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

A germline chimeric KANK1-DMRT1 transcript derived from a complex structural variant is associated with a congenital heart defect segregating across five generations

Structural variants (SVs) pose a challenge to detect and interpret, but their study provides novel biological insights and molecular diagnosis underlying rare diseases. The aim of this study was to resolve a 9p24 rearrangement segregating in a family through five generations with a congenital heart defect (congenital pulmonary and aortic valvular stenosis and pulmonary artery stenosis), by applying a combined genomic analysis. The analysis involved multiple techniques, including karyotype, chromosomal microarray analysis (CMA), FISH, genome sequencing (GS), RNA-seq, and optical genome mapping (OGM). A complex 9p24 SV was hinted at by CMA results, showing three interspersed duplicated segments. Combined GS and OGM analyses revealed that the 9p24 duplications constitute a complex SV, on which a set of breakpoints matches the boundaries of the CMA duplicated sequences. The proposed structure for this complex rearrangement implies three duplications associated with an inversion of ~ 2 Mb region on chromosome 9 and a SINE element insertion at the more distal breakpoint. Interestingly, this genomic structure of rearrangement forms a chimeric transcript of the KANK1/DMRT1 loci, which was confirmed by both RNA-seq and Sanger sequencing on blood samples from 9p24 rearrangement carriers. Altogether with breakpoint amplification and FISH analysis, this combined approach allowed a deep characterization of this complex rearrangement. Although the genotype-phenotype correlation remains elusive from the molecular mechanism point of view, this study identified a large genomic rearrangement at 9p24 segregating with a familial congenital heart defect, revealing a genetic biomarker that was successfully applied for embryo selection, changing the reproductive perspective of affected individuals.

A germline chimeric KANK1-DMRT1 transcript derived from a complex structural variant is associated with a congenital heart defect segregating across five generations

Structural variants (SVs) pose a challenge to detect and interpret, but their study provides novel biological insights and molecular diagnosis underlying rare diseases. The aim of this study was to resolve a 9p24 rearrangement segregating in a family through five generations with a congenital heart defect (congenital pulmonary and aortic valvular stenosis, and pulmonary artery stenosis), by applying a combined genomic analysis. The analysis involved multiple techniques, including karyotype, chromosomal microarray analysis (CMA), FISH, whole-genome sequencing (WGS), RNA-seq and optical genome mapping (OGM). A complex 9p24 SV was hinted at by CMA results, showing three interspersed duplicated segments. Combined WGS and OGM analyses revealed that the 9p24 duplications constitute a complex SV, on which a set of breakpoints match the boundaries of the CMA duplicated sequences. The proposed structure for this complex rearrangement implies three duplications associated with an inversion of ~ 2Mb region on chromosome 9 with a SINE element insertion at the more distal breakpoint. Interestingly, this hypothesized genomic structure of rearrangement forms a chimeric transcript of the KANK1/DMRT1 loci, which was confirmed by RNA-seq on blood from 9p24 rearrangement carriers. Altogether with breakpoint amplification and FISH analysis, this combined approach allowed a deep characterization of this complex rearrangement. Although the genotype-phenotype correlation remains elusive from the molecular mechanism point of view, this study identified a large genomic rearrangement at 9p segregating with a familial congenital clinical trait, revealing a genetic biomarker that was successfully applied for embryo selection, changing the reproductive perspective of affected individuals.

EARLY-ONSET GONADOBLASTOMA IN A 13-MONTH-OLD INFANT WITH 46,XY COMPLETE GONADAL DYSGENESIS IDENTIFIED WITH PRENATAL TESTING: A CASE OF CHROMOSOME 9p DELETION

Objective

Individuals with 46,XY complete gonadal dysgenesis (CGD) are at high risk of developing gonadal neoplasms. Chromosome 9p monosomy with deletion of the DMRT1 gene, a key transcription factor in testicular development, is one of the known causes of 46,XY CGD. Noninvasive prenatal testing (NIPT) is being increasingly used, and can identify disorders of sexual development (DSDs).

Methods

We report the case of a 46,XY infant with phenotypically female external genitalia, müllerian structures including uterus and fallopian tubes, and bilateral streak gonads who was found to have unilateral gonadoblastoma at 13 months. 46,XY DSD was suggested prenatally when discordance between NIPT and fetal ultrasound was noted.

Results

Genetic investigation revealed a deletion of 12.5 million base pairs at chromosome 9p24.3, which includes the doublesex and MAB-3-related transcription factor-1 (DMRT1) gene.

Conclusion

Current guidelines recommend gonadectomy at the time of diagnosis in cases of 46,XY CGD, and our patient had gonadoblastoma at 13 months. 46,XY DSD, including rare disorders such as CGD, will be increasingly identified before birth with more widespread use of NIPT, raising the question about the appropriate timing of gonadectomy in prenatal diagnoses. Our case supports the current recommendation to perform gonadectomy as early as possible after diagnosis.

Male Reproductive Disorders and Fertility Trends: Influences of Environment and Genetic Susceptibility

It is predicted that Japan and European Union will soon experience appreciable decreases in their populations due to persistently low total fertility rates (TFR) below replacement level (2.1 child per woman). In the United States, where TFR has also declined, there are ethnic differences. Caucasians have rates below replacement, while TFRs among African-Americans and Hispanics are higher. We review possible links between TFR and trends in a range of male reproductive problems, including testicular cancer, disorders of sex development, cryptorchidism, hypospadias, low testosterone levels, poor semen quality, childlessness, changed sex ratio, and increasing demand for assisted reproductive techniques. We present evidence that several adult male reproductive problems arise in utero and are signs of testicular dysgenesis syndrome (TDS). Although TDS might result from genetic mutations, recent evidence suggests that it most often is related to environmental exposures of the fetal testis. However, environmental factors can also affect the adult endocrine system. Based on our review of genetic and environmental factors, we conclude that environmental exposures arising from modern lifestyle, rather than genetics, are the most important factors in the observed trends. These environmental factors might act either directly or via epigenetic mechanisms. In the latter case, the effects of exposures might have an impact for several generations post-exposure. In conclusion, there is an urgent need to prioritize research in reproductive physiology and pathophysiology, particularly in highly industrialized countries facing decreasing populations. We highlight a number of topics that need attention by researchers in human physiology, pathophysiology, environmental health sciences, and demography.

Duplication 9p and their implication to phenotype

Background

Trisomy 9p is one of the most common partial trisomies found in newborns. We report the clinical features and cytogenomic findings in five patients with different chromosome rearrangements resulting in complete 9p duplication, three of them involving 9p centromere alterations.

Methods

The rearrangements in the patients were characterized by G-banding, SNP-array and fluorescent in situ hybridization (FISH) with different probes.

Results

Two patients presented de novo dicentric chromosomes: der(9;15)t(9;15)(p11.2;p13) and der(9;21)t(9;21)(p13.1;p13.1). One patient presented two concomitant rearranged chromosomes: a der(12)t(9;12)(q21.13;p13.33) and an psu i(9)(p10) which showed FISH centromeric signal smaller than in the normal chromosome 9. Besides the duplication 9p24.3p13.1, array revealed a 7.3 Mb deletion in 9q13q21.13 in this patient. The break in the psu i(9)(p10) probably occurred in the centromere resulting in a smaller centromere and with part of the 9q translocated to the distal 12p with the deletion 9q occurring during this rearrangement. Two patients, brother and sister, present 9p duplication concomitant to 18p deletion due to an inherited der(18)t(9;18)(p11.2;p11.31)mat.

Conclusions

The patients with trisomy 9p present a well-recognizable phenotype due to facial appearance, although the genotype-phenotype correlation can be difficult due to concomitant partial monosomy of other chromosomes. The chromosome 9 is rich in segmental duplication, especially in pericentromeric region, with high degree of sequence identity to sequences in 15p, 18p and 21p, chromosomes involved in our rearrangements. Thus, we suggest that chromosome 9 is prone to illegitimate recombination, either intrachromosomal or interchromosomal, which predisposes it to rearrangements, frequently involving pericentromeric regions.

Pathway-based analysis of GWAs data identifies association of sex determination genes with susceptibility to testicular germ cell tumors

Genome-wide association (GWA) studies of testicular germ cell tumor (TGCT) have identified 18 susceptibility loci, some containing genes encoding proteins important in male germ cell development. Deletions of one of these genes, DMRT1, lead to male-to-female sex reversal and are associated with development of gonadoblastoma. To further explore genetic association with TGCT, we undertook a pathway-based analysis of SNP marker associations in the Penn GWAs (349 TGCT cases and 919 controls). We analyzed a custom-built sex determination gene set consisting of 32 genes using three different methods of pathway-based analysis. The sex determination gene set ranked highly compared with canonical gene sets, and it was associated with TGCT (FDRG = 2.28 × 10(-5), FDRM = 0.014 and FDRI = 0.008 for Gene Set Analysis-SNP (GSA-SNP), Meta-Analysis Gene Set Enrichment of Variant Associations (MAGENTA) and Improved Gene Set Enrichment Analysis for Genome-wide Association Study (i-GSEA4GWAS) analysis, respectively). The association remained after removal of DMRT1 from the gene set (FDRG = 0.0002, FDRM = 0.055 and FDRI = 0.009). Using data from the NCI GWA scan (582 TGCT cases and 1056 controls) and UK scan (986 TGCT cases and 4946 controls), we replicated these findings (NCI: FDRG = 0.006, FDRM = 0.014, FDRI = 0.033, and UK: FDRG = 1.04 × 10(-6), FDRM = 0.016, FDRI = 0.025). After removal of DMRT1 from the gene set, the sex determination gene set remains associated with TGCT in the NCI (FDRG = 0.039, FDRM = 0.050 and FDRI = 0.055) and UK scans (FDRG = 3.00 × 10(-5), FDRM = 0.056 and FDRI = 0.044). With the exception of DMRT1, genes in the sex determination gene set have not previously been identified as TGCT susceptibility loci in these GWA scans, demonstrating the complementary nature of a pathway-based approach for genome-wide analysis of TGCT.

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.

Prenatal diagnosis and molecular cytogenetic characterization of a de novo pure distal 9p deletion and literature review

We present rapid aneuploidy diagnosis of distal 9p deletion by array comparative genomic hybridization using uncultured amniocytes in a pregnancy associated with an abnormal maternal serum screening result and intrauterine growth restriction (IUGR) in the fetus. We review the literature of prenatal diagnosis of distal 9p deletion, and add abnormal maternal serum biochemistry and fetal IUGR in the distinctive prenatal findings in pregnancy with fetal distal 9p deletion. We discuss the consequence of haploinsufficiency of DOCK8, KANK1, VLDLR and DMRT1 in this case.

Dysregulation of the mitosis-meiosis switch in testicular carcinoma in situ

Testicular germ cell tumours (TGCT) of young adults arise from the intratubular precursor, carcinoma in situ (CIS). CIS cells are thought to be developmentally arrested and transformed fetal germ cells that survive through childhood and gain invasive capacity after puberty. Given that germ cell neoplasms arise frequently in undervirilized and dysgenetic gonads and the striking physiological difference between meiotic entry in ovaries (fetal life) versus testes (at puberty), this study aimed to investigate whether errors in regulation of meiosis may be implicated in the pathogenesis of CIS or its invasive progression to TGCT. The main focus was on a key sex differentiation and meiosis regulator, DMRT1, which has also been linked to TGCT risk in recent genetic association studies. Expression patterns of DMRT1 and other meiosis regulators (SCP3, DMC1, STRA8, CYP26B1, NANOS2, NANOS3) were investigated in pre- and post-pubertal CIS samples and TGCT by quantitative RT-PCR and immunohistochemistry. The results demonstrated that meiosis markers and meiosis inhibitors were simultaneously expressed in CIS cells, in both pre- and post-pubertal testis samples. DMRT1 was present in a restricted subset of CIS cells, which was relatively greater in pre-pubertal (27%) compared to adult (2.6%) samples. In contrast to the majority of CIS cells, DMRT1-positive CIS cells in adult testes were not proliferating. DMRT1 and most of the other meiosis regulators were absent or expressed at low levels in invasive TGCT, except in spermatocytic seminoma (not derived from CIS). In conclusion, this study indicates that meiosis signalling is dysregulated in CIS cells and that a key regulator of the mitosis-meiosis switch, DMRT1, is expressed in 'early-stage' CIS cells but is down-regulated with further invasive transformation. Whether this mixed meiosis signalling in CIS cells is caused by insufficient virilization of the fetal somatic niche or a partial post-pubertal maturation remains uncertain and requires further study.

Chromosome 9p deletion syndrome and sex reversal: novel findings and redefinition of the critically deleted regions

Deletions of the short arm of chromosome 9 are associated with two distinct clinical entities. Small telomeric 9p24.3 deletions cause genital anomalies in male subjects, ranging from disorder of gonadal sex to genital differentiation anomalies, while large terminal or interstitial deletions result in 9p-malformation syndrome phenotype. The critical region for non-syndromic 46,XY sex reversal was assigned to a 1 Mb interval of chromosome 9p, extending from the telomere to the DMRT genes cluster. The 9p-syndrome was assigned to bands 9p22.3p24.1, but a phenotypic map has not been established for this condition, probably because of the lack of detailed molecular and/or phenotypic characterization, as well as frequent involvement of additional chromosome rearrangements. Here, we describe a unique patient with a small isolated 9p terminal deletion, characterized by array-CGH and FISH, who shows a complex phenotype with multiple physical anomalies, resembling the 9p-syndrome, disorder of sex development with gonadoblastoma, congenital heart defect and epilepsy. The observed deletion includes the 46,XY sex-reversal critical region, excluding the region so far associated with the 9p-syndrome. Genotype-phenotype correlations are tentatively established comparing our patient to seven other previously reported males with isolated terminal 9p deletions, finely defined at a molecular level. Our observations expand the 9p deletion clinical spectrum, and add significantly to the definition of a 9p-syndrome critical region.

Characterization of a complex rearrangement involving duplication and deletion of 9p in an infant with craniofacial dysmorphism and cardiac anomalies

Partial duplication and partial deletion of the short arm of chromosome 9 have each been reported in the literature as clinically recognizable syndromes. We present clinical, cytogenetic, and molecular findings on a five-week-old female infant with concomitant duplication and terminal deletion of the short arm of chromosome 9. To our knowledge ten such cases have previously been reported. Conventional cytogenetic analysis identified additional material on chromosome 9 at band p23. FISH analysis aided in determining the additional material consisted of an inverted duplication with a terminal deletion of the short arm. Microarray analysis confirmed this interpretation and further characterized the abnormality as a duplication of about 32.7 Mb, from 9p23 to 9p11.2, and a terminal deletion of about 11.5 Mb, from 9p24.3 to 9p23. The infant displayed characteristic features of Duplication 9p Syndrome (hypotonia, bulbous nose, single transverse palmar crease, cranial anomalies), as well as features associated with Deletion 9p Syndrome (flat nasal bridge, long philtrum, cardiac anomalies) despite the deletion being distal to the reported critical region for this syndrome. This case suggests that there are genes or regulatory elements that lie outside of the reported critical region responsible for certain phenotypic features associated with Deletion 9p Syndrome. It also underscores the importance of utilizing array technology to precisely define abnormalities involving the short arm of 9p in order to further refine genotype/phenotype associations and to identify additional cases of duplication/deletion.

Inv dup del(9p): prenatal diagnosis and molecular cytogenetic characterization by fluorescence in situ hybridization and array comparative genomic hybridization

OBJECTIVE

To present molecular cytogenetic characterization of prenatally detected inverted duplication and deletion of 9p, or inv dup del(9p).

MATERIALS, METHODS, AND RESULTS

A 35-year-old primigravid woman underwent amniocentesis at 16 weeks of gestation because of advanced maternal age. Amniocentesis revealed a derivative chromosome 9, or der(9) with additional material at the end of the short arm of one chromosome 9. Parental karyotypes were normal. Level II ultrasound showed ventriculomegaly and normal male external genitalia. Repeated amniocentesis was performed at 20 weeks of gestation. Array comparative genomic hybridization revealed a 0.70-Mb deletion at 9p24.3 and an 18.36-Mb duplication from 9p24.3 to 9p22.1. The distal 9p deletion encompassed the genes of DOCK8, ANKRD15, FOXD4, DMRT1, and DMRT3. Fluorescence in situ hybridization analysis using bacterial artificial chromosome clone probes specific for 9p confirmed that the der(9) was derived from the inv dup del(9p). The karyotype of the fetus was 46,XY,inv dup del(9)(:p22.1-->p24.3::p24.3-->qter)dn or 46,XY,der(9) del(9)(p24.3) inv dup(9)(p22.1p24.3)dn. Polymorphic DNA marker analysis determined a maternal origin of the inv dup del(9p). A 512-g male fetus was subsequently terminated at 22 weeks of gestation with facial dysmorphism. The fetus had normal male external genitalia without sex reversal.

CONCLUSION

Fluorescence in situ hybridization and array comparative genomic hybridization are useful to determine the nature of a prenatally detected aberrant chromosome derived from the inv dup del. Male fetuses with inv dup del(9p) and haploinsufficiency of DMRT1 and DMRT3 may present normal male external genitalia without sex reversal.

Genome-wide association studies provide new insights into the genetic basis of testicular germ-cell tumour

Testicular germ-cell tumour (TGCT) is the most common cancer in young men, and genetic epidemiological studies suggest that the disease has a strong genetic basis. Until 2009, very little of this genetic component had been explained. Genome-wide association studies have since identified eight SNPs at six loci which together account for approximately 15% of the genetic risk of TGCT and offer novel biological insights into testicular germ-cell oncogenesis. In this review, we summarize the genetic epidemiology of TGCT, detail the contribution genome-wide association studies have made to our understanding of the genetic basis of TGCT and reflect on how future technological advances may assist in revealing the remaining genetic factors underlying TGCT susceptibility.

A second independent locus within DMRT1 is associated with testicular germ cell tumor susceptibility

Susceptibility to testicular germ cell tumors (TGCT) has a significant heritable component, and genome-wide association studies (GWASs) have identified association with variants in several genes, including KITLG, SPRY4, BAK1, TERT, DMRT1 and ATF7IP. In our GWAS, we genotyped 349 TGCT cases and 919 controls and replicated top hits in an independent set of 439 cases and 960 controls in an attempt to find novel TGCT susceptibility loci. We identified a second marker (rs7040024) in the doublesex and mab-3-related transcription factor 1 (DMRT1) gene that is independent of the previously described risk allele (rs755383) at this locus. In combined analysis that mutually conditions on both DMRT1 single nucleotide polymorphism markers, TGCT cases had elevated odds of carriage of the rs7040024 major A allele [per-allele odds ratio (OR) = 1.48, 95% confidence interval (CI) 1.23, 1.78; P = 2.52 × 10(-5)] compared with controls, while the association with rs755383 persisted (per allele OR = 1.26, 95% CI 1.08, 1.47, P = 0.0036). In similar analyses, the association of rs7040024 among men with seminomatous tumors did not differ from that among men with non-seminomatous tumors. In combination with KITLG, the strongest TGCT susceptibility locus found to date, men with TGCT had greatly elevated odds (OR = 14.1, 95% CI 5.12, 38.6; P = 2.98 × 10(-7)) of being double homozygotes for the risk (major) alleles at DMRT (rs7040024) and KITLG (rs4474514) when compared with men without TGCT. Our findings continue to corroborate that genes influencing male germ cell development and differentiation have emerged as the major players in inherited TGCT susceptibility.

Testicular germ cell tumours: predisposition genes and the male germ cell niche

Testicular germ cell tumours (TGCTs) of adults and adolescents are putatively derived from primordial germ cells or gonocytes. Recently reported genome-wide association studies implicate six gene loci that predispose to TGCT development. Remarkably, the functions of proteins encoded by genes within these regions bridge our understanding between the pathways involved in primordial germ cell physiology, male germ cell development and the molecular pathology of TGCTs. Furthermore, this improved understanding of the mechanisms underlying TGCT development and dissemination has clinical relevance for the management of patients with these tumours.

Variants near DMRT1, TERT and ATF7IP are associated with testicular germ cell cancer

We conducted a genome-wide association study for testicular germ cell tumor, genotyping 298,782 SNPs in 979 affected individuals and 4,947 controls from the UK and replicating associations in a further 664 cases and 3,456 controls. We identified three new susceptibility loci, two of which include genes that are involved in telomere regulation. We identified two independent signals within the TERT-CLPTM1L locus on chromosome 5, which has previously been associated with multiple other cancers (rs4635969, OR=1.54, P=1.14x10(-23); rs2736100, OR=1.33, P=7.55x10(-15)). We also identified a locus on chromosome 12 (rs2900333, OR=1.27, P=6.16x10(-10)) that contains ATF7IP, a regulator of TERT expression. Finally, we identified a locus on chromosome 9 (rs755383, OR=1.37, P=1.12x10(-23)), containing the sex determination gene DMRT1, which has been linked to teratoma susceptibility in mice.

[Chromosome 9P deletion: Gonadal dysgenesis associated with mental retardation and hypoplasia of the corpus callosum: A contiguous gene syndrome?]

BACKGROUND

Many genes are involved in testicular differentiation. The alterations of these genes are responsible for sexual differentiation disorders with 46 XY karyotype.

CASE

We report the case of a newborn who had an interscrotal hypospadias, palpable gonads and hypoplastic penis. Karyotype 46 XY. Abdominal ultrasound revealed testes and absence of Müllerian remnants. There was a good response to the short gonadotrophin test. At one year he had signs of psychomotor retardation and hypotonia. The magnetic resonance revealed frontal-temporal atrophy and a decrease in the corpus callosum. Testicular biopsy was compatible with gonadal dysgenesis. A preoperative cystography showed a vaginal remnant. Due to the presence of a sexual differentiation disorder, psychomotor retardation and facial dysmorphism, we requested a high-resolution karyotype: deletion 46, XY, del (9p) (p23-pter). Ish tel (9p-).

DISCUSSION

Many genes are involved in testicular differentiation, some of which also affect the development of other tissues. In the short arm of chromosome 9, two genes, DMRT1 and DMRT2, are involved in sexual differentiation. Their alterations have also been described as causing mental retardation. In the evaluation of 46,XY disorders of sex differentiation, the accompanying signs are very important for guiding the genetic study.

Cytogenetic and array-CGH characterization of a complex de novo rearrangement involving duplication and deletion of 9p and clinical findings in a 4-month-old female

Approximately 15 patients with partial trisomy 9p involving de novo duplications have been previously described. Here, we present clinical, cytogenetic, FISH and aCGH findings in a patient with a de novo complex rearrangement in the short arm of chromosome 9 involving an inverted duplication at 9p24→p21.3 and a deletion at 9pter→p24.2. FISH probes generated from BACs selected from the UCSC genome browser were utilized to verify this rearrangement. It is likely that some previously described duplications of 9p may also be products of complex chromosomal aberrations. This report in which FISH and aCGH were used to more comprehensively characterize the genomic rearrangement in a patient with clinical manifestations of 9p duplication syndrome underscores the importance of further characterizing cytogenetically detected rearrangements.

Characterization of deletions at 9p affecting the candidate regions for sex reversal and deletion 9p syndrome by MLPA

The distal region on the short arm of chromosome 9 is of special interest for scientists interested in sex development as well as in the clinical phenotype of patients with the 9p deletion syndrome, characterized by mental retardation, trigonocephaly and other dysmorphic features. Specific genes responsible for different aspects of the phenotype have not been identified. Distal 9p deletions have also been reported in patients with 46,XY sex reversal, with or without 9p deletion syndrome. Within this region the strongest candidates for the gonadal dysgenesis phenotype are the DMRT genes; however, the genetic mechanism is not clear yet. Multiple ligation-dependent probe amplification represents a useful technique to evaluate submicroscopic interstitial or distal deletions that would help the definition of the minimal sex reversal region on 9p and could lead to the identification of gene(s) responsible of the 46,XY gonadal disorders of sex development (DSD). We designed a synthetic probe set that targets genes within the 9p23-9p24.3 region and analyzed a group of XY patients with impaired gonadal development. We characterized a deletion distal to the DMRT genes in a patient with isolated 46,XY gonadal DSD and narrowed down the breakpoint in a patient with a 46,XY del(9)(p23) karyotype with gonadal DSD and mild symptoms of 9p deletion syndrome. The results are compared with other patients described in the literature, and new aspects of sex reversal and the 9p deletion syndrome candidate regions are discussed.

Imaging of the unusual pediatric 'blastomas'

‘Blastomas’ are tumors virtually unique to childhood. Controversy surrounds their nomenclature and there is no globally accepted classification. They are thought to arise from immature, primitive tissues that present persistent embryonal elements on histology, affect a younger pediatric population and are usually malignant. The ‘commoner’ blastomas (neuroblastoma, nephroblastoma, hepatoblastoma, medulloblastoma) account for approximately 25% of solid tumors in the pediatric age range. We present examples of the more unusual blastematous pediatric tumors (lipoblastoma, osteoblastoma, chondroblastoma, hemangioblastoma, gonadoblastoma, sialoblastoma, pleuropulmonary blastoma, pancreatoblastoma, pineoblastoma, and medullomyoblastoma) that were recorded in our institution. Although these rare types of blastomas individually account for <1% of pediatric malignancies, collectively they may be responsible for up to 5% of pediatric tumors in a given population of young children. Imaging is often non-specific but plays an important role in their identification, management and follow-up. Some characteristic imaging features at diagnosis, encountered in cases diagnosed and treated in our institution, are described and reviewed.

Drosophila spermatogenesis: insights into testicular cancer

Geneticists have a long history of studying reproduction in the fruitfly, Drosophila melanogaster, and in recent years it has become apparent that many of the genes that regulate invertebrate reproduction have been conserved through vertebrate evolution. As with other higher eukaryotes, spermatogenesis in Drosophila is characterized by a regenerative germline stem cell population that divides asymmetrically to produce mitotic spermatogonia which will eventually differentiate into spermatocytes. Germline tumours consisting of undifferentiated germ cells have been associated with both loss-of-function mutations and ectopic gene expression. While the genesis of these tumours may not be identical to human germ cell tumours many of the genes that regulate stem cell proliferation and aberrant over-proliferation in the Drosophila testis provide candidate molecules that may underlie the genetic programmes that contribute to human testicular oncogenesis.

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.

Analysis of SRY gene in 8 cases of sex abnormality

In order to investigate the relationship between sex dysplasia and sex-determining region Y (SRY) gene, 8 patients with sexual abnormality were analyzed by cytogenetic and molecular genetic methods. Fluorescence in situ hybridization (FISH) using PY3.4, X alpha satellite, and SRY probes was performed in each case to analyze the sex chromosome translocation and gene translocation. SRY gene was amplified by polymerase chain reaction (PCR) and its mutation was detected by direct sequencing. The results showed that among 8 patients, 5 were positive for SRY and the remaining negative for SRY. In the patients positive for SRY genes, 3 presented testes and the left 2 streak ovaries. In the patients negative for SRY, only one case presented testes, while 2 ovaries. Direct sequencing demonstrated that all SRY genes were normal in the patients positive for SRY genes. FISH technique demonstrated that SRY genes translocated from Ypter to Xpter in 2 46,XX phenotypic males positive for SRY genes. It was concluded that SRY gene is strongly involved in male sex determination, while a sequence of other genes may be taken into account in sexual development.