutant revealed that the mutation could seriously perturb the interaction of DHH with its binding partners. This is the second report in literature showing homozygous mutation in cases with 46,XY complete gonadal dysgenesis.