Characterization of the molecular genetic pathology in patients with 11β-hydroxylase deficiency

Targeted long-read sequencing identifies missing pathogenic variant in unsolved 11β-hydroxylase deficiency

BACKGROUND

11β-hydroxylase deficiency (11β-OHD), caused by homozygosity or compound heterozygosity CYP11B1 variants, is the second most common cause of congenital adrenal hyperplasia (CAH). Due to the high degree of sequence identity between CYP11B1 and CYP11B2, chimeric genes, and complex structural variants (SVs), the conventional approach to gene testing for 11β-OHD is facing challenges. The study aimed to clarify the underlying genetic causes of two siblings of a Chinese family with 11β-OHD.

METHODS

Peripheral blood samples and clinical information were collected from subjects and their family members. Sex steroid concentrations were measured using LC-MS/MS. Long-range PCR-based next-generation sequencing (NGS), PCR assay and target long-read sequencing were used to detect the pathogenic variants.

RESULTS

Early onset hypertension, increased serum levels of adrenocorticotropin (ACTH), progesterone, testosterone, and decreased cortisol and potassium were detected in both affected siblings. Long-range PCR-based NGS identified a heterozygous missense variant (NM_000497.4:c.281 C > T, p.P94> L) in CYP11B1 gene in the two siblings. PCR detected no chimeric CYP11B2/CYP11B1 gene. We finally identified a second pathogenic variant in CYP11B1 gene via target long-read sequencing (T-LRS). This novel variant was a deletion-insertion variant and located chr8:143957269-143,957,579 (hg19) with the insertion of 'ACAG' (NM_000497.4:c.954 + 78_980delinsACAG), which was in trans with CYP11B1: c.281 C > T.

CONCLUSIONS

Our study suggests that the integrated long-range PCR-based NGS and T-LRS seem to be the most reliable and accurate method for 11β-OHD genetic diagnosis and carrier sequencing.

Rare forms of congenital adrenal hyperplasia

Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders due to pathogenic variants in genes encoding enzymes and cofactors involved in adrenal steroidogenesis. Although 21-hydroxylase, 11β-hydroxylase, 3β-hydroxysteroid dehydrogenase type 2, 17α-hydroxylase/17,20-lyase, P450 oxidoreductase, steroidogenic acute regulatory protein, cholesterol side-chain cleavage enzyme deficiencies are considered within the definition of CAH, the term 'CAH' is often used to refer to '21-hydroxylase deficiency (21OHD)' since 21OHD accounts for approximately 95% of CAH in most populations. The prevalence of the rare forms of CAH varies according to ethnicity and geographical location. In most cases, the biochemical fingerprint of impaired steroidogenesis points to the specific subtypes of CAH, and genetic testing is usually required to confirm the diagnosis. Despite there are significant variations in clinical characteristics and management, most data about the rare CAH forms are extrapolated from 21OHD. This review article aims to collate the currently available data about the diagnosis and the management of rare forms of CAH.

Mineralocorticoid receptor antagonist monotherapy in pediatric non-classical 11β-hydroxylase deficiency

OBJECTIVES

Congenital adrenal hyperplasia (CAH) is an uncommon genetic disorder which affects cortisol production in the adrenal glands. It is usually treated with glucocorticoids. We present a case of non-classical CAH caused by the partial deficiency of 11 beta-hydroxylase (11βOH) which was treated with aldosterone antagonist (eplerenone) monotherapy.

CASE PRESENTATION

An adolescent male was diagnosed with 11 beta-hydroxylase deficiency (11βOHD) at 13 years of age when he presented with hypertension, fatigue and headaches. He was initially treated with glucocorticoids, but requested an alternative therapy. Eplerenone was commenced at 25 mg with subsequent dose increases to 100 mg daily. His hypertension was controlled on this regimen, achieving a 24 h average blood pressure of 124/81 mmHg.

CONCLUSIONS

CAH caused by 11βOHD is a known cause of hypertension. It is usually managed with glucocorticoids, and antihypertensives are added if blood pressure remains uncontrolled. In this case, glucocorticoid therapy was not tolerated and treatment with aldosterone antagonist monotherapy was effective in controlling his hypertension.

Molecular analysis of 12 Chinese patients with 11β-hydroxylase deficiency and in vitro functional study of 20 CYP11B1 missense variants

Steroid 11β-hydroxylase deficiency (11β-OHD) is a rare autosomal recessive disorder caused by pathogenic variants of CYP11B1 gene. This study aimed to perform molecular analysis of a Chinese 11β-OHD series and in vitro functional study of twenty CYP11B1 missense variants. Twelve Chinese patients with clinical diagnosis of 11β-OHD were included in the study to analyze their molecular etiology. Genomic DNA of patients was extracted to be sequenced all coding exons and intronic flanking sequences of CYP11B1. Fourteen missense variants found in 12 patients mentioned above along with 6 missense variants previously reported by our team were evaluated functionally. Amino acid substitutions were analyzed with computational program to determine their effects on the three-dimensional structure of CYP11B1 protein. Clinical characteristics and hormone levels at baseline of the 18 patients carrying 18 missense variants aforementioned were recorded to perform genotype-phenotype correlation. A total of 21 rare variants including 9 novel and 12 recurrent ones were identified in 12 patients, out of which 17 were missense, 2 were nonsense, 1 was a splice site variant, and 1 was a deletion-insertion variant. Results of in vitro functional study revealed that 3 out of 20 missense mutants (p.Leu3Pro, p.Gly267Ser, and p.Ala367Ser) had partial enzyme activity and the other 17 had little enzymatic activity. The impairment degree of enzymatic activity in vitro functional study was also reflected in the severity degree of interaction change between the wild-type/mutant-type amino acid and its adjacent amino acids in three-dimensional model. In conclusion, the addition of 9 novel variants expands the spectrum of CYP11B1 pathogenic variants. Our results demonstrate that twenty CYP11B1 variants lead to impaired 11β-hydroxylase activity in vitro. Visualizing these variants in the three-dimensional model structure of CYP11B1 protein can provide a plausible explanation for the results measured in vitro.

Getting pregnant with congenital adrenal hyperplasia: Assisted reproduction and pregnancy complications. A systematic review and meta-analysis

Many patients with congenital adrenal hyperplasia (CAH) refrain from seeking pregnancy, suffer from infertility or worry about pregnancy complications, mainly due to genitalia abnormalities, anovulation, unreceptive endometrium and metabolic disturbances. Despite those challenges, many live births have been reported. In this systematic review, we focused on the key to successful assisted reproduction strategies and the potential pregnancy complications. We did a systematic literature search of Pubmed, Medline and Scopus for articles reporting successful pregnancies in CAH other than 21-hydroxylase deficiency, and found 25 studies reporting 39 pregnancies covering deficiency in steroidogenic acute regulatory protein, 17α-hydroxylase/17,20-lyase, 11β-hydroxylase, P450 oxidoreductase, cytochrome b5 and 3β-hydroxysteroid dehydrogenase. We summarized various clinical manifestations and tailored reproduction strategy for each subtype. Furthermore, a meta-analysis was performed to evaluate the pregnancy complications of CAH patients. A total of 19 cross-sectional or cohort studies involving 1311 pregnancies of classic and non-classic CAH patients were included. Surprisingly, as high as 5.5% (95% CI 2.3%-9.7%) of pregnancies were electively aborted, and the risk was significantly higher in those studies with a larger proportion of classic CAH than those with only non-classical patients (8.43% (4.1%-13.81%) VS 3.75%(1.2%-7.49%)), which called for better family planning. Pooled incidence of miscarriage was 18.2% (13.4%-23.4%) with a relative risk (RR) of 1.86 (1.27-2.72) compared to control. Glucocorticoid treatment in non-classical CAH patients significantly lowered the miscarriage rate when compared to the untreated group (RR 0.25 (0.13-0.47)). CAH patients were also more susceptible to gestational diabetes mellitus, with a prevalence of 7.3% (2.4%-14.1%) and a RR 2.57 (1.29-5.12). However, risks of preeclampsia, preterm birth and small for gestational age were not significantly different. 67.8% (50.8%-86.9%) CAH patients underwent Cesarean delivery, 3.86 (1.66-8.97) times the risk of the control group. These results showed that fertility is possible for CAH patients but special care was necessary when planning, seeking and during pregnancy.

Systematic Review Registration

PROSPERO https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=342642, CRD42022342642.

Increased systemic and adipose 11β-HSD1 activity in idiopathic intracranial hypertension

Context

Idiopathic intracranial hypertension (IIH) is a disease of raised intracranial pressure (ICP) of unknown etiology. Reductions in glucocorticoid metabolism are associated with improvements in IIH disease activity. The basal IIH glucocorticoid metabolism is yet to be assessed.

Objective

The objective of this study was to determine the basal glucocorticoid phenotype in IIH and assess the effects of weight loss on the IIH glucocorticoid phenotype.

Design

A retrospective case-control study and a separate exploratory analysis of a prospective randomized intervention study were carried out.

Methods

The case-control study compared female IIH patients to BMI, age, and sex-matched controls. In the randomized intervention study, different IIH patients were randomized to either a community weight management intervention or bariatric surgery, with patients assessed at baseline and 12 months. Glucocorticoid levels were determined utilizing 24-h urinary steroid profiles alongside the measurement of adipose tissue 11β-HSD1 activity.

Results

Compared to control subjects, patients with active IIH had increased systemic 11β-hydroxysteroid dehydrogenase (11β-HSD1) and 5α-reductase activity. The intervention study demonstrated that weight loss following bariatric surgery reduced systemic 11β-HSD1 and 5α-reductase activity. Reductions in these were associated with reduced ICP. Subcutaneous adipose tissue explants demonstrated elevated 11β-HSD1 activity compared to samples from matched controls.

Conclusion

The study demonstrates that in IIH, there is a phenotype of elevated systemic and adipose 11β-HSD1 activity in excess to that mediated by obesity. Bariatric surgery to induce weight loss was associated with reductions in 11β-HSD1 activity and decreased ICP. These data reflect new insights into the IIH phenotype and further point toward metabolic dysregulation as a feature of IIH.

Challenges in the treatment of late-identified untreated congenital adrenal hyperplasia due to CYP11B1 deficiency: Lessons from a developing country

BACKGROUND

Congenital Adrenal Hyperplasia (CAH) due to CYP11B1 is a rare autosomal recessive adrenal disorder that causes a decrease in cortisol production and accumulation of adrenal androgens and steroid precursors with mineralocorticoid activity. Clinical manifestations include cortisol deficiency, ambiguous genitalia in females (differences of sex development (DSD)), and hypertension. Medical treatment recommendations are well defined, consisting of glucocorticoid treatment to substitute glucocorticoid deficiency and consequently normalize adrenal androgen and precursors levels. Current guidelines also emphasize the need for specialized multidisciplinary DSD teams and psychosocial support. In many developing countries, care for DSD patients, especially when caused by an adrenal disease, is challenging due to the lack of infrastructure, knowledge, and medication.

OBJECTIVE

The study aims to report the conflicting decision-making process of medical treatment and sex assignment in late-identified CAH patients in developing countries.

METHODS

We describe the clinical and biochemical findings and the psychological assessment of five affected but untreated family members with CAH due to CYP11B1 deficiency.

RESULTS

All patients had a 46,XX karyotype, ambiguous genitalia, low cortisol levels, and hypertension. Two identified as males, two as females, and one had undecided gender. The patients were counselled that refusing treatment will lead to infertility and the potential risk of developing Addisonian crisis and severe hypertension. However, all 46,XX CAH males refused treatment with glucocorticoids due to the expected lowering of adrenal androgens as their main source of testosterone. None of the patients developed Addisonian crisis, probably due to some residual cortisol activity and glucocorticoid activity of elevated adrenal steroid precursors.

CONCLUSION

Medical treatment and sex assignment in late-identified 46,XX CAH patients in Indonesia may often depend on local and cultural factors. The management of DSD conditions may have to be individualized and integrated into the psychological and social context of the affected family.

Challenges in treatment of patients with non-classic congenital adrenal hyperplasia

Congenital adrenal hyperplasia (CAH) due to 21α-hydroxylase deficiency (21OHD) or 11β-hydroxylase deficiency (11OHD) are congenital conditions with affected adrenal steroidogenesis. Patients with classic 21OHD and 11OHD have a (nearly) complete enzyme deficiency resulting in impaired cortisol synthesis. Elevated precursor steroids are shunted into the unaffected adrenal androgen synthesis pathway leading to elevated adrenal androgen concentrations in these patients. Classic patients are treated with glucocorticoid substitution to compensate for the low cortisol levels and to decrease elevated adrenal androgens levels via negative feedback on the pituitary gland. On the contrary, non-classic CAH (NCCAH) patients have more residual enzymatic activity and do generally not suffer from clinically relevant glucocorticoid deficiency. However, these patients may develop symptoms due to elevated adrenal androgen levels, which are most often less elevated compared to classic patients. Although glucocorticoid treatment can lower adrenal androgen production, the supraphysiological dosages also may have a negative impact on the cardiovascular system and bone health. Therefore, the benefit of glucocorticoid treatment is questionable. An individualized treatment plan is desirable as patients can present with various symptoms or may be asymptomatic. In this review, we discuss the advantages and disadvantages of different treatment options used in patients with NCCAH due to 21OHD and 11OHD.

Adrenal hyperplasias in childhood: An update

Pediatric adrenocortical hyperplasias are rare; they usually present with Cushing syndrome (CS); of them, isolated micronodular adrenal disease and its variant, primary pigmented adrenocortical disease are the most commonly encountered. Most cases are due to defects in the cyclic AMP/protein kinase A (cAMP/PKA) pathway, although a few cases remain without an identified genetic defect. Another cause of adrenal hyperplasia in childhood is congenital adrenal hyperplasia, a group of autosomal recessive disorders that affect steroidogenic enzymes in the adrenal cortex. Clinical presentation varies and depends on the extent of the underlying enzymatic defect. The most common form is due to 21-hydroxylase deficiency; it accounts for more than 90% of the cases. In this article, we discuss the genetic etiology of adrenal hyperplasias in childhood.

Disorders of Sex Development of Adrenal Origin

Disorders of Sex Development (DSD) are anomalies occurring in the process of fetal sexual differentiation that result in a discordance between the chromosomal sex and the sex of the gonads and/or the internal and/or external genitalia. Congenital disorders affecting adrenal function may be associated with DSD in both 46,XX and 46,XY individuals, but the pathogenic mechanisms differ. While in 46,XX cases, the adrenal steroidogenic disorder is responsible for the genital anomalies, in 46,XY patients DSD results from the associated testicular dysfunction. Primary adrenal insufficiency, characterized by a reduction in cortisol secretion and overproduction of ACTH, is the rule. In addition, patients may exhibit aldosterone deficiency leading to salt-wasting crises that may be life-threatening. The trophic effect of ACTH provokes congenital adrenal hyperplasia (CAH). Adrenal steroidogenic defects leading to 46,XX DSD are 21-hydroxylase deficiency, by far the most prevalent, and 11β-hydroxylase deficiency. Lipoid Congenital Adrenal Hyperplasia due to StAR defects, and cytochrome P450scc and P450c17 deficiencies cause DSD in 46,XY newborns. Mutations in SF1 may also result in combined adrenal and testicular failure leading to DSD in 46,XY individuals. Finally, impaired activities of 3βHSD2 or POR may lead to DSD in both 46,XX and 46,XY individuals. The pathophysiology, clinical presentation and management of the above-mentioned disorders are critically reviewed, with a special focus on the latest biomarkers and therapeutic development.

Clinical and Hormonal Profiles Correlate With Molecular Characteristics in Patients With 11β-Hydroxylase Deficiency

BACKGROUND

Given the rarity of 11β-hydroxylase deficiency (11βOHD), there is a paucity of data about the differences in clinical and biochemical characteristics of classic (C-11βOHD) and nonclassic 11βOHD (NC-11βOHD).

OBJECTIVE

To characterize a multicenter pediatric cohort with 11βOHD.

METHOD

The clinical and biochemical characteristics were retrospectively retrieved. CYP11B1 gene sequencing was performed. Seventeen plasma steroids were quantified by liquid chromatography-mass spectrometry and compared to that of controls.

RESULTS

102 patients (C-11βOHD, n = 92; NC-11βOHD, n = 10) from 76 families (46,XX; n = 53) had biallelic CYP11B1 mutations (novel 9 out of 30). Five 46,XX patients (10%) were raised as males. Nineteen patients (19%) had initially been misdiagnosed with 21-hydroxylase deficiency. Female adult height was 152 cm [-1.85 SD score (SDS)] and male 160.4 cm (-2.56 SDS).None of the NC-11βOHD girls had ambiguous genitalia (C-11βOHD 100%), and none of the NC-11βOHD patients were hypertensive (C-11βOHD 50%). Compared to NC-11βOHD, C-11βOHD patients were diagnosed earlier (1.33 vs 6.9 years; P < 0.0001), had higher bone age-to-chronological age (P = 0.04) and lower adult height (-2.46 vs -1.32 SDS; P = 0.05). The concentrations of 11-oxygenated androgens and 21-deoxycortisol were low in all patients. The baseline ACTH and stimulated cortisol were normal in NC-11βOHD. Baseline cortisol; cortisone; 11-deoxycortisol; 11-deoxycorticosterone and corticosterone concentrations; and 11-deoxycortisol/cortisol, 11-deoxycorticosterone/cortisol, and androstenedione/cortisol ratios were higher in C-11βOHD than NC-11βOHD patients (P < 0.05). The 11-deoxycortisol/cortisol ratio >2.2, <1.5, and <0.1 had 100% specificity to segregate C-11βOHD, NC-11βOHD, and control groups.

CONCLUSION

NC-11βOHD can escape from clinical attention due to relatively mild clinical presentation. However, steroid profiles enable the diagnosis, differential diagnosis, and subtyping of 11βOHD.

Expanding genetic spectrum and discriminatory role of steroid profiling by LC-MS/MS in 11β-hydroxylase deficiency

OBJECTIVE

To report clinical, hormonal and structural effects of CYP11B1 pathogenic variations in Indian patients with 11β-hydroxylase deficiency (11βOHD) and find hormonal criteria that accurately distinguish 11βOHD from 21α-hydroxylase deficiency (21OHD).

DESIGN

Retrospective record review of genetically diagnosed patients with 11βOHD.

PATIENTS AND MEASUREMENTS

Clinical features, hormonal parameters at diagnosis (by immunoassay) and recent follow-up of 13 genetically proven 11βOHD patients managed at our centre were retrospectively reviewed. ACTH-stimulated serum adrenal steroids (measured by LC-MS/MS) of 11βOHD were compared with those of simple virilizing and non-classic 21OHD. Structural analysis of the observed pathogenic variations was performed by computational modelling.

RESULTS

Nine (four females) and four (all females) patients had classic and non-classic disease, respectively. All 11βOHD patients had elevated ACTH-stimulated serum 11-deoxycortisol (26.5-342.7 nmol/L) whereas none had elevated serum 17-hydroxyprogesterone (4.2-21.2 nmol/L); both hormonal parameters distinguished 11βOHD from 21OHD with 100% accuracy. ACTH-stimulated serum cortisol, but not 11-deoxycortisol, clearly distinguished classic (<70 nmol/L) from non-classic (>160 nmol/L) disease. Thirteen (eight novel, two recurrent) pathogenic variants were observed. Only missense mutations were observed among patients with non-classic disease. Computational modelling predicted the possible affection of enzyme structure and function for all the observed missense mutations.

CONCLUSIONS

This first Indian study describes 13 11βOHD patients, including four with the rarer non-classic variant. A total of eight novel pathogenic variants were identified in our study, highlighting regional genetic heterogeneity. Measurement of ACTH-stimulated adrenal steroids by LC-MS/MS will help avoid the misdiagnosis of 11βOHD as 21OHD and has potential to distinguish classic from non-classic 11βOHD.

11β-Hydroxysteroid dehydrogenase type 1 inhibition in idiopathic intracranial hypertension: a double-blind randomized controlled trial

Treatment options for idiopathic intracranial hypertension are limited. The enzyme 11β-hydroxysteroid dehydrogenase type 1 has been implicated in regulating cerebrospinal fluid secretion, and its activity is associated with alterations in intracranial pressure in idiopathic intracranial hypertension. We assessed therapeutic efficacy, safety and tolerability and investigated indicators of in vivo efficacy of the 11β-hydroxysteroid dehydrogenase type 1 inhibitor AZD4017 compared with placebo in idiopathic intracranial hypertension. A multicenter, UK, 16-week phase II randomized, double-blind, placebo-controlled trial of 12-week treatment with AZD4017 or placebo was conducted. Women aged 18–55 years with active idiopathic intracranial hypertension (>25 cmH₂O lumbar puncture opening pressure and active papilledema) were included. Participants received 400 mg of oral AZD4017 twice daily compared with matching placebo over 12 weeks. The outcome measures were initial efficacy, safety and tolerability. The primary clinical outcome was lumbar puncture opening pressure at 12 weeks analysed by intention-to-treat. Secondary clinical outcomes were symptoms, visual function, papilledema, headache and anthropometric measures. In vivo efficacy was evaluated in the central nervous system and systemically. A total of 31 subjects [mean age 31.2 (SD = 6.9) years and body mass index 39.2 (SD = 12.6) kg/m²] were randomized to AZD4017 (n = 17) or placebo (n = 14). At 12 weeks, lumbar puncture pressure was lower in the AZD4017 group (29.7 cmH₂O) compared with placebo (31.3 cmH₂O), but the difference between groups was not statistically significant (mean difference: −2.8, 95% confidence interval: −7.1 to 1.5; P = 0.2). An exploratory analysis assessing mean change in lumbar puncture pressure within each group found a significant decrease in the AZD4017 group [mean change: −4.3 cmH₂O (SD = 5.7); P = 0.009] but not in the placebo group [mean change: −0.3 cmH₂O (SD = 5.9); P = 0.8]. AZD4017 was safe, with no withdrawals related to adverse effects. Nine transient drug-related adverse events were reported. One serious adverse event occurred in the placebo group (deterioration requiring shunt surgery). In vivo biomarkers of 11β-hydroxysteroid dehydrogenase type 1 activity (urinary glucocorticoid metabolites, hepatic prednisolone generation, serum and cerebrospinal fluid cortisol:cortisone ratios) demonstrated significant enzyme inhibition with the reduction in serum cortisol:cortisone ratio correlating significantly with reduction in lumbar puncture pressure (P = 0.005, R = 0.70). This is the first phase II randomized controlled trial in idiopathic intracranial hypertension evaluating a novel therapeutic target. AZD4017 was safe and well tolerated and inhibited 11β-hydroxysteroid dehydrogenase type 1 activity in vivo. Reduction in serum cortisol:cortisone correlated with decreased intracranial pressure. Possible clinical benefits were noted in this small cohort. A longer, larger study would now be of interest.

Clinical and Molecular Analysis of Four Patients With 11β-Hydroxylase Deficiency

Objective: 11β-hydroxylase deficiency (11βOHD) is a rare autosomal recessive disorder caused by mutations in the CYP11B1 gene. It is characterized by virilization, hypertension, and significant final height impairment. In this study, we aim to investigate the clinical and molecular characteristics of four unrelated Chinese patients with 11βOHD disorder. Methods: The clinical information of four 11βOHD patients were carefully reviewed. Genetic analysis was performed using next-generation sequencing (NGS) based panel analysis. NGS coverage depth was analyzed to detect exonic copy-number variants (CNVs) on patient 1. Quantitative PCR (qPCR) was subsequently performed to confirm the CNVs detected from the NGS coverage depth analysis. Results: The mean age of the patients at diagnosis was 4.7 years (range, 2.0-9.3 years). Two genetically female patients (patients 1 and 2) with 11βOHD presented severe virilization of external genitalia and were raised as males. Two genetically male patients (patients 3 and 4) presented precocious puberty. Additionally, patients 1, 3, and 4 presented with hypertension. In patient 4, unilateral adrenal mass was detected and removed at the age of 9 years. Interestingly, the height of patient 4 (174.4 cm, +6.7 SD) wasn't impaired and reached his mid-parental height (173 cm). Three novel variants in the CYP11B1 gene (c.1150_1153del, c.217C>T, and c.400G>C) were identified by NGS. Various bioinformatics tools revealed potential pathogenic effects for the novel variants, and evolutionary-conservation revealed that the novel missense variant affected an amino acid that is highly conserved among species. Furthermore, NGS coverage depth analysis and qPCR identified a novel heterozygous deletion of exons 1-6 in patient 1. Conclusion: Our study expands the spectrum of mutations of the CYP11B1 gene in Chinese population. In addition, We reported the first case of a patient with classical 11βOHD disorder, whose final height wasn't compromised.

Long-term follow-up of a female patient with non-classical 11β-hydroxylase deficiency and two novel mutations in CYP11B1

11β-Hydroxylase deficiency is the second most common enzyme disorder after 21-hydroxylase deficiency causing congenital adrenal hyperplasia (CAH_11β). In females, the clinical phenotype of CAH_11β classic forms is associated with ambiguous genitalia, virilization and hypertension, while most common complaints in milder non-classic forms include hirsutism, acne, menstrual disturbances, and infertility. Herein, we present clinical and genetic characteristics of an adult woman with 11β-hydroxylase deficiency, hypertension and infertility; she has been followed up from her first pregnancy to her early menopause. Genetic analyses of the patient revealed a compound-heterozygosity due to two variants in the CYP11B1 gene p.Val316Met and p.Asp480ThrfsTer2. Both mutations have not been previously reported as pathogenic in the literature. Emerging questions concerning the clinical management, fertility potential, mineral corticoid abnormalities and perimenopausal transition in patients with non-classic CAH_11β have also been briefly discussed. The presented case of an adult woman with CAH_11β shows that the proper diagnosis and close monitoring of patients with different CAH forms might ensure good therapy adherence and successful fertility.

Non-classical 11β-hydroxylase deficiency caused by compound heterozygous mutations: a case study and literature review

BACKGROUND

11β-hydroxylase deficiency (11OHD) is extremely rare, and reports of non-classical 11OHD are even rarer. Non-classical 11OHD usually presents as premature adrenarche, hyperandrogenism, menstrual disorders, and hypertension. Because the symptoms of non-classical 11OHD are mild, delayed diagnosis or misdiagnosis as polycystic ovary syndrome or primary hypertension is common.

CASE PRESENTATION

This paper introduces a case of a young female patient presenting hypertension and menstrual disorders. Laboratory examination revealed increased androgen levels, mild adrenal hyperplasia, mild left ventricular hypertrophy, and mild sclerosis of the lower limb arteries. 11OHD was confirmed by genetic testing, and the patient was found to carry compound heterozygous mutations in CYP11B1 (c.583 T > C and c.1358G > A). The mutation Y195H is located in exon 3 and has not been reported previously. In silico studies indicated that this mutation may cause reduced enzymatic activity. After treatment with hydrocortisone and spironolactone, blood pressure was brought under good control, and menstruation returned to normal. We also conducted a retrospective review of previously reported cases in the literature (over 170 cases since 1991).

CONCLUSIONS

Early diagnosis of non-classical 11OHD is difficult because its symptoms are mild. The possibility of this disease should be considered in patients with early-onset hypertension, menstrual disorders, and hyperandrogenism to provide early treatment and prevent organ damage due to hypertension and hyperandrogenism. CYP11B1 mutations are known to be race-specific and are concentrated in exons 3 and 8, of which mutations in the former are mostly associated with non-classical 11OHD, whereas mutations in the latter are mostly found in classical 11OHD, characterized by severe loss of enzymatic activity.

MECHANISMS IN ENDOCRINOLOGY: Rare defects in adrenal steroidogenesis

Congenital adrenal hyperplasia (CAH) is a group of genetic disorders of adrenal steroidogenesis that impair cortisol synthesis, with compensatory increases in ACTH leading to hyperplastic adrenals. The term 'CAH' is generally used to mean 'steroid 21-hydroxylase deficiency' (21OHD) as 21OHD accounts for about 95% of CAH in most populations; the incidences of the rare forms of CAH vary with ethnicity and geography. These forms of CAH are easily understood on the basis of the biochemistry of steroidogenesis. Defects in the steroidogenic acute regulatory protein, StAR, disrupt all steroidogenesis and are the second-most common form of CAH in Japan and Korea; very rare defects in the cholesterol side-chain cleavage enzyme, P450scc, are clinically indistinguishable from StAR defects. Defects in 3β-hydroxysteroid dehydrogenase, which also causes disordered sexual development, were once thought to be fairly common, but genetic analyses show that steroid measurements are generally unreliable for this disorder. Defects in 17-hydroxylase/17,20-lyase ablate synthesis of sex steroids and also cause mineralocorticoid hypertension; these are common in Brazil and in China. Isolated 17,20-lyase deficiency can be caused by rare mutations in at least three different proteins. P450 oxidoreductase (POR) is a co-factor used by 21-hydroxylase, 17-hydroxylase/17,20-lyase and aromatase; various POR defects, found in different populations, affect these enzymes differently. 11-Hydroxylase deficiency is the second-most common form of CAH in European populations but the retention of aldosterone synthesis distinguishes it from 21OHD. Aldosterone synthase deficiency is a rare salt-losing disorder. Mild, 'non-classic' defects in all of these factors have been described. Both the severe and non-classic disorders can be treated if recognized.

Congenital Adrenal Hyperplasia

The congenital adrenal hyperplasias comprise a family of autosomal recessive disorders that disrupt adrenal steroidogenesis. The most common form is due to 21-hydroxylase deficiency associated with mutations in the 21-hydroxylase gene, which is located at chromosome 6p21. The clinical features associated with each disorder of adrenal steroidogenesis represent a clinical spectrum that reflect the consequences of the specific mutations. Treatment goals include normal linear growth velocity and "on-time" puberty in affected children. For adolescent and adult women, treatment goals include regularization of menses, prevention of progression of hirsutism, and preservation of fertility. For adolescent and adult men, prevention and early treatment of testicular adrenal rest tumors is beneficial. In this article key aspects regarding pathophysiology, diagnosis, and treatment of congenital adrenal hyperplasia are reviewed.

Genetics of Congenital Adrenal Hyperplasia

Congenital adrenal hyperplasia (CAH) refers to a group of autosomal recessive disorders due to single-gene defects in the various enzymes required for cortisol biosynthesis. CAH represents a continuous phenotypic spectrum with more than 95% of all cases caused by 21-hydroxylase deficiency. Genotyping is an important tool in confirming the diagnosis or carrier state, provides prognostic information on disease severity, and is essential for genetic counseling. In this article, the authors provide an in-depth discussion on the genetics of CAH, including genetic diagnosis, molecular analysis, genotype-phenotype relationships, and counseling of patients and their families.

Novel and prevalent CYP11B1 gene mutations in Turkish patients with 11-β hydroxylase deficiency

11β-Hydroxylase deficiency is the second most frequent type of congenital adrenal hyperplasia and is more common in those of Turkish descent than in other populations. The purpose of this study is to examine the spectrum of CYP11B1 gene mutations in Turkish patients with 11β-hydroxylase deficiency. Twenty-eight patients from 24 families, ages ranging from 0.1 to 7 years, were included in the study. Clinical diagnosis was based on virilization and high levels of 11-deoxycortisol. Twenty-six cases exhibited the classical and 2 cases the non-classical form. Mutation screening of 9 CYP11B1 exons was performed by direct DNA sequence analysis, specifically amplifying CYP11B1 gene fragments while avoiding simultaneous amplification of homologous CYP11B2 gene sequences. Seventeen different mutations were detected, 6 of which are novel (p.Gln189Hisfs*70, p.Glu198Gly, p.Thr318Lys, p.Gly446Ser, IVS8+5G>C and exon 3-5 del). All of the identified mutations resulted in the classical form with severe virilization, except for the p.Gly446Ser mutation, which caused a late-onset type of 11β-hydroxylase deficiency. The c.954G>A;p.Thr318Thr mutation was the most common in our cohort, with an allele frequency of 14.6%.Of the CYP11B1 gene mutations detected, 75% were found in exons 3, 5 and 7 and the half of the mutations were nonsense, splice site, deletion or insertion mutations, causing severe virilization in female patients. The findings are important for genetic counseling and the prenatal diagnosis of Turkish patients with 11β-hydroxylase deficiency.

Genetics of 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 deficiency of one of four steroidogenic enzymes involved in cortisol biosynthesis or in the electron donor enzyme P450 oxidoreductase (POR) that serves as electron donor to steroidogenic cytochrome P450 (CYP) type II enzymes. The biochemical and clinical phenotype depends on the specific enzymatic defect and the impairment of specific enzyme activity. Defects of steroid 21-hydroxylase (CYP21A2) and 11beta-hydroxylase (CYP11B1) only affect adrenal steroidogenesis, whereas 17alpha-hydroxylase (CYP17A1) and 3beta-hydroxysteroid dehydrogenase type 2 (HSD3B2) deficiency also impact on gonadal steroid biosynthesis. Inactivating POR gene mutations are the cause of CAH manifesting with apparent combined CYP17A1-CYP21A2 deficiency. P450 oxidoreductase deficiency (ORD) has a complex phenotype including two unique features not observed in any other CAH variant: skeletal malformations and severe genital ambiguity in both sexes.