New insight into the molecular basis of 3beta-hydroxysteroid dehydrogenase deficiency: identification of eight mutations in the HSD3B2 gene eleven patients from seven new families and comparison of the functional properties of twenty-five mutant enzymes

Evaluation of 3β-hydroxysteroid dehydrogenase activity using progesterone and androgen receptors-mediated transactivation

3β-Hydroxysteroid dehydrogenases (3β-HSDs) catalyze the oxidative conversion of delta (5)-ene-3-beta-hydroxy steroids and ketosteroids. Human 3β-HSD type 2 (HSD3B2) is predominantly expressed in gonadal and adrenal steroidogenic cells for producing all classes of active steroid hormones. Mutations in HSD3B2 gene cause a rare form of congenital adrenal hyperplasia with varying degree of salt wasting and incomplete masculinization, resulting from reduced production of corticoids and androgens. Therefore, evaluation of the HSD3B2 enzymatic activity in both pathways for each steroid hormone production is important for accurately understanding and diagnosing this disorder. Using progesterone receptor (PR)- and androgen receptor (AR)-mediated transactivation, we adapted a method that easily evaluates enzymatic activity of HSD3B2 by quantifying the conversion from substrates [pregnenolone (P5) and dehydroepiandrosterone (DHEA)] to (progesterone and androstenedione). HEK293 cells were transduced to express human HSD3B2, and incubated medium containing P5 or DHEA. Depending on the incubation time with HSD3B2-expressing cells, the culture media progressively increased luciferase activities in CV-1 cells, transfected with the PR/AR expression vector and progesterone-/androgen-responsive reporter. Culture media from human and other mammalian HSD3B1-expressing cells also increased the luciferase activities. HEK293 cells expressing various missense mutations in the HSD3B2 gene revealed the potential of this system to evaluate the relationship between the enzymatic activities of mutant proteins and patient phenotype.

Genotype, Mortality, Morbidity, and Outcomes of 3β-Hydroxysteroid Dehydrogenase Deficiency in Algeria

Background

3β-hydroxysteroid dehydrogenase 2 (3βHSD2) deficiency is a rare form of congenital adrenal hyperplasia (CAH), with fewer than 200 cases reported in the world literature and few data on outcomes.

Patients and Methods

We report a mixed longitudinal and cross-sectional study from a single Algerian center between 2007 and 2021. Virilization and under-masculinization were assessed using Prader staging and the external masculinization score (EMS), pubertal development staged according to the system of Tanner. Adrenal steroids were measured using mass spectrophotometry (LC-MS/MS). A genetic analysis of HSD3B2 was performed using Sanger sequencing.

Results

A 3βHSD2 defect was confirmed in 6 males and 8 females from 10 families (8 consanguineous), with p.Pro222Gln mutation in all but two siblings with a novel deletion: c.453_464del or p.(Thr152_Pro155del). Probable 3βHSD2 deficiency was diagnosed retrospectively in a further 6 siblings who died, and in two patients from two other centers. In the genetically confirmed patients, the median (range) age at presentation was 20 (0-390) days, with salt-wasting (n = 14) and genital anomaly (n = 10). The Prader stage for female patients was 2 (1-2) with no posterior fusion of the labia. The EMS for males was 6 (3-9). Median (range) values at diagnosis for 17-hydroxyprogesterone (17-OHP), dehydroepiandrosterone sulfate (DHEA-S), and 17-hydroxypregnenolone (17OHPreg) were elevated: 73.7 (0.37-164.3) nmol/L; 501.2(9.4-5441.3) nmol/L, and 139.7 (10.9-1500) nmol/l (NB >90 nmol/L diagnostic of 3βHSD2 defect). Premature pubarche was observed in four patients (3F:1M). Six patients (5F:1M) entered puberty spontaneously, aged 11 (5-13) years in 5 girls and 11.5 years in one boy. Testicular adrenal rest tumors were found in three boys. Four girls reached menarche at 14.3 (11-14.5) years, with three developing adrenal masses (surgically excised in two) and polycystic ovary syndrome (PCOS), with radiological evidence of ovarian adrenal rest tumor in one. The median IQ was 90 (43-105), >100 in only two patients and <70 in three.

Conclusions

The prevalence of 3βHSD2 deficiency in Algeria appears high, with p.Pro222Gln being the most frequent mutation. Mortality is also high, with significant morbidity from adrenal tumors and PCOS in adolescence and an increased risk of learning disability. The finding of adrenal tumors in older patients with 3βHSD2 indicates under-replacement, requiring effective hydrocortisone and fludrocortisone treatment rather than surgical removal.

Birth of a healthy boy following preimplantation genetic diagnosis for congenital adrenal hyperplasia

Classical 3β-HSD deficiency due to mutations in the HSD3B2 gene is responsible for a rare form of congenital adrenal hyperplasia (CAH) and is identified by varying degrees of salt wasting. Preimplantation genetic diagnosis (PGD) was performed in a couple carrying mutation c.690 G>A in the HSD3B2 gene. Four polymorphic short tandem repeat markers closely linked to the HSD3B2 gene (D1S185, D1S453, D1S514, D1S540) for linkage analysis in conjunction with the direct mutation analysis were used in embryo genotyping. Two CODIS STRs (VWA and THO1) were also used to confirm embryo zygosity and rule out possible contaminations. Finally, SRY and AMYLOGENIN markers were used for embryo sex determination. PGD was performed by fluorescent multiplex seminested polymerase chain reaction and sequencing. Six embryos were tested and one male carrier embryo was transferred, resulting in the birth of a healthy boy.

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.

Clinical and molecular review of atypical congenital adrenal hyperplasia

Congenital adrenal hyperplasia (CAH) is one of the most common inherited metabolic disorders. It comprises a group of autosomal recessive disorders caused by the mutations in the genes encoding for steroidogenic enzymes that involved cortisol synthesis. More than 90% of cases are caused by a defect in the enzyme 21-hydroxylase. Four other enzyme deficiencies (cholesterol side-chain cleavage, 17α-hydroxylase [P450c17], 11β-hydroxylase [P450c11β], 3β-hydroxysteroid dehydrogenase) in the steroid biosynthesis pathway, along with one cholesterol transport protein defect (steroidogenic acute regulatory protein), and one electrontransfer protein (P450 oxidoreductase) account for the remaining cases. The clinical symptoms of the different forms of CAH result from the particular hormones that are deficient and those that are produced in excess. A characteristic feature of CAH is genital ambiguity or disordered sex development, and most variants are associated with glucocorticoid deficiency. However, in the rare forms of CAH other than 21-hydroxylase deficiency so-called "atypical CAH", the clinical and hormonal phenotypes can be more complicated, and are not well recognized. This review will focus on the atypical forms of CAH, including the genetic analyses, and phenotypic correlates.

Adrenal androgens and androgen precursors-definition, synthesis, regulation and physiologic actions

The human adrenal produces more 19 carbon (C19) steroids, by mass, than either glucocorticoids or mineralocorticoids. However, the mechanisms regulating adrenal C19 steroid biosynthesis continue to represent one of the most intriguing mysteries of endocrine physiology. This review will discuss the C19 steroids synthesized by the human adrenal and the features within the adrenal that allow production of these steroids. Finally, we consider the effects of these steroids in normal physiology and disorders of adrenal C19 steroid excess.

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.

Salt-sensitive hypertension in circadian clock-deficient Cry-null mice involves dysregulated adrenal Hsd3b6

Malfunction of the circadian clock has been linked to the pathogenesis of a variety of diseases. We show that mice lacking the core clock components Cryptochrome-1 (Cry1) and Cryptochrome-2 (Cry2) (Cry-null mice) show salt-sensitive hypertension due to abnormally high synthesis of the mineralocorticoid aldosterone by the adrenal gland. An extensive search for the underlying cause led us to identify type VI 3beta-hydroxyl-steroid dehydrogenase (Hsd3b6) as a new hypertension risk factor in mice. Hsd3b6 is expressed exclusively in aldosterone-producing cells and is under transcriptional control of the circadian clock. In Cry-null mice, Hsd3b6 messenger RNA and protein levels are constitutively high, leading to a marked increase in 3beta-hydroxysteroid dehydrogenase-isomerase (3beta-HSD) enzymatic activity and, as a consequence, enhanced aldosterone production. These data place Hsd3b6 in a pivotal position through which circadian clock malfunction is coupled to the development of hypertension. Translation of these findings to humans will require clinical examination of human HSD3B1 gene, which we found to be functionally similar to mouse Hsd3b6.

Basic concepts and recent developments in human steroid hormone biosynthesis

The biosynthesis of steroid hormones requires the coordinated expression of the enzymes that comprise the pathways via which specific hormones are synthesized. These pathways and their associated enzymes are typically subject to regulation consisting of trophic hormone stimuli and feedback mechanisms. Very few tissues contribute substantially to de novo steroidogenesis, primarily the adrenal glands, the gonads, and the placenta. Both the embryonic origins and the signaling mechanisms for the adrenals and gonads are similar, and steroid synthesis in these two glands are the major focus of this review. We will further describe peripheral steroid metabolism and the regulation of steroid hormone potency in target tissues. In addition, we will briefly discuss the congenital adrenal hyperplasias to illustrate the principles developed in the initial sections. Finally, we will discuss some recent developments in steroidogensis, focusing on cytochrome P450 oxidoreductase deficiency and the alternate or "backdoor" pathway to dihydrotestosterone. We will conclude with a description of aberrant signaling mechanisms observed in adrenal tumors as a further example of how these pathways can be disturbed in pathologic states.