A novel mutation of desert hedgehog in a patient with 46,XY partial gonadal dysgenesis accompanied by minifascicular neuropathy

We describe a patient with 46,XY partial gonadal dysgenesis (PGD) who presented with polyneuropathy. Sural nerve pathology revealed peculiar findings characterized by extensive minifascicular formation within the endoneurium and with a decreased density of myelinated fibers. We found, in the patient, a homozygous missense mutation (ATG-->ACG) at the initiating codon in exon 1 of the desert hedgehog (DHH) gene, which predicts a failure of translation of the gene. The same heterozygous mutation was found in the patient's father. This is the first report of a human DHH gene mutation, and the findings demonstrate that mutation of the DHH gene may cause 46, XY PGD associated with minifascicular neuropathy.     

A novel missense mutation (S18N) in the 5′ non-HMG box region of the SRY gene in a patient with partial gonadal dysgenesis and his normal male relatives

Mutations in the sex-determining region of the Y chromosome (the SRY gene) have been reported in low frequency in patients with 46,XY gonadal dysgenesis. We investigated 21 Brazilian 46,XY sex-reversed patients, who presented either complete or partial gonadal dysgenesis or embryonic testicular regression syndrome. Using Southern blotting, polymerase chain reaction, denaturing gradient gel electrophoresis and direct sequencing, we analyzed deletions and point mutations in the SRY gene. We found a missense mutation at codon 18 upstream of the 5′ border of the HMG box of the SRY gene in one patient with partial gonadal dysgenesis. This variant sequence was also found in DNA obtained from blood and sperm cells of his father and in blood cells of his normal brother. The S18N mutation was not found in 50 normal males, ruling out the possibility of a common polymorphism. We identified a novel familial missense mutation (S18N) in the 5’ non-HMG box of the SRY gene in 1 of 21 patients with 46,XY sex reversal. Received: 6 May 1997 / Accepted: 2 October 1997     

Peer Victimization Experienced by Children and Adolescents Who Are Deaf or Hard of Hearing

Victimization is a relatively common, yet serious problem, with potentially severe consequences for children''s psychosocial and academic functioning. Children who are Deaf or Hard of Hearing (DHH) may be at a higher risk for victimization than hearing children. The aims of the present study were to compare DHH and hearing children on i) self-reported experiences of victimization and ii) associations between victimization, parental- and child variables. In total 188 children (mean age 11;11 years) from the Netherlands and Dutch-speaking part of Belgium participated in the study. No difference between DHH and hearing children were found on general experiences of victimization. However, differences between the groups were found on specific forms of experienced victimization and on the associations between victimization and parental variables. For DHH children, parental sensitivity and parents who challenge their DHH children to become competent in the practical, emotional, cognitive and social domain is associated with them being less victimized. For hearing children at this age these relations were reversed, absent or more complex. Finally, DHH children in special schools were more victimized than DHH children in regular schools. It can be concluded that parents can play an important role in reducing social problems experienced by DHH children and young adolescents.     

The binding of dehydroheliotridine to DNA and the effect of it and other compounds on repair synthesis in main and satellite band DNA.

This study was aimed at elucidating the mechanisms of the preferential depression of satellite DNA synthesis by dehydroheliotridine (DHH). DHH was found to induce repair synthesis to the same extent in both main and satellite band DNA in cultured sheep lymphocytes. This was also the case with acridine orange, nitrogen mustard (HN2) and ethyl methane-sulphonate (EMS). Using analytical equilibrium ultracentrifugation no difference was found between the extents of in vitro binding of DHH by main and satellite band DNA. From these results it was concluded that the depression of the synthesis of satellite DNA could not be explained by either its preferential binding of DHH or by less effective repair mechanisms. Radiolabelled DHH when added to synchronized cultures of ovine kidney cells was found to be preferentially bound to the satellite DNA (one DHH molecule to 6000 nucleotides) compared with the main band DNA (one to 10 000). When 5-bromodeoxyuridine (BUdR) was added to the cultures no DHH label was found in the heavy, semiconservatively replicated DNA band. From these findings it is suggested that attack may occur during mitosis where all of the satellite DNA may be undergoing synthesis at the same time, thus explaining the increased amount of DHH bound to the satellite.     

Description and molecular analysis of SRY and AR genes in a patient with 46,XY pure gonadal dysgenesis (Swyer syndrome)

46,XY pure gonadal dysgenesis, first described in 1955 by Swyer, results from testicular tissue loss during the first 8 weeks of fetal life, a critical period for male differentiation. We describe a case of an 18 years old patient presented to us with a chief complain of primary amenorrhea. Chromosomal analysis revealed a 46,XY karyotype. A molecular investigation was undertaken in an attempt to determine mutations in SRY and AR genes through DNA sequencing. Mutations were shown to be absent. The molecular basis of Swyer syndrome is still unknown, although the presence of mutations in testicular organizing genes downstream of SRY is still to rule out. The patient, who is considered as female, was placed on estrogen replacement therapy, while bilateral prophylactic laparoscopic gonadectomy was programmed due to the high prevalence of gonadal tumors in this syndrome. No signs of malignance were detected in the gonadal tissue, which predicts that an intact SRY gene is usually, but not always, not related to the formation of malignancies like dysgeminomas or gonadoblastomas.     

St?rungen der m?nnlichen Gonadendifferenzierung

XY gonadal dysgenesis is characterized by a failure of testis differentiation and can be caused either by disturbed development of the urogenital ridge to the bipotential gonad or by impaired differentiation of the bipotential gonad to testis. Genes responsible for early gonadal development like WT1 and SF1 can be distinguished from genes involved in testis differentiation such as SRY, SOX9, DMRT, DAX1, WNT4, DHH, CBX2, TSPYL1, ATRX and ARX. In complete XY gonadal dysgenesis, M??llerian but no Wolffian structures are present. In partial XY gonadal dysgenesis, remnants of M??llerian and Wolffian ducts can be present and virilization of the external genitalia can take place. In about a third of cases, XY gonadal dysgenesis occurs in a syndromic form. In these syndromic forms, the extragenital phenotypes can indicate the causative genes, but these genes can also cause non-syndromic forms of XY gonadal dysgenesis.     

Desert hedgehog (Dhh) gene is required in the mouse testis for formation of adult-type Leydig cells and normal development of peritubular cells and seminiferous tubules

Testes from adult and prepubertal mice lacking the Desert hedgehog (DHH:) gene were examined in order to describe further the role of Dhh in spermatogenesis because, in a previous report, DHH:-null male mice were shown to be sterile. Dhh is a signaling molecule expressed by Sertoli cells. Its receptor, patched (Ptc), has been previously localized to Leydig cells and is herein described as being localized also to peritubular cells. Two phenotypes of the mice were observed: masculinized (7.5% of DHH:-null males) and feminized (92.5%), both of which displayed abnormal peritubular tissue and severely restricted spermatogenesis. Testes from adult feminized animals lacked adult-type Leydig cells and displayed numerous undifferentiated fibroblastic cells in the interstitium that produced abundant collagen. The basal lamina, normally present between the myoid cells and Sertoli cells, was focally absent. We speculate that the abnormal basal lamina contributed to other characteristics, such as extracordal gonocytes, apolar Sertoli cells, and anastomotic seminiferous tubules. The two DHH:-null phenotypes described have common peritubular cell defects that may be indicative of the essential role of peritubular cells in development of tubular morphology, the differentiation of Leydig cells, and the ultimate support of spermatogenesis.     

Mesonephric FGF signaling is associated with the development of sexually indifferent gonadal primordium in chick embryos

The gonad as well as the reproductive tracts, kidney, and adrenal cortex are derived from the intermediate mesoderm. In addition, the intermediate mesoderm forms the mesonephros. Although the mesonephros is the source of certain testicular cell types, its contribution to gonad formation through expression of growth factors is largely unknown. Here, we examined the expression profiles of FGF9 in the developing mesonephros of chick embryos at sexually indifferent stages, and found that the expression domain is adjacent to the gonadal primordium. Moreover, FGFR3 (FGF receptor 3) showed a strong expression in the gonadal primordium. Next, we examined the functions of FGF signal during gonadal development with misexpressed FGF9. Interestingly, misexpression of FGF9 led to gonadal expansion through stimulation of cell proliferation. In contrast, treatment with a chemical inhibitor for FGFR decreased cell proliferation and resulted in reduction of the gonadal size. Simultaneously, the treatment resulted in reduction of gonadal marker gene expression. Our study demonstrated that FGF expressed in the developing mesonephros is involved in the development of the gonad at the sexually indifferent stages through stimulation of gonadal cell proliferation and gonadal marker gene expression.     

Seminiferous cord formation is regulated by hedgehog signaling in the marsupial

The signaling molecule DHH, secreted by Sertoli cells, has essential regulatory functions in testicular differentiation. DHH is required for the differentiation of peritubular myoid cells that line the seminiferous cords and steroidogenic Leydig cells. The testicular cords in Dhh-null male mice lack a basal lamina and develop abnormally. To date, the DHH-signaling pathway has never been examined outside of any eutherian mammals. This study examined the effects of inhibition of DHH signaling in a marsupial mammal, the tammar wallaby, by culturing gonads in vitro in the presence of the hedgehog-signaling inhibitors cyclopamine and forskolin. Disruption of hedgehog signaling in the tammar testes caused highly disorganized cord formation. SOX9 protein remained strongly expressed in Sertoli cells, laminin distribution was highly fragmented, and germ cells were distributed around the cortical regions of treated testes in an ovarianlike morphology. This suggests that hedgehog signaling regulates cord formation in the tammar wallaby testis as it does in eutherian mammals. These data demonstrate that the hedgehog pathway has been highly conserved in mammals for at least 160 million years.     

Requirements for scribble expression in newly formed gonads of Drosophila embryos

The tumour suppressor gene scribble (scrib) is required for epithelial polarity and growth control in Drosophila, and encodes two protein isoforms. Here, we report the pattern of Scrib1 synthesis in pole cells and embryonic gonads. We found that Scrib1 synthesis became strongly enhanced in pole cells at the time of gonad formation and was also detectable in cortical domains of gonadal mesodermal cells adjacent to pole cells. Scrib1 synthesis in mesodermal cells was independent of pole cells and occurred in agametic valois and capsuléen embryonic gonads. In contrast, Scrib1 synthesis in pole cells required contact with gonadal mesodermal cells as revealed by the absence of Scrib1 in wunen or tinman-zinc finger homeodomain-1 pseudo-gonads made only of aggregated pole cells.     

Sex-specific apoptosis regulates sexual dimorphism in the Drosophila embryonic gonad

Sexually dimorphic development of the gonad is essential for germ cell development and sexual reproduction. We have found that the Drosophila embryonic gonad is already sexually dimorphic at the time of initial gonad formation. Male-specific somatic gonadal precursors (msSGPs) contribute only to the testis and express a Drosophila homolog of Sox9 (Sox100B), a gene essential for testis formation in humans. The msSGPs are specified in both males and females, but are only recruited into the developing testis. In females, these cells are eliminated via programmed cell death dependent on the sex determination regulatory gene doublesex. Our work furthers the hypotheses that a conserved pathway controls gonad sexual dimorphism in diverse species and that sex-specific cell recruitment and programmed cell death are common mechanisms for creating sexual dimorphism.     

True hermaphroditism in a 46,XY individual, caused by a postzygotic somatic point mutation in the male gonadal sex-determining locus (SRY): molecular genetics and histological findings in a sporadic case.

Recently, the gene for the determination of maleness has been identified in the sex-determining region on the short arm of the Y chromosome (SRY) between the Y-chromosomal pseudoautosomal boundary (PABY) and the ZFY gene locus. Experiments with transgenic mice confirmed that SRY is a part of the testis-determining factor (TDF). We describe a sporadic case of a patient with intersexual genitalia and the histological finding of ovotestes in the gonad, which resembles the mixed type of gonadal tissue without primordial follicle structures. The karyotype of the patient was 46,XY. By PCR amplification, we tested for the presence of PABY, SRY, and ZFY by using DNA isolated from peripheral blood leukocytes and for the presence of SRY by using DNA obtained from histological gonadal slices. The SRY products of both DNA preparations were further analyzed by direct sequencing. All three parts of the sex-determining region of the Y chromosome could be amplified from leukocytic DNA. The patient's and the father's SRY sequences were identical with the published sequence. In the SRY PCR product of gonadal DNA, the wild-type and two point mutations were present in the patient's sequence, simulating a heterozygous state of a Y-chromosomal gene: one of the mutations was silent, while the other encoded for a nonconservative amino acid substitution from leucine to histidine. Subcloning procedures showed that the two point mutations always occurred together. The origin of the patient's intersexuality is a postzygotic mutation of the SRY occurring in part of the gonadal tissue. This event caused the loss of the testis-determining function in affected cells.     

Estrogen-Independent Ovary Formation in the Medaka Fish, Oryzias latipes

To investigate whether a female sex steroid, estrogen, acts as a natural inducer of female gonadal sex determination (or ovary formation) in the medaka fish, Oryzias latipes, the effects of an aromatase inhibitor and anti-estrogens on sexual differentiation of gonads were examined. We found that both drugs did not show any discernible effects on the genetically determined sex differentiation in both sexes. However, the aromatase inhibitor impaired the paradoxical effects of androgen (a male sex steroid), and the anti-estrogens inhibited the male-to-female sex reversal caused by estrogen. Treatments of the fertilized eggs with androgen disturbed the gonadal sex developments in both sexes, suggesting that sex steroid synthesis is detrimental to the gonadal sex developments in the medaka embryos. These results are consistent with the previous observation that sex steroids are not synthesized before the onset of gonadal sex differentiation, and suggest that ovary formation in the genetic females of the medaka fish is not dependent on estrogen.     

Somatic origin of inherited haemophilia A

Summary We found a partial deletion of the clotting factor VIII gene of about 2000 bp, spanning exon 5 and part of intervening sequence 4 and 5 in an isolated patient with severe haemophilia A. The mother of the patient, who appeared to be a non-carrier on the basis of coagulation assays and restriction fragment length polymorphism analysis in the family, turned out to be a mosaic for the deletion, not only in her germ cells, but also in various somatic cells. These findings suggest that the mutation is the result of an event in early embryogenesis. If mosaicism for a mutation, either gonadal or somatic, proves to be a common phenomenon in human genetics, it is imperative to reconsider genetic risks for (future) sibs of any apparently new mutant of a hereditary disease.     

Role of gonadal dysgenesis in gonadoblastoma induction in 46, XY individuals. The Leuven experience in 46, XY pure gonadal dysgenesis and testicular feminization syndromes.

To stress the importance of gonadal dysgenesis in the genesis of gonadoblastoma in the presence of the Y-chromosome, the authors report their experience on 7 patients with 46, XY Pure Gonadal Dysgenesis (PGD) and 14 patients with complete or incomplete forms of Testicular Feminization (TF) syndrome. The diagnostic criteria and the clinical and pathological findings are reviewed. Four patients with PGD were found to be affected by bilateral (1 patient) or unilateral (1 patient) gonadoblastomas, and by extragonadal (1 patient) or gonadal (1 patient) dysgerminoma, whereas no gonadal tumors were encountered in testes of patients with complete (CTF) or incomplete (ITF) forms of TF, underlining the pathogenic role of the gonadal dysgenesis.     

Molecular investigation of the parental origin of a de novo unbalanced translocation 13/18

We report a patient with a de novo translocation 13/18, identified by high-resolution banding. The breakpoints were ascertained by fluorescence in situ hybridisation with whole chromosome 13 and 18 paints. Short tandem repeat typing demonstrated the aberration to be of combined maternal/paternal origin and thereby confirmed its de novo and postzygotic formation. Thus, a gonadal mosaic in one of the parents resulting in a higher recurrence risk could be excluded. Received: 1 September 1996 / Revised: 3 November 1996     

Failure of testicular development associated with a rearrangement of 9p24.1 proximal to the SNF2 gene

In 46,XY individuals, testes are determined by the activity of the SRY gene (sex-determining region Y), located on the short arm of the Ychromosome. The other genetic components of the cascade that leads to testis formation are unknown and may be located on the Xchromosome or on the autosomes. Evidence for the existence of several loci associated with failure of male sexual development is indicated by reports of 46,XY gonadal dysgenesis associated with structural abnormalities of the Xchromosome or of autosomes (chromosomes9, 10, 11 and 17). In this report, we describe the investigation of a child presenting with multiple congenital abnormalities, mental retardation and partial testicular failure. The patient had a homogeneous de novo 46,XY,inv dup(9)(pter→p24.1::p21.1 →p23.3::p24.1→qter) chromosome complement. No deletion was found by either cytogenetic or molecular analysis. The SRY gene and DSS region showed no abnormalities. Southern blotting dosage analysis with 9p probes and fluorescent in situ hybridisation data indicated that the distal breakpoint of the duplicated fragment was located at 9p24.1, proximal to the SNF2 gene. We therefore suggest that a gene involved in normal testicular development and/or maintenance is present at this position on chromosome 9. Received: 20 January 1997 / Accepted: 5 November 1997