46,XY complete gonadal dysgenesis in a familial case with a rare mutation in the desert hedgehog (DHH) gene

Genetic diagnosis of endocrine disorders in Cyprus through the Cyprus Institute of Neurology and Genetics: an ENDO-ERN Reference Center

The report covers the current and past activities of the department Molecular Genetics-Function and Therapy (MGFT) at the Cyprus Institute of Neurology and Genetics (CING), an affiliated Reference Center for the European Reference Network on Rare Endocrine Conditions (Endo-ERN).The presented data is the outcome of > 15 years long standing collaboration between MGFT and endocrine specialists from the local government hospitals and the private sector. Up-to-date > 2000 genetic tests have been performed for the diagnosis of inherited rare endocrine disorders. The major clinical entities included Congenital Adrenal Hyperplasia (CAH) due to pathogenic variants in CYP21A2 gene and Multiple Endocrine Neoplasia (MEN) type 2 due to pathogenic variants in the RET proto-oncogene. Other rare and novel pathogenic variants in ANOS1, WDR11, FGFR1, RNF216, and CHD7 genes were also found in patients with Congenital Hypogonadotropic Hypogonadism. Interestingly, a few patients with Disorders of Sexual Differentiation (DSD) shared rare pathogenic variants in the SRD5A2, HSD17B3 and HSD3B2 while patients with Glucose and Insulin Homeostasis carried theirs in GCK and HNF1A genes. Lastly, MGFT over the last few years has established an esteemed diagnostic and research program on premature puberty with emphasis on the implication of MKRN3 gene on the onset of the disease and the identification of other prognosis biomarkers.As an Endo-ERN member MGFT department belongs to this large European network and holds the same humanistic ideals which aim toward the improvements of health care for patients with rare endocrine conditions in respect to improved and faster diagnosis.

A Risk of Gonadoblastoma in Familial Swyer Syndrome-A Case Report and Literature Review

A complete gonadal dysgenesis (CGD) with 46,XY karyotype is known as the Swyer syndrome and belongs to the group of 46,XY differences of sex development (DSD). The main problem in patients with Swyer syndrome is the delayed puberty and primary amenorrhea. Moreover, intrabdominal dysgenetic gonads in the patient with genetic material of a Y chromosome may conduce to the development of gonadal tumors, such as gonadoblastoma or germinoma. The management of such patients is based on preventive excision of dysgenetic gonads and long-term hormonal replacement therapy. Sporadic cases are considered more common than familial cases. This paper presents two siblings with Swyer syndrome in whom gonadoblastoma was found. A thorough review of familial CGD with 46,XY DSD in the literature from the last 15 years suggests that the risk of gonadal tumors could be increased in familial compared to sporadic cases (66.6% vs. 15-45%, respectively).

New observations on minifascicular neuropathy with sex-dependent gonadal dysgenesis: a case series with nerve ultrasound assessment

BACKGROUND

Gonadal dysgenesis with minifascicular neuropathy (GDMN) is a rare autosomal recessive condition associated with biallelic DHH pathogenic variants. In 46, XY individuals, this disorder is characterized by an association of minifascicular neuropathy (MFN) and gonadal dysgenesis, while in 46, XX subjects only the neuropathic phenotype is present. Very few patients with GDMN have been reported so far. We describe four patients with MFN due to a novel DHH likely pathogenic homozygous variant and the results of nerve ultrasound assessment.

METHODS

This retrospective observational study included 4 individuals from 2 unrelated Brazilian families evaluated for severe peripheral neuropathy. Genetic diagnosis was performed with a peripheral neuropathy next-generation sequencing (NGS) panel based on whole exome sequencing focused analysis that included a control SRY probe to confirm genetic sex. Clinical characterization, nerve conduction velocity studies, and high-resolution ultrasound nerve evaluation were performed in all subjects.

RESULTS

Molecular analysis disclosed in all subjects the homozygous DHH variant p.(Leu335Pro). Patients had a striking phenotype, with marked trophic changes of extremities, sensory ataxia, and distal anesthesia due to a sensory-motor demyelinating polyneuropathy. One 46, XY phenotypically female individual had gonadal dysgenesis. High-resolution nerve ultrasound showed typical minifascicular formation and increased nerve area in at least one of the nerves assessed in all patients.

CONCLUSION

Gonadal dysgenesis with minifascicular neuropathy is a severe autosomal recessive neuropathy characterized by trophic alterations in limbs, sensory ataxia, and distal anesthesia. Nerve ultrasound studies are very suggestive of this condition and may help to avoid invasive nerve biopsies.

Case Report: Long-term follow-up of desert hedgehog variant caused 46, XY gonadal dysgenesis with multiple complications in a Chinese child

Background: Desert hedgehog (DHH), as a member of the Hedgehog (HH) family, is mainly involved in testicular development and peripheral nerve sheath formation. A DHH variant has been identified in patients with 46, XY gonadal dysgenesis (46, XY GD) with or without neuropathy, but few reports mention the involvement of other complications.

Case presentation: Here, we report a Chinese female patient who was hospitalized at 14.3 years old due to slow breast development for more than 1 year. She had a female genitalia phenotype and breast development started at 13 years old but progressed slowly. She was not yet menarche on admission, and she had intermittent muscle cramps in her hands and feet. Her karyotype analysis was 46, XY and the SRY gene was positive. Surgical exploration revealed no uterus or ovaries, and the pathology of bilateral gonads was dysplastic testis tissue, which was consistent with partial gonadal dysgenesis (PGD). Genetic analysis identified a homozygous pathogenic variant in DHH exon 3 (c.1027T>C, p. Cys343Arg). During the 6-year follow-up, she received estrogen replacement therapy, resulting in breast development progression without gender dysphoria. However, her peripheral neuropathy became more obvious, and a nerve conduction study (NCS) indicated decreased nerve conduction velocity and action potential. In addition, she also suffered complications such as obesity, insulin resistance, fatty liver, and gastric ulcers.

Conclusion: In the present study, we reported a case of 46, XY GD with minifascicular neuropathy caused by a DHH homozygous variant, and we summarized the reported cases worldwide. For the first time in such patients, we showed a comparison of NCS changes with age as well as the presence of multiple complications not previously reported.

The Desert Hedgehog Signalling Pathway in Human Gonadal Development and Differences of Sex Development

While the Hedgehog signalling pathway is implicated in numerous developmental processes and maladies, variants in the Desert Hedgehog (DHH) ligand underlie a condition characterised by 46,XY gonadal dysgenesis with or without peripheral neuropathy. We discuss here the role and regulation of DHH and its signalling pathway in the developing gonads and examine the current understanding of how disruption to this pathway causes this difference of sex development (DSD) in humans.

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.

Whole exome sequencing uncovered highly penetrant recessive mutations for a spectrum of rare genetic pediatric diseases in Bangladesh

Collectively, rare genetic diseases affect a significant number of individuals worldwide. In this study, we have conducted whole-exome sequencing (WES) and identified underlying pathogenic or likely pathogenic variants in five children with rare genetic diseases. We present evidence for disease-causing autosomal recessive variants in a range of disease-associated genes such as DHH-associated 46,XY gonadal dysgenesis (GD) or 46,XY sex reversal 7, GNPTAB-associated mucolipidosis II alpha/beta (ML II), BBS1-associated Bardet-Biedl Syndrome (BBS), SURF1-associated Leigh Syndrome (LS) and AP4B1-associated spastic paraplegia-47 (SPG47) in unrelated affected members from Bangladesh. Our analysis pipeline detected three homozygous mutations, including a novel c. 863 G > C (p.Pro288Arg) variant in DHH, and two compound heterozygous variants, including two novel variants: c.2972dupT (p.Met991Ilefs*) in GNPTAB and c.229 G > C (p.Gly77Arg) in SURF1. All mutations were validated by Sanger sequencing. Collectively, this study adds to the genetic heterogeneity of rare genetic diseases and is the first report elucidating the genetic profile of (consanguineous and nonconsanguineous) rare genetic diseases in the Bangladesh population.