XX sex reversal, palmoplantar keratoderma, and predisposition to squamous cell carcinoma: Genetic analysis in one family

Dermatologic care of patients with differences of sex development

Background

Differences of sex development (DSD or disorders of sex development) are uncommon congenital conditions, characterized by atypical development of chromosomal, gonadal, or anatomic sex.

Objective

Dermatologic care is an important component of the multidisciplinary care needed for individuals with DSD. This article discusses the most common primary dermatologic manifestations of DSD in addition to the cutaneous manifestations of hormonal and surgical therapies in individuals with DSD.

Data sources

Published articles including case series and case reports on PubMed.

Study selections

Selection was conducted by examining existing literature with a team of multidisciplinary specialists.

Methods

Narrative review.

Limitations

This article was not conducted as a systematic review.

Results

In Klinefelter syndrome, refractory leg ulcers and incontinentia pigmenti have been described. Turner syndrome is associated with lymphatic malformations, halo nevi, dermatitis, and psoriasis. Virilization can be seen in some forms of congenital adrenal hyperplasia, where acne and hirsutism are common.

Conclusion

Dermatologists should consider teratogenic risk for treatments of skin conditions in DSD depending on pregnancy potential. Testosterone replacement, commonly used for Klinefelter syndrome, androgen insensitivity syndrome, 5-alpha reductase deficiency, gonadal dysgenesis, or ovotesticular DSD, may cause acne.

RSPO1-mutated keratinocytes from palmoplantar keratoderma display impaired differentiation, alteration of cell-cell adhesion, EMT-like phenotype and invasiveness properties: implications for squamous cell carcinoma susceptibility in patients with 46XX disorder of sexual development

Background

Secreted R-spondin (RSPO) proteins play a key role in reproductive organ development, epithelial stem cell renewal and cancer induction by reinforcing canonical Wnt signaling. We have previously reported that palmoplantar keratoderma (PPK), predisposition to cutaneous squamous cell carcinoma (SCC) development and sex reversal segregate as autosomal recessive trait in patients carrying RSPO1-mutations.

Although our previous findings suggested that RSPO1 secreted from fibroblasts regulates keratinocyte growth or differentiation, the role of this protein in the epidermis remains largely unexplored. Our study was aimed at expanding the phenotypic, molecular and functional characterization of RSPO1-mutated skin and keratinocytes.

Results

Cultured primary keratinocytes from PPK skin of a RSPO1-mutated XX-sex reversed patient displayed highly impaired differentiation and epithelial-mesenchymal transition (EMT)-like phenotype. Interestingly, RSPO1-mutated PPK skin expressed markers of increased proliferation, dedifferentiation and altered cell–cell adhesion. Furthermore, all these signs were more evident in SCC specimens of the patient. Cultured PPK patient’s keratinocytes exhibited increased expression of cell‒matrix adhesion proteins and extracellular matrix remodeling enzymes. Moreover, they showed invasiveness properties in an organotypic skin model in presence of PPK fibroblasts, which behave like cancer-associated fibroblasts. However, the co-culture with normal fibroblasts or treatment with the recombinant RSPO1 protein did not revert or reduce the EMT-like phenotype and invasion capability of PPK keratinocytes. Notably, RSPO1-mutated PPK fibroblasts induced a hyperproliferative and dedifferentiated phenotype of age-matched normal control plantar keratinocytes. Wnt signaling has a key role in both PPK promotion and SCC development. Accordingly, Wnt mediators were differentially expressed in both PPK keratinocytes and skin specimens of RSPO1-mutated patient compared to control.

Conclusions

Altogether our data indicate that the absence of RSPO1 in patients with 46XX disorder of sexual development affects the skin microenvironment and epidermal integrity, thus contributing to the risk of SCC tumorigenesis in palmoplantar regions exposed to major frictional stresses.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02434-2.

Screening for structural variants of four candidate genes in dogs with disorders of sex development revealed the first case of a large deletion in NR5A1

Disorders of sex development (DSD) are important causes of infertility and sterility, and are risk factors for gonadal carcinogenesis. Many DSDs are caused by genetic factors, mainly sex chromosome abnormalities or mutations of genes involved in sexual development, as well as structural variants (SVs) - large deletions, duplications, and insertions, if these overlap genes involved in sex development. The aim of this study was to determine if there were SVs in four candidate genes - NR0B1 (DAX1), NR5A1, RSPO1, and SOX3 - using droplet digital PCR (ddPCR). There was study of two cohorts of dogs with DSD, including 55 animals with XX DSD and 15 with XY DSD. In addition, 40 control females and 10 control males were included in the study. Among cases, for which there were evaluations, a large deletion consisting of four exons of the NR5A1 gene was identified in a Yorkshire Terrier with a rudimentary penis, hypospadias, bilateral cryptorchidism, and spermatogenesis inactive testes. This is the first mutation in the NR5A1 gene leading to XY DSD phenotype to be reported in domestic animals. There were no SVs in the genes evaluated in the present study in the cohort of dogs with XX DSD. The results from this study provide evidence that the large structural variants of these genes are rarely associated with the DSD phenotype in dogs.

Molecular Characterization of XX Maleness

Androgens and anti-Müllerian hormone (AMH), secreted by the foetal testis, are responsible for the development of male reproductive organs and the regression of female anlagen. Virilization of the reproductive tract in association with the absence of Müllerian derivatives in the XX foetus implies the existence of testicular tissue, which can occur in the presence or absence of SRY. Recent advancement in the knowledge of the opposing gene cascades driving to the differentiation of the gonadal ridge into testes or ovaries during early foetal development has provided insight into the molecular explanation of XX maleness.

Novel RSPO1 mutation causing 46,XX testicular disorder of sex development with palmoplantar keratoderma: A review of literature and expansion of clinical phenotype

Palmoplantar hyperkeratosis with squamous cell carcinoma of skin and sex reversal (MIM # 610644) is a clinically distinctive form of SRY-negative 46,XX disorder of sex development. It is a rare autosomal recessive disorder caused due to biallelic loss of function mutations in RSPO1 gene. RSPO1 acts by activating the canonical β-catenin pathway and is one of the most important genes controlling female gonadal differentiation. RSPO1-associated disorders of sex development have been described only in three instances in the past. We report fourth such case with additional findings and perform a comparative review of previous phenotypic descriptions, thereby expanding the clinical phenotype of this syndrome.

Interstitial microdeletion of the 1p34.3p34.2 region

BACKGROUND

Interstitial microdeletions of chromosome 1p34.3p34.2 are rare, but are continuing to be identified by the use of chromosome microarray. There have been fewer than 10 individuals identified who have deletions of the 1p34.3p34.2 region; all of these previously described individuals have deletions of the AGO1, AGO3, GRIK3, SLC2A1, or RIMS3 genes. Haploinsufficiency of these genes has been associated with neurodevelopmental delays.

METHODS

Chromosome microarray, quantitative PCR, and fluorescence in situ hybridization were performed with DNA extracted from peripheral blood.

RESULTS

Chromosome microarray identified a 2.3 Mb 1p34.3p34.2 one copy deletion in our patient with global developmental delay, mild intellectual disability, delayed bone age, bilateral vesicoureteral reflux, vocal cord paralysis, right aberrant subclavian artery, kyphoscoliosis, bilateral metatarsus adductus, and valgus knee deformity. This deletion was confirmed by quantitative PCR and does not include the AGO1, AGO3, GRIK3, SLC2A1, or RIMS3 genes. Subsequent FISH testing of the parents was negative.

CONCLUSION

Haploinsufficiency of the 1p34.3p34.2 region, including the SNIP1 gene and excluding the five genes listed above, is responsible for the neurocognitive delays and other symptoms as identified in our patient.

Involvement of FOXL2 and RSPO1 in Ovarian Determination, Development, and Maintenance in Mammals

In mammals, sex determination is a process through which the gonad is committed to differentiate into a testis or an ovary. This process relies on a delicate balance between genetic pathways that promote one fate and inhibit the other. Once the gonad is committed to the female pathway, ovarian differentiation begins and, depending on the species, is completed during gestation or shortly after birth. During this step, granulosa cell precursors, steroidogenic cells, and primordial germ cells start to express female-specific markers in a sex-dimorphic manner. The germ cells then arrest at prophase I of meiosis and, together with somatic cells, assemble into functional structures. This organization gives the ovary its definitive morphology and functionality during folliculogenesis. Until now, 2 main genetic cascades have been shown to be involved in female sex differentiation. The first is driven by FOXL2, a transcription factor that also plays a crucial role in folliculogenesis and ovarian fate maintenance in adults. The other operates through the WNT/CTNNB1 canonical pathway and is regulated primarily by R-spondin1. Here, we discuss the roles of FOXL2 and RSPO1/WNT/ CTNNB1 during ovarian development and homeostasis in different models, such as humans, goats, and rodents.

A mutation in the nucleoporin-107 gene causes XX gonadal dysgenesis

Ovarian development and maintenance are poorly understood; however, diseases that affect these processes can offer insights into the underlying mechanisms. XX female gonadal dysgenesis (XX-GD) is a rare, genetically heterogeneous disorder that is characterized by underdeveloped, dysfunctional ovaries, with subsequent lack of spontaneous pubertal development, primary amenorrhea, uterine hypoplasia, and hypergonadotropic hypogonadism. Here, we report an extended consanguineous family of Palestinian origin, in which 4 females exhibited XX-GD. Using homozygosity mapping and whole-exome sequencing, we identified a recessive missense mutation in nucleoporin-107 (NUP107, c.1339G>A, p.D447N). This mutation segregated with the XX-GD phenotype and was not present in available databases or in 150 healthy ethnically matched controls. NUP107 is a component of the nuclear pore complex, and the NUP107-associated protein SEH1 is required for oogenesis in Drosophila. In Drosophila, Nup107 knockdown in somatic gonadal cells resulted in female sterility, whereas males were fully fertile. Transgenic rescue of Drosophila females bearing the Nup107D364N mutation, which corresponds to the human NUP107 (p.D447N), resulted in almost complete sterility, with a marked reduction in progeny, morphologically aberrant eggshells, and disintegrating egg chambers, indicating defective oogenesis. These results indicate a pivotal role for NUP107 in ovarian development and suggest that nucleoporin defects may play a role in milder and more common conditions such as premature ovarian failure.

Molecular mechanisms of sexual development

Gonadal cellular organization is very similar in all vertebrates, though different processes can trigger bipotential gonads to develop into either testes or ovaries. While mammals and birds, apart from some exceptions, show genetic sex determination (GSD), other animals, like turtles and crocodiles, express temperature-dependent sex determination. In some groups of animals, GSD can also be overridden by hormone or temperature influences, indicating how fragile this system can be. This review aims to explain the fundamental molecular mechanisms involved in mammalian GSD, mainly referring to mouse as a major model. Conceivably, other mammals might show a molecular mechanism different from the commonly investigated murine species.

Syndromic true hermaphroditism due to an R-spondin1 (RSPO1) homozygous mutation

XX true hermaphroditism, also know as ovotesticular disorder of sexual development (DSD), is a disorder of gonadal development characterized by the presence of both ovarian and testicular tissue in a 46,XX individual. The genetic basis for XX true hermaphroditism and sex reversal syndromes unrelated to SRY translocation is still mostly unclear. We report mutational analysis of the RSPO1 gene in a 46,XX woman with true hermaphroditism, palmoplantar keratoderma, congenital bilateral corneal opacities, onychodystrophy, and hearing impairment. R-spondin1 is a member of the R-spondin protein family and its pivotal role in sex determination has been recently described. We identified a homozygous splice-donor-site mutation in the RSPO1 gene in our patient. We found that the c.286+1G>A mutation led to an aberrantly spliced mRNA (r.95_286del), which is presumably translated into a partially functional protein (p.Ile32_Ile95del). Our case demonstrates for the first time, to our knowledge, that XX true hermaphroditism can be caused by a single gene mutation. The reported findings represent a further step toward a complete understanding of the complex mechanisms leading to DSDs.

Linkage to CFA29 Detected in a Genome-Wide Linkage Screen of a Canine Pedigree Segregating Sry-Negative XX Sex Reversal

Canine Sry-negative XX sex reversal is a disorder of gonadal development wherein individuals having a female karyotype develop testes or ovotestes. In this study, linkage mapping was undertaken in a pedigree derived from one proven carrier American cocker spaniel founder male and beagle females. All affected dogs in the analysis were XX true hermaphrodites and confirmed to be Sry negative by polymerase chain reaction. A genome-wide linkage screen conducted using 245 microsatellite markers revealed highest LOD score of 3.4 (marker CPH9) on CFA29. Fine mapping with additional microsatellites in the region containing CPH9 localized the Sry-negative XX sex reversal locus to a 5.4-Mb candidate region between markers CPH9 and FH3003 (LOD score 3.15). Insignificant LOD scores were found at genome-wide screen or fine mapping markers that were within 10 Mb of 45 potential candidate genes reported to have a role in mammalian sex determination or differentiation. Together, these results suggest that a novel locus on CFA29 may be responsible for sex reversal in this pedigree.

Identification and molecular modelling of a novel familial mutation in the SRY gene implicated in the pure gonadal dysgenesis

SRY gene is responsible for initiating male sexual differentiation. The protein encoded by SRY contains a homeobox (HMG) domain, which is a DNA-binding domain. Mutations of the SRY gene are reported to be associated with XY pure gonadal dysgenesis. The majority of these are de novo mutations affecting only one individual in a family. Only a small subset of mutations is shared between the father and one or more of his children. Most of these familial mutations are localized within the HMG box and only two are at the N-terminal domain of the SRY protein. Herein, we describe a young girl with pure gonadal dysgenesis and her father carrying a novel familial mutation in the SRY gene at codon number 3. This mutation is resulting in a serine (S) to leucine (L) substitution. The secondary structure of the SRY protein was carried out by protein modelling studies. This analysis suggests, with high possibility, that the N-terminal domain of the SRY protein, where we found the mutation, could form an alpha-helix from amino acid in position 2 to amino acid in position 13. The secondary structure prediction and the chemical properties of serine to leucine substitution stands for a potential disruption of this N-terminal alpha-helix in the SRY protein. This mutation could have some role in impeding the normal function of the SRY protein.

R-spondin1 is essential in sex determination, skin differentiation and malignancy

R-spondins are a recently characterized small family of growth factors. Here we show that human R-spondin1 (RSPO1) is the gene disrupted in a recessive syndrome characterized by XX sex reversal, palmoplantar hyperkeratosis and predisposition to squamous cell carcinoma of the skin. Our data show, for the first time, that disruption of a single gene can lead to complete female-to-male sex reversal in the absence of the testis-determining gene, SRY.

Determination and stability of sex

How is the embryonic bipotential gonad regulated to produce either an ovary or a testis? In males, transient early activation of the Y chromosome Sry gene makes both germ cells and soma male. However, in females, available evidence suggests that the process of ovary sex determination may take place independently in the germline and somatic lineages. In addition, in contrast to testis, in ovary somatic cells, female-to-male gonadal sex reversal can occur at times throughout ovary development and maturation. We suggest that a single gene pathway, likely hinging on the Foxl2 transcription factor, both initiates and maintains sex differentiation in somatic cells of the mammalian ovary.