SEC31A may be associated with pituitary hormone deficiency and gonadal dysgenesis.

PURPOSE: Disorders/differences of sex development (DSD) result from variants in many different human genes but, frequently, have no detectable molecular cause. METHODS: Detailed clinical and genetic phenotyping was conducted on a family with three children. A Sec31a animal model and functional studies were used to investigate the significance of the findings. RESULTS: By trio whole-exome DNA sequencing we detected a heterozygous de novo nonsense SEC31A variant, in three children of healthy non-consanguineous parents. The children had different combinations of disorders that included complete gonadal dysgenesis and multiple pituitary hormone deficiency. SEC31A encodes a component of the COPII coat protein complex, necessary for intracellular anterograde vesicle-mediated transport between the endoplasmic reticulum (ER) and Golgi. CRISPR-Cas9 targeted knockout of the orthologous Sec31a gene region resulted in early embryonic lethality in homozygous mice. mRNA expression of ER-stress genes ATF4 and CHOP was increased in the children, suggesting defective protein transport. The pLI score of the gene, from gnomAD data, is 0.02. CONCLUSIONS: SEC31A might underlie a previously unrecognised clinical syndrome comprising gonadal dysgenesis, multiple pituitary hormone deficiencies, dysmorphic features and developmental delay. However, a variant that remains undetected, in a different gene, may alternatively be causal in this family.

Environmental oestrogens disrupt testicular descent and damage male reproductive health: Mechanistic insight.

Environmental oestrogens (EEs) as environmental pollutants have been paid much attention due to their impact on congenital malformation of male genitourinary system. Exposure to EEs for prolonged time could hinder testicular descent and cause testicular dysgenesis syndrome. Therefore, it is urgent to understand the mechanisms by which EEs exposure disrupt testicular descent. In this review, we summarize recent advances in our understanding of the process of testicular descent, which is regulated by intricate cellular and molecular networks. Increasing numbers of the components of these networks such as CSL and INSL3 are being identified, highlighting that testicular descent is a highly orchestrated process that is essential to human reproduction and survival. The exposure to EEs would lead to the imbalanced regulation of the networks and cause testicular dysgenesis syndrome such as cryptorchidism, hypospadias, hypogonadism, poor semen quality and testicular cancer. Fortunately, the identification of the components of these networks provides us the opportunity to prevent and treat EEs induced male reproductive dysfunction. The pathways that play an important role in the regulation of testicular descent are promising targets for the treatment of testicular dysgenesis syndrome.

Mutation analysis of WNT4 gene in SRY negative 46,XX DSD patients with Mullerian agenesis and/or gonadal dysgenesis- An Indian study.

Developmental disruption of the Mullerian duct and gonads in females leads to Mullerian agenesis and gonadal dysgenesis, respectively. These two structural abnormalities are coming under the 46,XX DSD (Disorders of Sexual Development) classification, the majority of cases the aetiology remains elusive. Without the SRY gene, WNT4 plays a key role in female reproductive structure development. Since there are no studies that explored the involvement of the WNT4 gene in Indian 46,XX DSD patients, we analysed the role of WNT4 in Indian 46,XX DSD patients with Mullerian agenesis and/or Gonadal dysgenesis. In our study, we recruited 103 adolescent girls with primary amenorrhea. After the cytogenetic and SRY gene analysis, we included thirty-two 46,XX DSD patients with Mullerian agenesis and/or gonadal dysgenesis for WNT4 gene mutation analysis. PCR sequencing was performed for all the coding exons of the WNT4 gene. Bioinformatic tools like Mutation Taster, Human Splicing Finder, and miRDB were used. We observed single nucleotide variations in three patients. One patient showed a known synonymous polymorphism (c.861C > T; p.G287G, rs544988174). miRDB data revealed the absence of microRNA regulatory sites in this region. The other two cases carried a nucleotide substitution in intronic regions and did not affect the normal splicing mechanism. In conclusion, we could not find any indication about WNT4 involvement in the disease condition. In the future, WNT4 promoter analysis in these patients and molecular characterization of the WNT4 coding and promoter region in more patients are needed to link WNT4 variants with these structural abnormalities.

Environmental Impacts on Male Reproductive Development: Lessons from Experimental Models.

BACKGROUND: Male reproductive development in mammals can be divided into a gonadal formation phase followed by a hormone-driven differentiation phase. Failure of these processes may result in Differences in Sex Development (DSD), which may include abnormalities of the male reproductive tract, including cryptorchidism, hypospadias, infertility, and testicular germ cell cancer (TGCC). These disorders are also considered to be part of a testicular dysgenesis syndrome (TDS) in males. Whilst DSDs are considered to result primarily from genetic abnormalities, the development of TDS disorders is frequently associated with environmental factors. SUMMARY: In this review, we will discuss the development of the male reproductive system in relation to DSD and TDS. We will also describe the experimental systems, including studies involving animals and human tissues or cells that can be used to investigate the role of environmental factors in inducing male reproductive disorders. We will discuss recent studies investigating the impact of environmental chemicals (e.g., phthalates and bisphenols), lifestyle factors (e.g., smoking) and pharmaceuticals (e.g., analgesics) on foetal testis development. Finally, we will describe the evidence, involving experimental and epidemiologic approaches, for a role of environmental factors in the development of specific male reproductive disorders, including cryptorchidism, hypospadias, and TGCC. KEY MESSAGES: Environmental exposures can impact the development and function of the male reproductive system in humans. Epidemiology studies and experimental approaches using human tissues are important to translate findings from animal studies and account for species differences in response to environmental exposures.

Effects of genomic instability in populations of Drosophila melanogaster from regions of Ukraine with different impact of radiation factors.

PURPOSE: To investigate differences in the gonadal dysgenesis frequency as one of the indicators of genome instability through natural populations of Drosophіla melanogaster, selected from Ukrainian regions with different radiation impacts. Follow-up study of the dynamics of this indicator under chronic exposure in laboratory conditions for 10 generations. MATERIALS AND METHODS: The study was conducted in two stages. The first one included trapping of insects in regions with different radiation loads with subsequent assessment of both the time of maturation and the index of the gonadal dysgenesis through the first (F1) generation, obtained in laboratory conditions. At the second stage, the dynamics of this indicator were investigated for the F1-descendants of each ten consequent generations, which were developed under laboratory conditions both with and without additional gamma-exposure with different characteristics of the dose rate 1.2 × 10-8, 0.3 × 10-8 and 0.12 × 10-8 Gy/sec. RESULTS: Differences in the gonadal dysgenesis frequency as one of the indicators of genome instability were revealed in F1-descendants of natural populations of Drosophіla melanogaster, selected from regions of different radiation impact. Under conditions of additional low rate chronic irradiation in laboratory conditions for 10 generations, significant differences in changes in the level and dynamics of this indicator were established depending on the accumulated dose of Drosophila populations from the city of Netishyn (Khmelnytskyi NPP) and Magarach city. There were no signs of adaptation. CONCLUSIONS: The discrepancy between the real and expected biological effects has reflected the difference in the intensity of the radiation background, which was traditionally determined by the gamma-emitters and did not take into account the wide range of other genotoxic elements from nuclear power emissions. A complex, non-monotonic type of frequency dynamics of gonadal dysgenesis could be determined by the interaction of radiation damage, protection and recovery.

Developmental exposure to real-life environmental chemical mixture programs a testicular dysgenesis syndrome-like phenotype in prepubertal lambs.

Current declines in male reproductive health may, in part, be driven by anthropogenic environmental chemical (EC) exposure. Using a biosolids treated pasture (BTP) sheep model, this study examined the effects of gestational exposure to a translationally relevant EC mixture. Testes of 8-week-old ram lambs from mothers exposed to BTP during pregnancy contained fewer germ cells and had a greater proportion of Sertoli-cell-only seminiferous tubules. This concurs with previous published data from fetuses and neonatal lambs from mothers exposed to BTP. Comparison between the testicular transcriptome of biosolids lambs and human testicular dysgenesis syndrome (TDS) patients indicated common changes in genes involved in apoptotic and mTOR signalling. Gene expression data and immunohistochemistry indicated increased HIF1α activation and nuclear localisation in Leydig cells of BTP exposed animals. As HIF1α is reported to disrupt testosterone synthesis, these results provide a potential mechanism for the pathogenesis of this testicular phenotype, and TDS in humans.

Pathogenic Variants in MAP3K1 Cause 46,XY Gonadal Dysgenesis: A Review.

Pathogenic variants in the MAP3K1 gene are an important cause of 46,XY non-syndromic partial and complete gonadal dysgenesis, accounting for at least 4% of cases. Inheritance occurs in a sex-limited, autosomal dominant fashion with virtually complete penetrance in 46,XY individuals. 46,XX carriers appear to have normal fertility and no developmental abnormalities. Pathogenic variants occur almost exclusively within known domains of the MAP3K1 protein, facilitating annotation when identified. Where studied, these variants have been modeled to alter the local MAP3K1 folding and surface domains and have been shown to alter interactions with known binding partners. The net effect of these variants is to increase phosphorylation of downstream targets ERK1, ERK2, and p38, resulting in multiple gain-of-function effects interfering with testis determination and enabling ovarian determination.

WT1 complete gonadal dysgenesis with membranoproliferative glomerulonephritis: case series and literature review.

BACKGROUND: Intronic WT1 mutations are usually causative of Frasier syndrome with focal segmental glomerulosclerosis as the characteristic nephropathy. Membranoproliferative glomerulonephritis is not commonly associated with disorders of sex development but has been recently identified as a WT1-associated nephropathy, but usually in cases of exonic mutations in either isolated Wilms tumor or Denys-Drash syndrome. METHODS: The clinical and genetic data from 3 individuals are reported. RESULTS: This report describes the kidney manifestations in 3 individuals from 2 unrelated families with Frasier syndrome intronic WT1 mutations, noting that 2 of the 3 individuals have histologically confirmed membranoproliferative glomerulonephritis. CONCLUSIONS: These case reports support expansion of the clinical spectrum of the kidney phenotypes associated with Frasier syndrome providing evidence of an association between WT1 mutation and an immune complex-related membranoproliferative glomerulonephritis. A higher resolution version of the Graphical abstract is available as Supplementary information.

Bilateral Ovarian Germ Cell Tumor in a 46,XX Female with Nijmegen Breakage Syndrome and Hypergonadotropic Hypogonadism

Nijmegen breakage syndrome (NBS) is a rare autosomal recessive disease, affecting mainly patients of Slavic origin. It is caused by a defect in the NBN gene, resulting in defective nibrin protein formation. This leads to chromosomal instability, which predisposes to cancer, with lymphoid malignancies predominating. Nibrin is also involved in gonadal development and its disfunction in females with NBS frequently results in a pure gonadal dysgenesis (PGD) causing hypergonadotropic hypogonadism. However, only a few ovarian tumors in NBS patients have been reported to date. We describe the first case of a girl with NBS with PGD, who developed metachronous bilateral ovarian germ cell tumors (dysgerminoma and gonadoblastoma). Pathogenesis of PGD, neoplastic transformation and therapeutic approach in females with NBS are discussed.

Revisiting the hybridization processes in the Triatoma brasiliensis complex (Hemiptera, Triatominae): Interspecific genomic compatibility point to a possible recent diversification of the species grouped in this monophyletic complex.

Triatomines are hematophagous insects of great epidemiological importance, since they are vectors of the protozoan Trypanosoma cruzi, the etiological agent of Chagas disease. Triatoma brasiliensis complex is a monophyletic group formed by two subspecies and six species: T. b. brasiliensis, T. b. macromelasoma, T. bahiensis, T. juazeirensis, T. lenti, T. melanica, T. petrocchiae and T. sherlocki. The specific status of several species grouped in the T. brasiliensis complex was confirmed from experimental crossing and analysis of reproductive barriers. Thus, we perform interspecific experimental crosses between T. lenti and other species and subspecies of the T. brasiliensis complex and perform morphological analysis of the gonads and cytogenetic analysis in the homeologous chromosomes of the hybrids of first generation (F1). Besides that, we rescue all the literature data associated with the study of reproductive barriers in this monophyletic complex of species and subspecies. For all crosses performed between T. b. brasiliensis, T. b. macromelasoma, T. juazeirensis and T. melanica with T. lenti, interspecific copulas occurred (showing absence of mechanical isolation), hybrids were obtained, none of the male hybrids presented the phenomenon of gonadal dysgenesis and 100% pairing between the chromosomes homeologous of the hybrids was observed. Thus, we demonstrate that there are no pre-zygotic reproductive barriers installed between T. lenti and the species and subspecies of the T. brasiliensis complex. In addition, we demonstrate that the hybrids obtained between these crosses have high genomic compatibility and the absence of gonadal dysgenesis. These results point to reproductive compatibility between T. lenti and species and subspecies of the T. brasiliensis complex (confirming its inclusion in the complex) and lead us to suggest a possible recent diversification of the taxa of this monophyletic group.

Analysis of the genomic landscape of yolk sac tumors reveals mechanisms of evolution and chemoresistance.

Yolk sac tumors (YSTs) are a major histological subtype of malignant ovarian germ cell tumors with a relatively poor prognosis. The molecular basis of this disease has not been thoroughly characterized at the genomic level. Here we perform whole-exome and RNA sequencing on 41 clinical tumor samples from 30 YST patients, with distinct responses to cisplatin-based chemotherapy. We show that microsatellite instability status and mutational signatures are informative of chemoresistance. We identify somatic driver candidates, including significantly mutated genes KRAS and KIT and copy-number alteration drivers, including deleted ARID1A and PARK2, and amplified ZNF217, CDKN1B, and KRAS. YSTs have very infrequent TP53 mutations, whereas the tumors from patients with abnormal gonadal development contain both KRAS and TP53 mutations. We further reveal a role of OVOL2 overexpression in YST resistance to cisplatin. This study lays a critical foundation for understanding key molecular aberrations in YSTs and developing related therapeutic strategies.

A fish with no sex: gonadal and adrenal functions partition between zebrafish NR5A1 co-orthologs.

People with NR5A1 mutations experience testicular dysgenesis, ovotestes, or adrenal insufficiency, but we do not completely understand the origin of this phenotypic diversity. NR5A1 is expressed in gonadal soma precursor cells before expression of the sex-determining gene SRY. Many fish have two co-orthologs of NR5A1 that likely partitioned ancestral gene subfunctions between them. To explore ancestral roles of NR5A1, we knocked out nr5a1a and nr5a1b in zebrafish. Single-cell RNA-seq identified nr5a1a-expressing cells that co-expressed genes for steroid biosynthesis and the chemokine receptor Cxcl12a in 1-day postfertilization (dpf) embryos, as does the mammalian adrenal-gonadal (interrenal-gonadal) primordium. In 2dpf embryos, nr5a1a was expressed stronger in the interrenal-gonadal primordium than in the early hypothalamus but nr5a1b showed the reverse. Adult Leydig cells expressed both ohnologs and granulosa cells expressed nr5a1a stronger than nr5a1b. Mutants for nr5a1a lacked the interrenal, formed incompletely differentiated testes, had no Leydig cells, and grew far larger than normal fish. Mutants for nr5a1b formed a disorganized interrenal and their gonads completely disappeared. All homozygous mutant genotypes lacked secondary sex characteristics, including male breeding tubercles and female sex papillae, and had exceedingly low levels of estradiol, 11-ketotestosterone, and cortisol. RNA-seq showed that at 21dpf, some animals were developing as females and others were not, independent of nr5a1 genotype. By 35dpf, all mutant genotypes greatly under-expressed ovary-biased genes. Because adult nr5a1a mutants form gonads but lack an interrenal and conversely, adult nr5a1b mutants lack a gonad but have an interrenal, the adrenal, and gonadal functions of the ancestral nr5a1 gene partitioned between ohnologs after the teleost genome duplication, likely owing to reciprocal loss of ancestral tissue-specific regulatory elements. Identifying such elements could provide hints to otherwise unexplained cases of Differences in Sex Development.

Mutations in the desert hedgehog (DHH) gene in the disorders of sexual differentiation and male infertility.

PURPOSE: To identify the contribution of mutations in the Desert Hedgehog (DHH) gene to the disorders of sexual differentiation (DSD) and male infertility. METHODS: The study included a total 430 subjects, including 47 gonadal dysgenesis cases, 6 patients with undescended testis and infertility characterized by azoospermia, 125 infertile male patients characterized by oligoasthenozoospermia, 24 patients with oligoasthenoteratozoospermia, and 200 ethnically matched normozoospermic fertile men who had fathered a child in the last two years. Sequencing of the complete coding region of the DHH gene was undertaken to find its contribution to the DSD and male infertility. RESULTS: We observed four novel mutations in the DHH gene in the cases with different reproductive anomalies. A synonymous substitution, c. 543C>T (p.His181His) was observed in 6.6% oligoasthenozoospermic infertile males and 1.5% normozoospermic fertile control samples (RR = 4.4077, 95%CI 1.19-16.29). Another synonymous substitution, c.990G>A (p.Ala330Ala) was observed in an infertile patient with unilateral undescended testis (case #12). Insertion of G at c.1156insG (p.Arg385fs) was observed in a case with bilateral undescended testis and azoospermia (case #23). In gonadal dysgenesis category, two mutations, insertion of G at c.1156insG (p.Arg385fs) and c.997A>G (p.Thr333Ala) substitution were observed in one case (case #34). These mutations were completely absent in control samples. CONCLUSION: Mutations in the DHH gene impact reproduction with mild mutations affecting fertility, and severe or multiple mutations resulting in gonadal dysgenesis.

The Potential Synergic Effect of a Complex Pattern of Multiple Inherited Genetic Variants as a Pathogenic Factor for Ovarian Dysgenesis: A Case Report.

Non-syndromic primary ovarian insufficiency due to ovarian dysgenesis in 46,XX patients is an uncommon finding in the general population, even though several monogenic variants have been reported as causative factors. Here, we describe a 15-year-old patient diagnosed with gonadal dysgenesis possibly due to the interaction of three potentially pathogenic variants of genes involved in ovarian maturation, namely factor in the germline alpha (FIGLA), newborn ovary homeobox-encoding (NOBOX) and nuclear receptor subfamily 5 group A member 1 (NR5A1). We also describe a different degree of residual ovarian function within the proband's family, whose female members carry one to three demonstrated variations in the aforementioned genes in a clinical spectrum potentially dependent on the number of alleles involved. Our results support the hypothesis that the severity of the clinical picture of the proband, resulting in complete ovarian dysgenesis, may be due to a synergic detrimental effect of inherited genetic variants.

Breast Cancer and Major Deviations of Genetic and Gender-related Structures and Function.

We have searched the literature for information on the risk of breast cancer (BC) in relation to gender, breast development, and gonadal function in the following 8 populations: 1) females with the Turner syndrome (45, XO); 2) females and males with congenital hypogonadotropic hypogonadism and the Kallmann syndrome; 3) pure gonadal dysgenesis (PGD) in genotypic and phenotypic females and genotypic males (Swyer syndrome); 4) males with the Klinefelter syndrome (47, XXY); 5) male-to-female transgender individuals; 6) female-to-male transgender individuals; 7) genotypic males, but phenotypic females with the complete androgen insensitivity syndrome, and 8) females with Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome (müllerian agenesis). Based on this search, we have drawn 3 major conclusions. First, the presence of a Y chromosome protects against the development of BC, even when female-size breasts and female-level estrogens are present. Second, without menstrual cycles, BC hardly occurs with an incidence comparable to males. There is a strong correlation between the lifetime number of menstrual cycles and the risk of BC. In our populations the BC risk in genetic females not exposed to progesterone (P4) is very low and comparable to males. Third, BC has been reported only once in genetic females with MRKH syndrome who have normal breasts and ovulating ovaries with normal levels of estrogens and P4. We hypothesize that the oncogenic glycoprotein WNT family member 4 is the link between the genetic cause of MRKH and the absence of BC women with MRKH syndrome.

The gene encoding the ketogenic enzyme HMGCS2 displays a unique expression during gonad development in mice.

Disorders/differences of sex development (DSD) cause profound psychological and reproductive consequences for the affected individuals, however, most are still unexplained at the molecular level. Here, we present a novel gene, 3-hydroxy-3-methylglutaryl coenzyme A synthase 2 (HMGCS2), encoding a metabolic enzyme in the liver important for energy production from fatty acids, that shows an unusual expression pattern in developing fetal mouse gonads. Shortly after gonadal sex determination it is up-regulated in the developing testes following a very similar spatial and temporal pattern as the male-determining gene Sry in Sertoli cells before switching to ovarian enriched expression. To test if Hmgcs2 is important for gonad development in mammals, we pursued two lines of investigations. Firstly, we generated Hmgcs2-null mice using CRISPR/Cas9 and found that these mice had gonads that developed normally even on a sensitized background. Secondly, we screened 46,XY DSD patients with gonadal dysgenesis and identified two unrelated patients with a deletion and a deleterious missense variant in HMGCS2 respectively. However, both variants were heterozygous, suggesting that HMGCS2 might not be the causative gene. Analysis of a larger number of patients in the future might shed more light into the possible association of HMGCS2 with human gonadal development.

Germ Cell Tumors in Dysgenetic Gonads.

This review describes the germ cell neoplasms that are malignant and most commonly associated with several types of gonadal dysgenesis. The most common neoplasm is gonadoblastoma, while others including dysgerminomas, yolk-sac tumors and teratomas are rare but can occur. The purpose of this review is to evaluate the incidences of these abnormalities and the circumstances surrounding these specific tumors.According to well-established methods, a PubMed systematic review was performed, to obtain relevant studies published in English and select those with the highest-quality data.Initially, the first search was performed using gonadal dysgenesis as the search term, resulting in 12,887 PubMed papers, published, from 1945 to 2017. A second search using ovarian germ cell tumors as the search term resulted in 10,473 papers, published from 1960 to 2017. Another search was performed in Medline, using germ cell neoplasia as the search term, and this search resulted in 7,560 papers that were published between 2003 to 2016, with 245 new papers assessing gonadoblastomas.The higher incidence of germ cell tumors in gonadal dysgenesis is associated with a chromosomal anomaly that leads to the absence of germ cells in these gonads and, consequently, a higher incidence of neoplasms when these tumors are located inside the abdomen. Several hypotheses suggest that increased incidence of germ cell tumors involves all or part of the Y chromosome or different genes.

Gene dosage of DAX-1, determining in sexual differentiation: duplication of DAX-1 in two sisters with gonadal dysgenesis.

Two sisters phenotypically normal females, presenting with tumor abdominal mass with histopathological findings of teratoma and gonadoblastoma associated to 46,XY male-to-female sex reversal syndrome, secondary to a duplication in DAX-1, possibly inherited of maternal gonadal mosaicism. Copy number variation and functional effects of the duplication were done by MLPA multiplex ligation-dependent probe amplification and real time PCR. DAX-1, also known as dosage sensitive sex reversal gene (DSS), is considered the most likely candidate gene involved in XY gonadal dysgenesis when overexpressed. The excess of DAX-1 gene disturbs testicular development by down regulation of SF-1, WT1, and SOX9. This is the first report of 46,XY sex reversal in two siblings who have a maternally inherited duplication of DAX-1 associated with reduced levels of expression of downstream genes as SOX9-SF1.

Germ cell tumors in dysgenetic gonads

This review describes the germ cell neoplasms that are malignant and most commonly associated with several types of gonadal dysgenesis. The most common neoplasm is gonadoblastoma, while others including dysgerminomas, yolk-sac tumors and teratomas are rare but can occur. The purpose of this review is to evaluate the incidences of these abnormalities and the circumstances surrounding these specific tumors. According to well-established methods, a PubMed systematic review was performed, to obtain relevant studies published in English and select those with the highest-quality data. Initially, the first search was performed using gonadal dysgenesis as the search term, resulting in 12,887 PubMed papers, published, from 1945 to 2017. A second search using ovarian germ cell tumors as the search term resulted in 10,473 papers, published from 1960 to 2017. Another search was performed in Medline, using germ cell neoplasia as the search term, and this search resulted in 7,560 papers that were published between 2003 to 2016, with 245 new papers assessing gonadoblastomas. The higher incidence of germ cell tumors in gonadal dysgenesis is associated with a chromosomal anomaly that leads to the absence of germ cells in these gonads and, consequently, a higher incidence of neoplasms when these tumors are located inside the abdomen. Several hypotheses suggest that increased incidence of germ cell tumors involves all or part of the Y chromosome or different genes.

GENETICS IN ENDOCRINOLOGY: Approaches to molecular genetic diagnosis in the management of differences/disorders of sex development (DSD): position paper of EU COST Action BM 1303 'DSDnet'

The differential diagnosis of differences or disorders of sex development (DSD) belongs to the most complex fields in medicine. It requires a multidisciplinary team conducting a synoptic and complementary approach consisting of thorough clinical, hormonal and genetic workups. This position paper of EU COST (European Cooperation in Science and Technology) Action BM1303 'DSDnet' was written by leading experts in the field and focuses on current best practice in genetic diagnosis in DSD patients. Ascertainment of the karyotpye defines one of the three major diagnostic DSD subclasses and is therefore the mandatory initial step. Subsequently, further analyses comprise molecular studies of monogenic DSD causes or analysis of copy number variations (CNV) or both. Panels of candidate genes provide rapid and reliable results. Whole exome and genome sequencing (WES and WGS) represent valuable methodological developments that are currently in the transition from basic science to clinical routine service in the field of DSD. However, in addition to covering known DSD candidate genes, WES and WGS help to identify novel genetic causes for DSD. Diagnostic interpretation must be performed with utmost caution and needs careful scientific validation in each DSD case.