A novel A10E homozygous mutation in the HSD3B2 gene causing severe salt-wasting 3beta-hydroxysteroid dehydrogenase deficiency in 46,XX and 46,XY French-Canadians: evaluation of gonadal function after puberty

Unexpectedly high mutation rate of cyp11b1 compared to cyp21a2 in randomly-selected turkish women: a large screening study

PURPOSE

Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders resulting from enzyme deficiencies associated with steroidogenesis. The clinical presentation of non-classic CAH (NCAH) in females is often indistinguishable from other hyperandrogenic disorders like polycystic ovary syndrome (PCOS). The data on the prevalence of NCAH in unselected women in the literature is scanty. The research aimed to evaluate the prevalence of NCAH, carrier frequencies, and the correlation between clinical symptoms and genotype in Turkish women.

METHODS

The study group comprised two hundred and seventy randomly-selected unrelated asymptomatic women of reproductive age (18-45). Subjects were recruited from female blood donors. All volunteers underwent clinical examination and hormone measurements. The protein-encoding exons and exon-intron boundaries of the CYP21A2, CYP11B1, HSD3β2 and CYP21A2 promoter were sequenced by direct DNA sequencing.

RESULTS

After genotyping, seven (2.2%) individuals were diagnosed with NCAH. The heterozygous carrier frequencies of CYP21A2, CYP21A2 promoter, CYP11B1, and HSD3β2 genes with 34, 34, 41, and 1 pathologic mutation were determined at 12.6%, 12.6%, 15.2%, and 0.37% of volunteers, respectively. Gene-conversion (GC) frequencies between CYP21A2/CYP21A1P and CYP11B1/CYP11B2 were determined as 10.4% and 14.8%, respectively.

CONCLUSION

Despite GC-derived higher mutation frequency determined in the CYP11B1 gene, the reason for the low frequency of NCAH due to 11OHD compared to 21OHD might be that gene-conversion arises with active CYP11B2 rather than an inactive pseudogene. HSD3β1 exhibits high homology with HSD3β2 located on the same chromosome; remarkably, it demonstrates low heterozygosity and no GC, most probably the outcome of a tissue-specific expression pattern.

Bioinformatics analysis and verification of hub genes in 46,XY, disorders of sexual development

CONTEXT

46,XY, disorders of sexual development (46,XY, DSD) is a congenital genetic disease whose pathogenesis is complex and clinical manifestations are diverse. The existing molecular research has often focused on single-centre sequencing data, instead of prediction based on big data.

AIMS

This work aimed to fully understand the pathogenesis of 46,XY, DSD, and summarise the key pathogenic genes.

METHODS

Firstly, the potential pathogenic genes were identified from public data. Secondly, bioinformatics was used to predict pathogenic genes, including hub gene analysis, protein-protein interaction (PPI) and function enrichment analysis. Lastly, the genomic DNA from two unrelated families were recruited, next-generation sequencing and Sanger sequencing were performed to verify the hub genes.

KEY RESULTS

A total of 161 potential pathogenic genes were selected from MGI and PubMed gene sets. The PPI network was built which included 144 nodes and 194 edges. MCODE 4 was selected from PPI which scored the most significant P -value. The top 15 hub genes were ranked and identified by Cytoscape. Furthermore, three variants were found on SRD5A2 gene by genome sequencing, which belonged to the prediction hub genes.

CONCLUSIONS

Our results indicate that occurrence of 46,XY, DSD is attributed to a variety of genes. Bioinformatics analysis can help us predict the hub genes and find the most core network MCODE model.

IMPLICATIONS

Bioinformatic predictions may provide a novel perspective on better understanding the pathogenesis of 46,XY, DSD.

Coexistence of Congenital Adrenal Hyperplasia and Autoimmune Addison's Disease

Background: Underlying causes of adrenal insufficiency include congenital adrenal hyperplasia (CAH) and autoimmune adrenocortical destruction leading to autoimmune Addison's disease (AAD). Here, we report a patient with a homozygous stop-gain mutation in 3β-hydroxysteroid dehydrogenase type 2 (3βHSD2), in addition to impaired steroidogenesis due to AAD. Case Report: Whole exome sequencing revealed an extremely rare homozygous nonsense mutation in exon 2 of the HSD3B2 gene, leading to a premature stop codon (NM_000198.3: c.15C>A, p.Cys5Ter) in a patient with AAD and premature ovarian insufficiency. Scrutiny of old medical records revealed that the patient was initially diagnosed with CAH with hyperandrogenism and severe salt-wasting shortly after birth. However, the current steroid profile show complete adrenal insufficiency including low production of pregnenolone, dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEA-S), without signs of overtreatment with steroids. Conclusion: To the best of our knowledge, this is the first description of autoimmune adrenalitis in a patient with 3βHSD2 deficiency and suggests a possible association between AAD and inborn errors of the steroidogenesis.

46,XX DSD due to Androgen Excess in Monogenic Disorders of Steroidogenesis: Genetic, Biochemical, and Clinical Features

The term 'differences of sex development' (DSD) refers to a group of congenital conditions that are associated with atypical development of chromosomal, gonadal, or anatomical sex. Disorders of steroidogenesis comprise autosomal recessive conditions that affect adrenal and gonadal enzymes and are responsible for some conditions of 46,XX DSD where hyperandrogenism interferes with chromosomal and gonadal sex development. Congenital adrenal hyperplasias (CAHs) are disorders of steroidogenesis that mainly involve the adrenals (21-hydroxylase and 11-hydroxylase deficiencies) and sometimes the gonads (3-beta-hydroxysteroidodehydrogenase and P450-oxidoreductase); in contrast, aromatase deficiency mainly involves the steroidogenetic activity of the gonads. This review describes the main genetic, biochemical, and clinical features that apply to the abovementioned conditions. The activities of the steroidogenetic enzymes are modulated by post-translational modifications and cofactors, particularly electron-donating redox partners. The incidences of the rare forms of CAH vary with ethnicity and geography. The elucidation of the precise roles of these enzymes and cofactors has been significantly facilitated by the identification of the genetic bases of rare disorders of steroidogenesis. Understanding steroidogenesis is important to our comprehension of differences in sexual development and other processes that are related to human reproduction and fertility, particularly those that involve androgen excess as consequence of their impairment.

Clinical perspectives in congenital adrenal hyperplasia due to 3β-hydroxysteroid dehydrogenase type 2 deficiency

PURPOSE

3β-hydroxysteroid dehydrogenase type 2 deficiency (3βHSD2D) is a very rare variant of congenital adrenal hyperplasia (CAH) causing less than 0.5% of all CAH. The aim was to review the literature.

METHODS

PubMed was searched for relevant articles.

RESULTS

3βHSD2D is caused by HSD3B2 gene mutations and characterized by impaired steroid synthesis in the gonads and the adrenal glands and subsequent increased dehydroepiandrosterone (DHEA) concentrations. The main hormonal changes observed in patients with 3βHSD2D are elevated ratios of the Δ5-steroids over Δ4-steroids but molecular genetic testing is recommended to confirm the diagnosis. Several deleterious mutations in the HSD3B2 gene have been associated with salt-wasting (SW) crisis in the neonatal period, while missense mutations have been associated with a non-SW phenotype. Boys may have ambiguous genitalia, whereas girls present with mild or no virilization at birth. The existence of non-classic 3βHSD2D is controversial. In an acute SW crisis, the treatment includes prompt rehydration, correction of hypoglycemia, and parenteral hydrocortisone. Similar to other forms of CAH, glucocorticoid and mineralocorticoid replacement is needed for long-term management. In addition, sex hormone replacement therapy may be required if normal progress through puberty is failing. Little is known regarding possible negative long-term consequences of 3βHSD2D and its treatments, e.g., fertility, final height, osteoporosis and fractures, adrenal and testicular tumor risk, and mortality.

CONCLUSION

Knowledge is mainly based on case reports but many long-term outcomes could be presumed to be similar to other types of CAH, mainly 21-hydroxylase deficiency, although in 3βHSD2D it seems to be more difficult to suppress the androgens.

Human 3beta-hydroxysteroid dehydrogenase deficiency associated with normal spermatic numeration despite a severe enzyme deficit

Human 3 beta-hydroxysteroid dehydrogenase deficiency (3b-HSD) is a very rare form of congenital adrenal hyperplasia resulting from HSD3B2 gene mutations. The estimated prevalence is less than 1/1,000,000 at birth. It leads to steroidogenesis impairment in both adrenals and gonads. Few data are available concerning adult testicular function in such patients. We had the opportunity to study gonadal axis and testicular function in a 46,XY adult patient, carrying a HSD3B2 mutation. He presented at birth a neonatal salt-wasting syndrome. He had a micropenis, a perineal hypospadias and two intrascrotal testes. HSD3B2 gene sequencing revealed a 687del27 homozygous mutation. The patient achieved normal puberty at the age of 15 years. Transition from the paediatric department occurred at the age of 19 years. His hormonal profile under hydrocortisone and fludrocortisone treatments revealed normal serum levels of 17OH-pregnenolone, as well as SDHEA, ACTH, total testosterone, inhibin B and AMH. Pelvic ultrasound identified two scrotal testes of 21 mL each, without any testicular adrenal rest tumours. His adult spermatic characteristics were normal, according to WHO 2010 criteria, with a sperm concentration of 57.6 million/mL (N > 15), 21% of typical forms (N > 4%). Sperm vitality was subnormal (41%; N > 58%). This patient, in contrast to previous reports, presents subnormal sperm parameters and therefore potential male fertility in a 24-years-old patient with severe 3b-HSD deficiency. This case should improve counselling about fertility of male patients carrying HSD3B2 mutation.

A New Homozygous Frameshift Mutation in the HSD3B2 Gene in an Apparently Nonconsanguineous Italian Family

BACKGROUND

3β-Hydroxysteroid dehydrogenase (3β-HSD) deficiency is a rare cause of congenital adrenal hyperplasia (CAH) caused by inactivating mutations in the HSD3B2 gene.

PATIENT AND METHODS

We report the molecular and structural analysis of the HSD3B2 gene in a 46,XY child born to apparently nonconsanguineous parents and presenting ambiguous genitalia and salt wasting. The steroid profile showed elevated concentrations of 17-hydroxyprogesterone, androstenedione, ACTH and plasma renin, but normal values of cortisol and dehydroepiandrosterone sulfate. Unexpectedly, plasma aldosterone was high. For structural and functional analyses, the three-dimensional structure of 3β-HSD2 was modeled using the crystal structure of the short-chain dehydrogenase Gox2253 from Gluconobacter oxydans as a template.

RESULTS

The direct DNA sequence of the child revealed a new homozygous frameshift mutation in exon 4 of the HSD3B2 gene, a single nucleotide deletion at codon 319 [GTC(Val)x2192;GC], yielding premature stop codon in position 367. Molecular homology modeling and secondary structure predictions suggested that the variant sequence might both alter the substrate-binding cleft and compromise the overall stability of the enzyme.

CONCLUSION

We have described the first HSD3B2 gene mutation in the Italian population and analyzed its effect in the context of the 3β-HSD2 structure and function.

Differential regulation of human 3β-hydroxysteroid dehydrogenase type 2 for steroid hormone biosynthesis by starvation and cyclic AMP stimulation: studies in the human adrenal NCI-H295R cell model

Human steroid biosynthesis depends on a specifically regulated cascade of enzymes including 3β-hydroxysteroid dehydrogenases (HSD3Bs). Type 2 HSD3B catalyzes the conversion of pregnenolone, 17α-hydroxypregnenolone and dehydroepiandrosterone to progesterone, 17α-hydroxyprogesterone and androstenedione in the human adrenal cortex and the gonads but the exact regulation of this enzyme is unknown. Therefore, specific downregulation of HSD3B2 at adrenarche around age 6–8 years and characteristic upregulation of HSD3B2 in the ovaries of women suffering from the polycystic ovary syndrome remain unexplained prompting us to study the regulation of HSD3B2 in adrenal NCI-H295R cells. Our studies confirm that the HSD3B2 promoter is regulated by transcription factors GATA, Nur77 and SF1/LRH1 in concert and that the NBRE/Nur77 site is crucial for hormonal stimulation with cAMP. In fact, these three transcription factors together were able to transactivate the HSD3B2 promoter in placental JEG3 cells which normally do not express HSD3B2. By contrast, epigenetic mechanisms such as methylation and acetylation seem not involved in controlling HSD3B2 expression. Cyclic AMP was found to exert differential effects on HSD3B2 when comparing short (acute) versus long-term (chronic) stimulation. Short cAMP stimulation inhibited HSD3B2 activity directly possibly due to regulation at co-factor or substrate level or posttranslational modification of the protein. Long cAMP stimulation attenuated HSD3B2 inhibition and increased HSD3B2 expression through transcriptional regulation. Although PKA and MAPK pathways are obvious candidates for possibly transmitting the cAMP signal to HSD3B2, our studies using PKA and MEK1/2 inhibitors revealed no such downstream signaling of cAMP. However, both signaling pathways were clearly regulating HSD3B2 expression.