Inhibition of CYP21A2 enzyme activity caused by novel missense mutations identified in Brazilian and Scandinavian patients

Congenital Adrenal Hyperplasia with Combined 21-hydroxylase deficiency and 17α-hydroxylase/17,20-lyase deficiency: An undervirilized male

21-hydroxylase deficiency stands as the most prevalent form of congenital adrenal hyperplasia, primarily resulting from mutations in the CYP21A2 gene. On the other hand, mutations within the CYP17A1 gene lead to 17α-hydroxylase/17,20-lyase enzyme deficiencies. The scarcity of 17-OH deficiency is noteworthy, accounting for less than 1% of all congenital adrenal hyperplasia cases. The male patient, born from a first-degree cousin marriage, exhibited several symptoms, including left undescended testis, micropenis, penile chord, left sensorineural hearing loss, and gynecomastia. He reported micropenis as a concern at the age of 13.5 years. His hormone profile revealed high levels of serum 17-hydroxyprogesterone, progesterone, and pregnenolone. In this case with a 46 XY karyotype, suspicions arose regarding Cytochrome P450 oxidoreductase deficiency due to ambiguous genitalia and an atypical hormone profile. Analysis unveiled two distinct homozygous and pathogenic variants in the CYP21A2 and CYP17A1 genes. Notably, mineralocorticoid precursors escalated, while cortisol and sex steroid precursors decreased during the high (250 mcg) dose ACTH stimulation test. The mutation c.1169C > G (p.Thr390Arg) in CYP17A1, which is the second documented case in literature, stands out due to its unique set of accompanying features. Mutations occurring in CYP21A2 and CYP17A1 result in complete or partial enzyme deficiencies, and the detection of homozygous mutations in two different enzyme systems within the steroidogenic pathway is noteworthy.

Normal ambulatory blood pressure in young adults with 21-hydroxylase enzyme deficiency undergoing glucocorticoid replacement therapy

Objective

Herein, we compared ambulatory blood pressure (ABP) between young adults with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase enzyme (21OHase) deficiency and a control group. Additionally, we analyzed correlations between the glucocorticoid dose and androgen levels and ABP parameters.

Subjects and methods

This case-control study included 18 patients (6 males and 12 females) and 19 controls (8 males and 11 females) matched by age (18-31 years). ABP monitoring was used to estimate blood pressure (BP) over a 24-h period.

Results

No difference was noted between patients and controls in terms of systolic BP (males, 115.5 ± 5.6 vs. 117.0 ± 9.3, P = 0.733; and females, 106.4 ± 7.9 vs. 108.4 ± 7.6, P = 0.556, respectively) and diastolic BP during 24 h (males, 62.8 ± 7.5 vs. 66.2 ± 5.6, P = 0.349; and females, 62.7 ± 4.9 vs. 62.3 ± 4.9, P = 0.818, respectively). Systolic and diastolic BP and pulse pressure during daytime and nocturnal periods were similar between patients and controls. Furthermore, no differences were detected in the percentage of load and impaired nocturnal dipping of systolic and diastolic BP between patients and controls during the 24-h period. Additionally, the glucocorticoid dose (varying between r = -0.24 to 0.13, P > 0.05) and androgens levels (varying between r = 0.01 to 0.14, P > 0.05) were not associated with ABP parameters.

Conclusion

No signs of an elevated risk for hypertension were observed based on ABP monitoring in young adults with CAH attributed to 21OHase deficiency undergoing glucocorticoid replacement therapy.

Genetic and clinical characteristics including occurrence of testicular adrenal rest tumors in Slovak and Slovenian patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency

OBJECTIVE

To analyze the mutational spectrum, clinical characteristics, genotype-phenotype correlations, testicular adrenal rests tumor prevalence, and role of neonatal screening in congenital adrenal hyperplasia (CAH) patients from Slovakia and Slovenia.

DESIGN AND METHODS

Data were obtained from 104 patients with CAH registered in Slovak and Slovenian databases. Low-resolution genotyping was performed to detect the most common point mutations. To detect deletions, conversions, point mutations, or other sequence changes in the CYP21A2 gene, high-resolution genotyping was performed. Genotypes were classified according to residual 21-hydroxylase activity (null, A, B, C).

RESULTS

64% of the individuals had the salt-wasting form (SW-CAH), 15% the simple virilizing form (SV-CAH), and 21% the non-classic (NC-CAH). CYP21A2 gene deletion/conversion and c.293-13A/C>G pathogenic variant accounted together for 55.5% of the affected alleles. In SV-CAH p.Ile172Asn was the most common pathogenic variant (28.13%), while in NC-CAH p.Val282Leu (33.33%), CYP21A2 gene deletion/conversion (21.43%), c.293-13A/C>G (14.29%), Pro30Leu (11.90%). The frequency of alleles with multiple pathogenic variants was higher in Slovenian patients (15.83% of all alleles). Severe genotypes (0 and A) correlated well with the expected phenotype (SW in 94.74% and 97.3%), while less severe genotypes (B and C) correlated weaklier (SV in 50% and NC in 70.8%). The median age of SW-CAH patients at the time of diagnosis was 6 days in Slovakia vs. 28.5 days in Slovenia (p=0.01). Most of the Slovak patients in the cohort were detected by NBS. (24 out of 29). TARTs were identified in 7 out of 24 male patients, of whom all (100%) had SW-CAH and all had poor hormonal control. The median age at the diagnosis of TARTs was 13 years.

CONCLUSION

The study confirmed the importance of neonatal screening, especially in the speed of diagnosis of severe forms of CAH. The prediction of the 21-OH deficiency phenotype was reasonably good in the case of severe pathogenic variants, but less reliable in the case of milder pathogenic variants, which is consistent compared to data from other populations. Screening for TARTs should be realized in all male patients with CAH, since there is possible remission when identified early.

Genotype-phenotype correlation in patients with 21-hydroxylase deficiency

INTRODUCTION

21-hydroxylase deficiency (21OHD) is the most common cause of congenital adrenal hyperplasia (CAH). However, patients with 21OHD manifest various phenotypes due to a wide-spectrum residual enzyme activity of different CYP21A2 mutations.

METHODS

A total of 15 individuals from three unrelated families were included in this study. Target Capture-Based Deep Sequencing and Restriction Fragment Length Polymorphism was conducted on peripheral blood DNA of the three probands to identify potential mutations/deletions in CYP21A2; Sanger sequencing was conducted with the DNA from the family members of the probands.

RESULTS

Dramatically different phenotypes were seen in the three probands of CAH with different compound heterozygous mutations in CYP21A2. Proband 1 manifested simple virilizing with mutations of 30-kb deletion/c.[188A>T;518T>A], the latter is a novel double mutants classified as SV associated mutation. Although both probands carry the same compound mutations [293-13C>G]:[518T>A], gonadal dysfunction and giant bilateral adrenal myelolipoma were diagnosed for proband 2 and proband 3, respectively.

CONCLUSION

Both gender and mutations contribute to the phenotypes, and patients with the same compound mutations and gender could present with different phenotypes. Genetic analysis could help the etiologic diagnosis, especially for atypical 21OHD patients.

Higher Body Fat but Similar Phase Angle Values in Patients with the Classical Form of Congenital Adrenal Hyperplasia in Comparison to a Control Group

This study aimed to compare phase angle (PhA) and bioelectrical impedance vector analysis (BIVA) values between adult patients with congenital adrenal hyperplasia caused by 21-hydroxylase deficiency (CAH21OHD) and a control group. A total of 22 patients (15 women, 22.9 ± 3.7 years) were compared with 17 controls (11 women, 27.0 ± 2.5 years). Body composition was determined by dual-energy X-ray absorptiometry. Bioelectrical impedance was used to calculate PhA, and BIVA was performed using specific software. Student’s t-test and analysis of covariance were used to compare groups. Hedges’ G and partial n2 were calculated for the effect estimates. Hotelling’s t2 test was used to compare the mean impedance vectors between the groups. The Mahalanobis test was used to determine the distance between confidence ellipses. Patients with CAH21OHD had a higher fat mass percentage than that of the control group (both sexes). There was no significant difference in PhA values between groups (CAH21OHD vs. control) in females (6.9° vs. 6.3°, p = 0.092) and males (8.2° vs. 8.1°, p = 0.849), after adjusting for covariates (age and height). BIVA analysis showed a significant difference in the mean impedance vectors between the female groups (T2 = 15.9, D = 1.58, p = 0.003) owing to the higher reactance/height (Δ = 8.5; p < 0.001) of the patients. The PhA did not significantly differ between the groups. Female patients had significantly higher reactance values. However, further studies are needed to determine the usefulness of bioimpedance parameters in evaluating the hydration status and cellular integrity of patients with CAH21OHD.

Joint Analysis of Phenotypic and Genomic Diversity Sheds Light on the Evolution of Xenobiotic Metabolism in Humans

Variation in genes involved in the absorption, distribution, metabolism, and excretion of drugs (ADME) can influence individual response to a therapeutic treatment. The study of ADME genetic diversity in human populations has led to evolutionary hypotheses of adaptation to distinct chemical environments. Population differentiation in measured drug metabolism phenotypes is, however, scarcely documented, often indirectly estimated via genotype-predicted phenotypes. We administered seven probe compounds devised to target six cytochrome P450 enzymes and the P-glycoprotein (P-gp) activity to assess phenotypic variation in four populations along a latitudinal transect spanning over Africa, the Middle East, and Europe (349 healthy Ethiopian, Omani, Greek, and Czech volunteers). We demonstrate significant population differentiation for all phenotypes except the one measuring CYP2D6 activity. Genome-wide association studies (GWAS) evidenced that the variability of phenotypes measuring CYP2B6, CYP2C9, CYP2C19, and CYP2D6 activity was associated with genetic variants linked to the corresponding encoding genes, and additional genes for the latter three. Instead, GWAS did not indicate any association between genetic diversity and the phenotypes measuring CYP1A2, CYP3A4, and P-gp activity. Genome scans of selection highlighted multiple candidate regions, a few of which included ADME genes, but none overlapped with the GWAS candidates. Our results suggest that different mechanisms have been shaping the evolution of these phenotypes, including phenotypic plasticity, and possibly some form of balancing selection. We discuss how these contrasting results highlight the diverse evolutionary trajectories of ADME genes and proteins, consistent with the wide spectrum of both endogenous and exogenous molecules that are their substrates.

Normal bone health in young adults with 21-hydroxylase enzyme deficiency undergoing glucocorticoid replacement therapy

It is of great importance to investigate any potential detrimental effect on bone health in young adults with 21-hydroxylase enzyme deficiency undergoing glucocorticoid replacement therapy. This study demonstrated normal bone health in well-controlled patients. Additionally, glucocorticoid dose may play an important role in the mineral density of femoral neck region.

PURPOSE

To compare regional bone mineral densities (BMDs) and bone statuses of young adults with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase enzyme (21OHase) deficiency with a control group. The duration and dose of glucocorticoid therapy and relative skeletal muscle index (an indicator of sarcopenia) were also analyzed as parameters to predict bone health.

METHODS

This case-control study included 23 patients (7 male and 16 female) and 20 controls (8 male and 12 female) matched by age range (18 to 31 years). Dual energy X-ray absorptiometry and phalangeal quantitative ultrasound (QUS) were used to estimate BMD and bone status, respectively.

RESULTS

No difference was observed between patients and controls (of both sexes) in absolute values of BMD and Z-scores for the total body, lumbar spine, and femoral neck; or the bone status (estimated by phalangeal QUS). Multiple linear regression analysis demonstrated that relative skeletal muscle index independently correlated with BMD of the entire body (β: 0.67, P = 0.007), the lumbar spine (β: 0.73, P = 0.005), and the femoral neck (β: 0.67, P = 0.007). However, the dose of glucocorticoids (β: - 0.38, P = 0.028) independently correlated with BMD in the femoral neck region alone.

CONCLUSION

No signs of change in bone health were observed in patients with CAH when compared to the reference group. Additionally, a marker of sarcopenia was demonstrated to have a role in mineral density mechanisms in all analyzed bone sites. Only the femoral neck BMD seemed to be significantly dependent on glucocorticoid dose.

Characterization of Mutations Causing CYP21A2 Deficiency in Brazilian and Portuguese Populations

Deficiency of 21-hydroxylase enzyme (CYP21A2) represents 90% of cases in congenital adrenal hyperplasia (CAH), an autosomal recessive disease caused by defects in cortisol biosynthesis. Computational prediction and functional studies are often the only way to classify variants to understand the links to disease-causing effects. Here we investigated the pathogenicity of uncharacterized variants in the CYP21A2 gene reported in Brazilian and Portuguese populations. Physicochemical alterations, residue conservation, and effect on protein structure were accessed by computational analysis. The enzymatic performance was obtained by functional assay with the wild-type and mutant CYP21A2 proteins expressed in HEK293 cells. Computational analysis showed that p.W202R, p.E352V, and p.R484L have severely impaired the protein structure, while p.P35L, p.L199P, and p.P433L have moderate effects. The p.W202R, p.E352V, p.P433L, and p.R484L variants showed residual 21OH activity consistent with the simple virilizing phenotype. The p.P35L and p.L199P variants showed partial 21OH efficiency associated with the non-classical phenotype. Additionally, p.W202R, p.E352V, and p.R484L also modified the protein expression level. We have determined how the selected CYP21A2 gene mutations affect the 21OH activity through structural and activity alteration contributing to the future diagnosis and management of CYP21A2 deficiency.

Therapeutic needs from early childhood in four patients with 21-hydroxylase deficiency harboring the P30L mutation on one allele

21-hydroxylase deficiency (21-OHD) is the most common type of congenital adrenal hyperplasia. Phenotypically, 21-OHD can be divided into classical and non-classical (NC) forms. The genotype-phenotype correlation in 21-OHD is well established. The P30L mutation is usually associated with the NC form and common among Japanese patients with the NC form of 21-OHD. Herein, we report the clinical course of four patients with 21-OHD with the P30L mutation on one allele and loss-of-function variants on the other allele. Contrary to the findings of most previous studies, all patients were treated with hydrocortisone, and two required fludrocortisone therapy in early childhood. The management strategies for patients with 21-OHD, especially those with the P30L mutation on at least one allele, should be determined based on the clinical phenotype predicted by the CYP21A2 genotype and individual clinical symptoms and biochemical data.

Cardiovascular dysfunction risk in young adults with congenital adrenal hyperplasia caused by 21-hydroxylase enzyme deficiency

BACKGROUND

The association of congenital adrenal hyperplasia (CAH) caused by 21-hydroxylase enzyme (21OHase) deficiency, duration of treatment and dosage with cardiovascular dysfunction in young adults remains unclear. We aimed to evaluate myocardial function, vascular structures and epicardial fat thickness in young adults with CAH as a result of 21OHase deficiency. Correlations between the duration and dose of glucocorticoid therapy and cardiovascular parameters were analysed.

METHODS

This case-control study of young adults (18-31 years old) included 20 patients (5 men and 15 women) and 16 control subjects (8 men and 8 women). Echocardiographic analysis was performed using high-resolution ultrasound.

RESULTS

No ultrasonographic changes in any indices of myocardial function, vascular structures and epicardial fat thickness were found in patients, except for an impaired left ventricular end-diastolic diameter in female patients (28.1 ± 1.6 vs 26.0 ± 2.4 mm/m² , P = .021), compared with those in individuals in the control group. Nevertheless, the individual patient values were within the normal range. Multiple linear regression analysis in female patients demonstrated that an elevated daily dose of glucocorticoids correlated with increased indices of left ventricular posterior wall thickness (Partial r = 0.68, P = .007), left ventricular end-diastolic diameter (Partial r = 0.62, P = .017), aortic diameter (Partial r = 0.60, P = .022) and left carotid artery intima-media thickness (Partial r = 0.61, P = .021), independently of treatment duration.

CONCLUSION

No signs of cardiovascular dysfunction were observed in any patient. The daily dose of glucocorticoids may play a role in the mechanisms of some markers of cardiac hypertrophy, left ventricular and aortic dilation and subclinical atherosclerosis.

Bioelectrical Impedance Phase Angle and Its Determinants in Patients with Classic Congenital Adrenal Hyperplasia

BACKGROUND

Patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency (CAH21OHD) have increased fat mass and metabolic alterations. The bioelectrical impedance phase angle (PhA) is an indicator of cellular integrity in several diseases. This study aimed to determine the influence of adiposity levels, sex, CAH21OHD, pubertal development, body composition, and treatment on the PhA of patients with CAH21OHD.

METHODS

Forty girls and 30 boys with CAH21OHD aged 15.3 ± 5.8 years were evaluated. Sexual maturation was assessed by a pediatrician. The PhA was assessed using bioelectrical impedance, percentage of fat mass (% FM), and lean soft tissue (LST) with dual-energy X-ray absorptiometry. Adiposity levels were compared using % FM tertiles and body mass index (BMI). Glucocorticoid dosage was converted using hydrocortisone dose equivalent (HDE).

RESULTS

No differences were found in the PhA values among the clinical form (p = 0.103), BMI (p = 0.498), and % FM (p = 0.654) groups. High PhA values were observed in boys (p = 0.011) and postpubertal (p < 0.001) patients. LST, HDE, and height in girls (r² = 0.68, p < 0.001) and age, HDE, and FM in boys (r² = 0.82, p < 0.001) determined the PhA variations. BMI explained 14% (p = 0.032) of the PhA variations, whereas LST, height, HDE, and FM (kg) explained 66% (p < 0.001) in the prepubertal, pubertal, and postpubertal groups, respectively.

CONCLUSION

LST determined the PhA variations in girls and the postpubertal group. Age and BMI were determinants in boys and the pre- and pubertal groups, respectively.

Fat Distribution and Lipid Profile of Young Adults with Congenital Adrenal Hyperplasia Due to 21-Hydroxylase Enzyme Deficiency

We aimed to compare detailed fat distribution and lipid profile between young adults with congenital adrenal hyperplasia due to 21-hydroxylase enzyme deficiency and a control group. We also verified independent associations of treatment duration and daily hydrocortisone dose equivalent (HDE) with lipid profile within patients. This case-control study included 23 patients (7 male and 16 female) matched by an age range of young adults (18-31 years) with 20 control subjects (8 male and 12 female). Dual energy X-ray absorptiometry was used to measure the fat distribution. Male patients demonstrated elevated indices of fat mass for total (7.7 ± 2.1 vs. 4.5 ± 1.3 kg/m² , p = 0.003), trunk (4.0 ± 1.2 vs. 2.2 ± 0.8 kg/m² , p = 0.005), android (0.63 ± 0.24 vs. 0.32 ± 0.15 kg/m² , p = 0.008), gynoid (1.34 ± 0.43 vs. 0.74 ± 0.24 kg/m² , p = 0.005), arm (0.65 ± 0.16 vs. 0.39 ± 0.10 kg/m² , p = 0.009), and leg regions (2.7 ± 0.8 vs. 1.6 ± 0.4 kg/m² , p = 0.005) than the control group, but not in females. However, female patients demonstrated elevated ratio of low-density lipoprotein cholesterol to high-density lipoprotein cholesterol (1.90 ± 0.46 vs. 1.39 ± 0.47, p = 0.009) than the control group, but not in males. Total fat mass was inversely correlated with total testosterone (r = -0.64, p = 0.014) and positively correlated with leptin in males (r = 0.75, p = 0.002). An elevated daily HDE (β = 0.43, p = 0.038 and β = 0.47, p = 0.033) and trunk to total fat mass ratio (β = 0.46, p = 0.025, and β = 0.45, p = 0.037) were independently correlated with impaired lipid profile markers. Although there is no altered lipid profile, male patients demonstrated an increased fat distribution. However, female patients presented with an impaired lipid profile marker but demonstrated close values of normal fat distribution. Interestingly, the dose of glucocorticoid therapy can have some role in the lipid mechanisms.

EMQN best practice guidelines for molecular genetic testing and reporting of 21-hydroxylase deficiency

Molecular genetic testing for congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21-OHD) is offered worldwide and is of importance for differential diagnosis, carrier detection and adequate genetic counseling, particularly for family planning. In 2008 the European Molecular Genetics Quality Network (EMQN) for the first time offered a European-wide external quality assessment scheme for CAH (due to 21-OH deficiency). The interest was great and over the last years at about 60 laboratories from Europe, USA and Australia regularly participated in that scheme. These best practice guidelines were drafted on the basis of the extensive knowledge and experience got from those annually organized CAH-schemes. In order to obtain the widest possible consultation with practicing laboratories the draft was therefore circulated twice by EMQN to all laboratories participating in the EQA-scheme for CAH genotyping and was updated by that input. The present guidelines address quality requirements for diagnostic molecular genetic laboratories, as well as criteria for CYP21A2 genotyping (including carrier-testing and prenatal diagnosis). A key aspect of that article is the use of appropriate methodologies (e.g., sequencing methods, MLPA (multiplex ligation dependent probe amplification), mutation specific assays) and respective limitations and analytical accuracy. Moreover, these guidelines focus on classification of variants, and the interpretation and standardization of the reporting of CYP21A2 genotyping results. In addition, the article provides a comprehensive list of common as well as so far unreported CYP21A2-variants.

Novel non-classic CYP21A2 variants, including combined alleles, identified in patients with congenital adrenal hyperplasia

OBJECTIVE

Congenital adrenal hyperplasia (CAH) is an inborn error of metabolism and a common disorder of sex development where >90% of all cases are due to 21-hydroxylase deficiency. Novel and rare pathogenic variants account for 5% of all clinical cases. Here, we sought to investigate the functional and structural effects of four novel (p.Val358Ile, p.Arg369Gln, p.Asp377Tyr, and p.Leu461Pro) and three combinations of CYP21A2 variants (i.e. one allele containing two variants p.[Ile172Asn;Val358Ile], p.[Val281Leu;Arg369Gln], or p.[Asp377Tyr;Leu461Pro]) identified in patients with CAH.

METHODS

All variants were reconstructed by in vitro site-directed mutagenesis, the proteins were transiently expressed in COS-1 cells and enzyme activities directed toward the two natural substrates (17-hydroxyprogesterone and progesterone) were determined. In parallel, in silico prediction of the pathogenicity of the variants based on the human CYP21 X-ray structure was performed.

RESULTS

The novel variants, p.Val358Ile, p.Arg369Gln, p.Asp377Tyr, and p.Leu461Pro exhibited residual enzymatic activities within the range of non-classic (NC) CAH variants (40-82%). An additive effect on the reduction of enzymatic activity (1-17%) was observed when two variants were expressed together, as identified in several patients, resulting in either NC or more severe phenotypes. In silico predictions were in line with the in vitro data except for p.Leu461Pro.

CONCLUSIONS

Altogether, the combination of clinical data, in silico prediction, and data from in vitro studies are important for establishing a correct genotype and phenotype correlation in patients with CAH.

Clinical and molecular profile of newborns with confirmed or suspicious congenital adrenal hyperplasia detected after a public screening program implementation

OBJECTIVE

To describe the results obtained in a neonatal screening program after its implementation and to assess the clinical and molecular profiles of confirmed and suspicious congenital adrenal hyperplasia cases.

METHODS

A cross-sectional study was conducted. Newborns with suspected disease due to high 17-hydroxyprogesterone levels and adjusted for birth weight were selected. Classical congenital adrenal hyperplasia (salt-wasting and simple virilizing forms) was diagnosed by an increase in 17-hydroxyprogesterone levels as confirmed in the retest, clinical evaluation, and genotype determined by SNaPshot and multiplex ligation-dependent probe amplification.

RESULTS

After 24 months, 15 classic congenital adrenal hyperplasia cases were diagnosed in a total of 217,965 newborns, with an estimated incidence of 1:14,531. From 132 patients, seven non-classical and 14 heterozygous patients were screened for CYP21A2 mutations, and 96 patients presented false positives with wild type CYP21A2. On retest, increased 17-hydroxyprogesterone levels were found in classical congenital adrenal hyperplasia patients and showed significant correlation with genotype-related classical genital adrenal hyperplasia. The most frequent mutations were IVS2-13A/C>G followed by gene deletion or rearrangement events in the classical form. In non-classical and heterozygous diseases, p.Val282Leu was the most common mutation.

CONCLUSIONS

The results underscore the effectiveness of congenital adrenal hyperplasia neonatal screening in the public health system and indicate that the adopted strategy was appropriate. The second sample collection along with genotyping of suspected cases helped to properly diagnose both severe and milder cases and delineate them from false positive patients.

Prevalence of Testicular Adrenal Rest Tumor and Factors Associated with Its Development in Congenital Adrenal Hyperplasia

BACKGROUND

Testicular adrenal rest tumors (TART) can cause infertility in congenital adrenal hyperplasia (CAH) males.

AIMS

To determine TART prevalence in patients with CAH due to 21-hydroxylase deficiency (21-OHD) and evaluate possible factors associated with its development.

METHODS

This is a descriptive and analytical cross-sectional study evaluating males with the classical form of 21-OHD through testicular ultrasonography and serum inhibin B dosages. Data on prescribed glucocorticoid dose and serum levels of 17- hydroxyprogesterone (17-OHP), androstenedione (Andro), ACTH, renin, and LH were obtained from medical records.

RESULTS

Thirty-eight males were evaluated. The mean age on ultrasonography was 15.2 ± 6.7 (3-27) years. Nine patients (23.7%) had TART, 4 of them were prepubertal and the youngest was 5 years old. No association was found between TART and 21-OHD phenotype, glucocorticoid dose, or 17-OHP, ACTH, LH, renin, and inhibin B levels measured in the 6 preceding years. However, 50% of the patients who presented increased Andro 2 years prior to the evaluation had TART (p = 0.018, OR = 8.00 [95% CI: 1.42-44.92]), whereas in the normal Andro group only 16.7% had tumors.

CONCLUSION

This study showed that TART can occur in prepubertal patients and that disease control could be a factor associated with its development. Therefore, we suggest investigating TART development early in childhood, mainly in poorly controlled 21-OHD patients.

Development of CYP21A2 Genotyping Assay for the Diagnosis of Congenital Adrenal Hyperplasia

BACKGROUND

Steroid 21-hydroxylase deficiency due to CYP21A2 gene mutations represents more than 90% of all congenital adrenal hyperplasia cases. This deficiency is screened by measuring levels of 17-hydroxyprogesterone, which may vary, causing false positive or false negative results. In order to assist the diagnosis, molecular methodologies have been employed. This work aimed to perform genotyping assays to detect mutations in the CYP21A2 gene and compare the findings with other population studies.

METHODS

The SNaPshot assay was developed to simultaneously detect 12 frequent point mutations in the CYP21A2 gene (p.Arg409Cys, p.Gln319Ter, p.Arg357Trp, p.Leu308PhefsTer6, p.Val237Glu, IVS2-13A/C > G, p.Ile173Asn, p.Pro31Leu, p.Pro454Ser, p.Val282Leu, p.Gly111ValfsTer21 and p.His63Leu). The direct sequencing and multiplex ligation-dependent probe amplification assays were used to confirm point mutations present in the developed method. The latter was also used to search large deletions and gene conversion, complementing the investigation. A total of 166 cases were studied.

RESULTS

The SNaPshot assay was successfully developed to detect the 12 mutations. The results of mutation analysis indicated 84 pathogenic alleles in 48 cases, with p.Val282Leu (27.1%) and IVS2-13A/C > G (20.8%) being the most frequently found mutations. Between the findings of this study and those of other South American studies, there were significant differences in frequency for p.Pro31Leu and p.Val282Leu (p < 0.001). A new variant T in IVS2-13A/C > G was identified in two patients via the SNaPshot assay.

CONCLUSION

The molecular strategy developed for CYP21A2 gene mutation screening allowed us to detect the principle mutations described around the world. Furthermore, the first Southern Brazilian mutation frequencies concerning the CYP21A2 gene were obtained.

CYP21A2 mutation update: Comprehensive analysis of databases and published genetic variants

Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders of adrenal steroidogenesis. Disorders in steroid 21-hydroxylation account for over 95% of patients with CAH. Clinically, the 21-hydroxylase deficiency has been classified in a broad spectrum of clinical forms, ranging from severe or classical, to mild late onset or non-classical. Known allelic variants in the disease causing CYP21A2 gene are spread among different sources. Until recently, most variants reported have been identified in the clinical setting, which presumably bias described variants to pathogenic ones, as those found in the CYPAlleles database. Nevertheless, a large number of variants are being described in massive genome projects, many of which are found in dbSNP, but lack functional implications and/or their phenotypic effect. In this work, we gathered a total of 1,340 GVs in the CYP21A2 gene, from which 899 variants were unique and 230 have an effect on human health, and compiled all this information in an integrated database. We also connected CYP21A2 sequence information to phenotypic effects for all available mutations, including double mutants in cis. Data compiled in the present work could help physicians in the genetic counseling of families affected with 21-hydroxylase deficiency.

Functional analysis of human cytochrome P450 21A2 variants involved in congenital adrenal hyperplasia

Cytochrome P450 (P450, CYP) 21A2 is the major steroid 21-hydroxylase, converting progesterone to 11-deoxycorticosterone and 17α-hydroxyprogesterone (17α-OH-progesterone) to 11-deoxycortisol. More than 100 CYP21A2 variants give rise to congenital adrenal hyperplasia (CAH). We previously reported a structure of WT human P450 21A2 with bound progesterone and now present a structure bound to the other substrate (17α-OH-progesterone). We found that the 17α-OH-progesterone- and progesterone-bound complex structures are highly similar, with only some minor differences in surface loop regions. Twelve P450 21A2 variants associated with either salt-wasting or nonclassical forms of CAH were expressed, purified, and analyzed. The catalytic activities of these 12 variants ranged from 0.00009% to 30% of WT P450 21A2 and the extent of heme incorporation from 10% to 95% of the WT. Substrate dissociation constants (K_s) for four variants were 37-13,000-fold higher than for WT P450 21A2. Cytochrome b₅, which augments several P450 activities, inhibited P450 21A2 activity. Similar to the WT enzyme, high noncompetitive intermolecular kinetic deuterium isotope effects (≥ 5.5) were observed for all six P450 21A2 variants examined for 21-hydroxylation of 21-d₃-progesterone, indicating that C-H bond breaking is a rate-limiting step over a 10⁴-fold range of catalytic efficiency. Using UV-visible and CD spectroscopy, we found that P450 21A2 thermal stability assessed in bacterial cells and with purified enzymes differed among salt-wasting- and nonclassical-associated variants, but these differences did not correlate with catalytic activity. Our in-depth investigation of CAH-associated P450 21A2 variants reveals critical insight into the effects of disease-causing mutations on this important enzyme.

Neonatal 17-hydroxyprogesterone levels adjusted according to age at sample collection and birthweight improve the efficacy of congenital adrenal hyperplasia newborn screening

INTRODUCTION

The primary concern related to congenital adrenal hyperplasia (CAH) newborn screening (NBS) is the high rate of false-positive results (FPR) associated with prematurity; false-negative results (FNR) can also occur due to precocious sample collection.

OBJECTIVE

To determine the neonatal 17-hydroxyprogesterone (N17OHP) normal range in newborns in Sao Paulo using different references according to age and birthweight (BW) and to establish the optimal NBS cut-off levels.

METHODS

Neonatal 17-hydroxyprogesterone levels from 271 810 newborns (NBs) according to sample collection time (G1: 48-<72 h and G2: ≥72 h) and BW (≤1500 g, 1501-2000 g, 2001-2500 and >2500 g) were evaluated. N17OHP was measured by an fluoroimmunoassay, and serum 17OHP was measured by liquid chromatography-mass spectrometry. Affected and asymptomatic NBs with persistently increased 17OHP levels were submitted to CYP21A2-sequencing.

RESULTS

Neonatal 17-hydroxyprogesterone levels in G1 were lower than G2 in all BW groups (P < 0·001). The FPR rate in G1/G2 was 0·2% using the 99·8th and 0·5% using the 99·5th percentile. The 99·8th percentile N17OHP value was the best cut-off for distinguishing between unaffected and affected NBs. Forty-four salt wasters, and five simple virilisers were diagnosed; N17OHP levels ranged from 93·3 to 2209·8 nmol/l, and no affected neonates with FNR were identified. The positive predictive value in G1 and G2 using the 99·8th percentile was 5·6% and 14·1%, respectively, and 2·3% and 7%, respectively, using the 99·5th percentile. Molecular tests identified two NBs with the nonclassical form among the 29 FPR.

CONCLUSION

Neonatal 17-hydroxyprogesterone levels adjusted to sample collection age and birthweight reduced the FPR, and the use of N17OHP values based upon the 99·8th percentile improved the NBS efficacy.

Structure-based activity prediction of CYP21A2 stability variants: A survey of available gene variations

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency accounts for 90-95% of CAH cases. In this work we performed an extensive survey of mutations and SNPs modifying the coding sequence of the CYP21A2 gene. Using bioinformatic tools and two plausible CYP21A2 structures as templates, we initially classified all known mutants (n = 343) according to their putative functional impacts, which were either reported in the literature or inferred from structural models. We then performed a detailed analysis on the subset of mutations believed to exclusively impact protein stability. For those mutants, the predicted stability was calculated and correlated with the variant's expected activity. A high concordance was obtained when comparing our predictions with available in vitro residual activities and/or the patient's phenotype. The predicted stability and derived activity of all reported mutations and SNPs lacking functional assays (n = 108) were assessed. As expected, most of the SNPs (52/76) showed no biological implications. Moreover, this approach was applied to evaluate the putative synergy that could emerge when two mutations occurred in cis. In addition, we propose a putative pathogenic effect of five novel mutations, p.L107Q, p.L122R, p.R132H, p.P335L and p.H466fs, found in 21-hydroxylase deficient patients of our cohort.

Functional and Structural Consequences of Nine CYP21A2 Mutations Ranging from Very Mild to Severe Effects

We present the functional and structural effects of seven novel (p.Leu12Met, p.Arg16Cys, p.Ser101Asn, p.Ser202Gly, p.Pro267Leu, p.Gln389_Ala391del, and p.Thr450Met) and two previously reported but not studied (p.Ser113Phe and p.Thr450Pro) CYP21A2 mutations. Functional analyses were complemented with in silico prediction of mutation pathogenicity based on the recently crystallized human CYP21A2 structure. Mutated proteins were transiently expressed in COS-1 cells and enzyme activities towards 17-hydroxyprogesterone and progesterone were determined. Residual enzyme activities between 43% and 97% were obtained for p.Arg16Cys, p.Ser101Asn, p.Ser202Gly, p.Pro267Leu, and p.Thr450Met, similar to the activities of the well-known nonclassic mutations p.Pro453Ser and p.Pro482Ser, whereas the p.Leu12Met variant showed an activity of 100%. Conversely, the novel p.Ser113Phe, p.Gln389_Ala391del, and p.Thr450Pro mutations drastically reduced the enzyme function below 4%. The K_m values for all novel variants were in the same order of magnitude as for the wild-type protein except for p.The450Met. The maximum velocity was decreased for all mutants except for p.Leu12Met. We conclude that p.Leu12Met is a normal variant; the mutations p.Arg16Cys, p.Ser101Asn, p.Ser202Gly, p.Pro267Leu, and p.Thr450Met could be associated with very mild nonclassic CAH, and the mutations p.Ser113Phe, p.Gln389_Ala391del, and p.Thr450Pro are associated with classic CAH. The obtained residual activities indicated a good genotype-phenotype correlation.

Clinical profile and inheritance pattern of CYP21A2 gene mutations in patients with classical congenital adrenal hyperplasia from 10 families

CONTEXT

Congenital adrenal hyperplasia (CAH) is an autosomal recessive metabolic disorder caused by mutations in the CYP21A2 gene. Genetic diagnosis of 21-OH deficiency causing CAH is more complicated than any other monogenic disorder due to high variability of the locus. The disease has a wide spectrum of clinical variants making it difficult to establish a genotyp-phenotype correlation. Therefore, family studies are necessary to ascertain parental genotype and segregation of the mutant allele among the offspring.

AIM

The present study aimed to identify CYP21A2 gene mutations and analyze the segregation pattern in CAH trios (patients and their parents).

MATERIALS AND METHODS

A total of ten families having at least one CAH child were recruited.

RESULTS

Out of 31 children from ten families, 15 were affected with CAH and 13 of/them (12 females and 1 male) were available for genetic testing. One family had all the children affected with CAH. Compound heterozygous mutations were identified in seven patients (53.8%) whereas p.P30L, In2 and Δ8 bp mutations were present in homozygous state in three (23.1%), two (15.3 %) and one (7.6%) patient respectively.

CONCLUSIONS

In majority of the families, mutant alleles observed in the patients were inherited from the parents whereas three families showed sporadic mutations without any paternal or maternal origin. This indicated their novel occurrence due to misalignment of the parental genes and/or large deletion of the gene. Female preponderance was noted in the CAH families and also among the patients raising the possibility of survival advantage among females.

Human Cytochrome P450 21A2, the Major Steroid 21-Hydroxylase: STRUCTURE OF THE ENZYME·PROGESTERONE SUBSTRATE COMPLEX AND RATE-LIMITING C-H BOND CLEAVAGE

Cytochrome P450 (P450) 21A2 is the major steroid 21-hydroxylase, and deficiency of this enzyme is involved in ∼95% of cases of human congenital adrenal hyperplasia, a disorder of adrenal steroidogenesis. A structure of the bovine enzyme that we published previously (Zhao, B., Lei, L., Kagawa, N., Sundaramoorthy, M., Banerjee, S., Nagy, L. D., Guengerich, F. P., and Waterman, M. R. (2012) Three-dimensional structure of steroid 21-hydroxylase (cytochrome P450 21A2) with two substrates reveals locations of disease-associated variants. J. Biol. Chem. 287, 10613-10622), containing two molecules of the substrate 17α-hydroxyprogesterone, has been used as a template for understanding genetic deficiencies. We have now obtained a crystal structure of human P450 21A2 in complex with progesterone, a substrate in adrenal 21-hydroxylation. Substrate binding and release were fast for human P450 21A2 with both substrates, and pre-steady-state kinetics showed a partial burst but only with progesterone as substrate and not 17α-hydroxyprogesterone. High intermolecular non-competitive kinetic deuterium isotope effects on both kcat and kcat/Km, from 5 to 11, were observed with both substrates, indicative of rate-limiting C-H bond cleavage and suggesting that the juxtaposition of the C21 carbon in the active site is critical for efficient oxidation. The estimated rate of binding of the substrate progesterone (kon 2.4 × 10(7) M(-1) s(-1)) is only ∼2-fold greater than the catalytic efficiency (kcat/Km = 1.3 × 10(7) M(-1) s(-1)) with this substrate, suggesting that the rate of substrate binding may also be partially rate-limiting. The structure of the human P450 21A2-substrate complex provides direct insight into mechanistic effects of genetic variants.

In vitro functional studies of rare CYP21A2 mutations and establishment of an activity gradient for nonclassic mutations improve phenotype predictions in congenital adrenal hyperplasia

BACKGROUND

A detailed genotype-phenotype evaluation is presented by studying the enzyme activities of five rare amino acid substitutions (Arg233Gly, Ala265Ser, Arg341Trp, Arg366Cys and Met473Ile) identified in the CYP21A2 gene in patients investigated for Congenital adrenal hyperplasia (CAH).

OBJECTIVE

To investigate whether the mutations identified in the CYP21A2 gene are disease causing and to establish a gradient for the degree of enzyme impairment to improve prediction of patient phenotype.

DESIGN AND PATIENTS

The CYP21A2 genes of seven patients investigated for CAH were sequenced and five mutations were identified. The mutant proteins were expressed in vitro in COS-1 cells, and the enzyme activities towards the two natural substrates were determined to verify the disease-causing state of the mutations. The in vitro activities of these rare mutations were also compared with the activities of four mutations known to cause nonclassic CAH (Pro30Leu, Val281Leu, Pro453Ser and Pro482Ser) in addition to an in silico structural evaluation of the novel mutants.

MAIN OUTCOME MEASURE

To verify the disease-causing state of novel mutations.

RESULTS

Five CYP21A2 mutations were identified (Arg233Gly, Ala265Ser, Arg341Trp, Arg366Cys and Met473Ile). All mutant proteins exhibited enzyme activities above 5%, and four mutations were classified as nonclassic and one as a normal variant. By comparing the investigated protein changes with four common mutations causing nonclassic CAH, a gradient for the degree of enzyme impairment could be established. Studying rare mutations in CAH increases our knowledge regarding the molecular mechanisms that render a mutation pathogenic. It also improves phenotype predictions and genetic counselling for future generations.

Performance of phalangeal quantitative ultrasound parameters in the evaluation of reduced bone mineral density assessed by DX in patients with 21 hydroxylase deficiency

The purpose of this study was to verify the performance of quantitative ultrasound (QUS) parameters of proximal phalanges in the evaluation of reduced bone mineral density (BMD) in patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency (21 OHD). Seventy patients with 21 OHD (41 females and 29 males), aged between 6-27 y were assessed. The QUS measurements, amplitude-dependent speed of sound (AD-SoS), bone transmission time (BTT), and ultrasound bone profile index (UBPI) were obtained using the BMD Sonic device (IGEA, Carpi, Italy) on the last four proximal phalanges in the non-dominant hand. BMD was determined by dual energy X-ray (DXA) across the total body and lumbar spine (LS). Total body and LS BMD were positively correlated to UBPI, BTT and AD-SoS (correlation coefficients ranged from 0.59-0.72, p < 0.001). In contrast, when comparing patients with normal and low (Z-score < -2) BMD, no differences were found in the QUS parameters. Furthermore, UBPI, BTT and AD-SoS measurements were not effective for diagnosing patients with reduced BMD by receiver operator characteristic curve parameters. Although the AD-SoS, BTT and UBPI showed significant correlations with the data obtained by DXA, they were not effective for diagnosing reduced bone mass in patients with 21 OHD.

Functional studies of p.R132C, p.R149C, p.M283V, p.E431K, and a novel c.652-2A>G mutations of the CYP21A2 gene

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is the most frequent inborn error of metabolism and accounts for 90–95% of CAH cases. In the present work, we analyzed the functional consequence of four novel previously reported point CYP21A2 mutations -p.R132C, p.R149C, p.M283V, p.E431K- found in Argentinean 21-hydroxylase deficient patients. In addition, we report an acceptor splice site novel point mutation, c.652-2A>G, found in a classical patient in compound heterozygosity with the rare p.R483Q mutation. We performed bioinformatic and functional assays to evaluate the biological implication of the novel mutation. Our analyses revealed that the residual enzymatic activity of the isolated mutants coding for CYP21A2 aminoacidic substitutions was reduced to a lesser than 50% of the wild type with both progesterone and 17-OH progesterone as substrates. Accordingly, all the variants would predict mild non-classical alleles. In one non-classical patient, the p.E431K mutation was found in cis with the p.D322G one. The highest decrease in enzyme activity was obtained when both mutations were assayed in the same construction, with a residual activity most likely related to the simple virilizing form of the disease. For the c.652-2A>G mutation, bioinformatic tools predicted the putative use of two different cryptic splicing sites. Nevertheless, functional analyses revealed the use of only one cryptic splice acceptor site located within exon 6, leading to the appearance of an mRNA with a 16 nt deletion. A severe allele is strongly suggested due to the presence of a premature stop codon in the protein only 12 nt downstream.

Functional studies of novel CYP21A2 mutations detected in Norwegian patients with congenital adrenal hyperplasia

In about 95% of cases, congenital adrenal hyperplasia (CAH) is caused by mutations in CYP21A2 gene encoding steroid 21-hydroxylase (21OH). Recently, we have reported four novel CYP21A2 variants in the Norwegian population of patients with CAH, of which p.L388R and p.E140K were associated with salt wasting (SW), p.P45L with simple virilising (SV) and p.V211M+p.V281L with SV to non-classical (NC) phenotypes. We aimed to characterise the novel variants functionally utilising a newly designed in vitro assay of 21OH enzyme activity and structural simulations and compare the results with clinical phenotypes. CYP21A2 mutations and variants were expressed in vitro. Enzyme activity was assayed by assessing the conversion of 17-hydroxyprogesterone to 11-deoxycortisol by liquid chromatography tandem mass spectroscopy. PyMOL 1.3 was used for structural simulations, and PolyPhen2 and PROVEAN for predicting the severity of the mutants. The CYP21A2 mutants, p.L388R and p.E140K, exhibited 1.1 and 11.3% of wt 21OH enzyme activity, respectively, in vitro. We could not detect any functional deficiency of the p.P45L variant in vitro; although prediction tools suggest p.P45L to be pathogenic. p.V211M displayed enzyme activity equivalent to the wt in vitro, which was supported by in silico analyses. We found good correlations between phenotype and the in vitro enzyme activities of the SW mutants, but not for the SV p.P45L variant. p.V211M might have a synergistic effect together with p.V281L, explaining a phenotype between SV and NC CAH.

Leydig cell tumour in a 46,XX child with congenital adrenal hyperplasia due to 21-hydroxylase deficiency

A 10-year-old male was referred to our institution due to short stature and bilateral cryptorchidism and reported pubic hair development and acne since the age of 4 years. Laboratory and molecular genetic tests indicated congenital adrenal hyperplasia due to 21-hydroxylase deficiency. After treatment with prednisone, adrenal hormones normalised but testosterone remained elevated. Magnetic resonance imaging of the abdomen due to cryptorchidism revealed uterus and adnexal attachments, a prostate and poorly defined nodules on the iliac chains. Upon exploratory laparotomy, a hysterectomy, bilateral oophorectomy and resection of a peri-adnexal nodular lesion on the patient's right side were performed. Histopathology of the nodule mass was compatible with a Leydig cell tumour with a low proliferation rate according to Ki67.

Isolated p.H62L Mutation in the CYP21A2 Gene in a Simple Virilizing 21-Hydroxylase Deficient Patient

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency accounts for 90%–95% of cases. This autosomal recessive disorder has a broad spectrum of clinical forms, ranging from severe or classical, which includes the salt-wasting and simple virilizing forms, to the mild late onset or nonclassical form. Most of the disease-causing mutations described are likely to be the consequence of nonhomologous recombination or gene conversion events between the active CYP21A2 gene and its homologous CYP21A1P pseudogene. Nevertheless, an increasing number of naturally occurring mutations have been found. The change p.H62L is one of the most frequent rare mutations of the CYP21A2 gene. It was suggested that the p.H62L represents a mild mutation that may be responsible for a more severe enzymatic impairment when presented with another mild mutation on the same allele. In this report, a 20-year-old woman carrying an isolated p.H62L mutation in compound heterozygosity with c.283-13A/C>G mutation is described. Although a mildly nonclassical phenotype was expected, clinical signs and hormonal profile of the patient are consistent with a more severe simple virilizing form of 21-hydroxylase deficiency. The study of genotype-phenotype correlation in additional patients would help in defining the role of p.H62L in disease manifestation.

A unique case of female pseudohermaphroditism with 21-hydroxylase deficiency and small supernumerary marker chromosome 7

Small supernumerary marker chromosomes (sSMCs) are present in ~2.6x10⁶ individuals worldwide. Concerning their clinical consequences as well as their chromosomal origin and shape, sSMCs are a heterogeneous group of derivative chromosomes; 70% of sSMC carriers are clinically normal. In the present study, we report on a female with mosaicism (45%) of a de novo sSMC derived from chromosome 7, in which the observed clinical signs do not correspond to comparable cases in the literature. She is clinically normal apart from problems in gender determination, a uterus without ovaries and an external penis, pointing overall towards an adrenogenital syndrome (AGS). 21-Hydroxylase deficiency (21-OHD) is the most common cause of AGS. A corresponding analysis for underlying mutations in the CYP21A2 gene revealed a homozygous mutation c.518T>A (p.Ile173Asn) inherited from both non-related parents. Overall, in this study, we report a unique case of female pseudohermaphroditism, classified as a simple virilization form of 21-OHD having an additional minute-shaped chromosome 7 [min(7)(:p11.1->q11.23:)]. Notably, AGS was due to a mutation in the CYP21A2 gene located on chromosome 6. This is a further example that detection of an sSMC does not always resolve the clinical case.

Genotype-phenotype correlation in 1,507 families with congenital adrenal hyperplasia owing to 21-hydroxylase deficiency

Over the last two decades, we have extensively studied the genetics of congenital adrenal hyperplasia caused by 21-hydroxylase deficiency (CAH) and have performed 8,290 DNA analyses of the CYP21A2 gene on members of 4,857 families at risk for CAH--the largest cohort of CAH patients reported to date. Of the families studied, 1,507 had at least one member affected with one of three known forms of CAH, namely salt wasting, simple virilizing, or nonclassical CAH. Here, we report the genotype and phenotype of each affected patient, as well as the ethnic group and country of origin for each patient. We showed that 21 of 45 genotypes yielded a phenotypic correlation in our patient cohort. In particular, contrary to what is generally reported in the literature, we found that certain mutations, for example, the P30L, I2G, and I172N mutations, yielded different CAH phenotypes. In salt wasting and nonclassical CAH, a phenotype can be attributed to a genotype; however, in simple virilizing CAH, we observe wide phenotypic variability, particularly with the exon 4 I172N mutation. Finally, there was a high frequency of homozygous I2G and V281L mutations in Middle Eastern and Ashkenazi Jewish populations, respectively. By identifying the predominant phenotype for a given genotype, these findings should assist physicians in prenatal diagnosis and genetic counseling of parents who are at risk for having a child with CAH.

Accuracy of anthropometric measurements in estimating fat mass in individuals with 21-hydroxylase deficiency

OBJECTIVE

The use of anthropometric measurements to estimate the percentage of body fat (%BF) is easy and inexpensive. However, the accuracy of these methods in patients with 21-hydroxylase deficiency (21OHD) has not been explored. The objective of this study was to evaluate the accuracy of skinfold-based models, body mass index (BMI), and waist circumference (WC) in estimations of %BF using dual-energy X-ray absorptiometry (DXA) as the reference method in individuals with 21OHD.

METHODS

Fifty-four 21OHD patients (32 women and 22 men), aged 7 to 20 y, were recruited for the study. DXA was used to determine %BF; four predictive skinfold equations, BMI, and WC were assessed for accuracy in determining %BF.

RESULTS

All predictive skinfold equations were highly associated (R, range: 0.82-0.89) with DXA %BF values. In women, BMI and WC showed moderate correlations (R = 0.69 for both BMI and WC) with DXA values. In contrast, among men there was a low explanatory power for BMI (13%) and WC (4%) and high errors (BMI, 6.9%; WC, 7.4%). All predictive equations significantly underestimated %BF (range of differences, -4.1 to -8.9) compared with DXA (women, 31.3 ± 6.1; men, 24.4 ± 7.3), and large limits of agreement were observed (range, -15.3 to 1.7 and -15.5 to 4.2 for women and men, respectively).

CONCLUSION

In children and adolescents with 21OHD, %BF as estimated by skinfold measurements was associated more strongly with DXA-assessed %BF than both BMI and WC. However, still, the skinfold-based assessment underestimated DXA %BF and showed moderate agreement.

Metabolic evaluation of young women with congenital adrenal hyperplasia

OBJECTIVE: To evaluate insulin resistance and lipid profile in women with congenital adrenal hyperplasia (CAH) caused by classical 21-hydroxylase deficiency (21OHD), and their association with body mass index (BMI) and corticosteroid dosage. SUBJECTS AND METHODS: We assessed BMI, waist circumference, current glucocorticoid dosage, glucose, insulin and lipid profile in eighteen young women (mean ± SD, 19.3 ± 3.0 years) with 21OHD CAH. RESULTS: BMI was normal in 12 patients, 5 of them were overweight, and 1 was obese. Waist circumference was high in 7 patients. Fasting insulin and HOMA-IR were elevated in seven and eight patients, respectively. Total cholesterol and triglycerides were high in only two patients, and HDL-cholesterol was low in four. Insulin resistance was not associated with BMI, waist circumference or glucocorticoid dose. CONCLUSIONS: Young women with 21OHD CAH had infrequent dyslipidemia, but had a higher prevalence of insulin resistance and central obesity, that were independent of BMI or corticosteroid dosage.

Functional characterisation of the H365Y mutation of the 21-hydroxylase gene in congenital adrenal hyperplasia

The study subject was a 13 day-old boy admitted to hospital, with weight loss since birth. He presented with the vomiting and hypotension that are classical features of congenital adrenal hyperplasia (CAH). The most common type of CAH is an autosomal recessive disorder caused by mutations in the 21-hydroxylase (CYP21A2) gene. To examine the CYP21A2 gene, gene-specific PCR was carried out, followed by sequencing. The baby was shown to be a compound heterozygote H365Y/R356W for two CYP21A2 gene mutations each inherited from a different parent. One of the mutations has not previously been functionally characterised. The mutations were reconstructed in an expression plasmid and characterised in vitro after transient transfection into human embryonic kidney (HEK293T) and hepatoblastoma (C3A) cell lines followed by measurement of enzyme activity. The CYP21A2 H365Y mutant exhibited minimal 21-hydroxylase activity to convert 17-hydroxyprogesterone to 11-deoxycortisol or progesterone to 11-deoxycorticosterone. Western immunoblotting indicated that the H365Y enzyme was produced in more variable amounts than wild type; in particular, the H365Y mutant protein may be unstable and/or subject to a more rapid degradation by the human proteosome as well as catalytically inefficient. The double mutant genotype with a severe mutation on each allele is compatible with the clinical presentation.

Structure-based analysis of five novel disease-causing mutations in 21-hydroxylase-deficient patients

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is the most frequent inborn error of metabolism, and accounts for 90–95% of CAH cases. The affected enzyme, P450C21, is encoded by the CYP21A2 gene, located together with a 98% nucleotide sequence identity CYP21A1P pseudogene, on chromosome 6p21.3. Even though most patients carry CYP21A1P-derived mutations, an increasing number of novel and rare mutations in disease causing alleles were found in the last years. In the present work, we describe five CYP21A2 novel mutations, p.R132C, p.149C, p.M283V, p.E431K and a frameshift g.2511_2512delGG, in four non-classical and one salt wasting patients from Argentina. All novel point mutations are located in CYP21 protein residues that are conserved throughout mammalian species, and none of them were found in control individuals. The putative pathogenic mechanisms of the novel variants were analyzed in silico. A three-dimensional CYP21 structure was generated by homology modeling and the protein design algorithm FoldX was used to calculate changes in stability of CYP21A2 protein. Our analysis revealed changes in protein stability or in the surface charge of the mutant enzymes, which could be related to the clinical manifestation found in patients.

Comprehensive genetic analysis of 182 unrelated families with congenital adrenal hyperplasia due to 21-hydroxylase deficiency

BACKGROUND

Genetic analysis is commonly performed in patients with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency.

STUDY OBJECTIVE

The objective of the study was to describe comprehensive CYP21A2 mutation analysis in a large cohort of CAH patients.

METHODS

Targeted CYP21A2 mutation analysis was performed in 213 patients and 232 parents from 182 unrelated families. Complete exons of CYP21A2 were sequenced in patients in whom positive mutations were not identified by targeted mutation analysis. Copy number variation and deletions were determined using Southern blot analysis and PCR methods. Genotype was correlated with phenotype.

RESULTS

In our heterogeneous U.S. cohort, targeted CYP21A2 mutation analysis did not identify mutations on one allele in 19 probands (10.4%). Sequencing identified six novel mutations (p.Gln262fs, IVS8+1G>A, IVS9-1G>A, p.R408H, p.Gly424fs, p.R426P) and nine previously reported rare mutations. The majority of patients (79%) were compound heterozygotes and 69% of nonclassic (NC) patients were compound heterozygous for a classic and a NC mutation. Duplicated CYP21A2 haplotypes, de novo mutations and uniparental disomy were present in 2.7% of probands and 1.9 and 0.9% of patients from informative families, respectively. Genotype accurately predicted phenotype in 90.5, 85.1, and 97.8% of patients with salt-wasting, simple virilizing, and NC mutations, respectively.

CONCLUSIONS

Extensive genetic analysis beyond targeted CYP21A2 mutational detection is often required to accurately determine genotype in patients with CAH due to the high frequency of complex genetic variation.

Sequence analysis of CYP21A1P in a German population to aid in the molecular biological diagnosis of congenital adrenal hyperplasia

BACKGROUND

The high homology between the CYP21A2 (cytochrome P450, family 21, subfamily A, polypeptide 2) and CYP21A1P (cytochrome P450, family 21, subfamily A, polypeptide 1 pseudogene) genes is the major obstacle to risk-free genetic diagnosis of congenital adrenal hyperplasia, especially regarding the quantification of gene dosage. Because of the lack of a comprehensive study providing useful information about the detailed genetic structure of CYP21A1P, we used a large data set to analyze and characterize this pseudogene.

METHODS

We amplified and directly sequenced the CYP21A1P and CYP21A2 genes of 200 unrelated individuals. The resulting sequence data were aligned against the manually curated transcript ENST0000448314 from Havana/Vega matching to the genebuild ENSG00000198457; all differences were documented. Copy number was measured by multiplex ligation-dependent probe amplification when necessary.

RESULTS

We found that 40 potentially variable positions in CYP21A2 were conserved in CYP21A1P in all study participants. In addition, we detected 14 CYP21A1P variants that were not previously reported in either CYP21A2 or CYP21A1P. Unlike CYP21A2, CYP21A1P possessed certain mutation haplotypes.

CONCLUSIONS

The genetic structure of CYP21A1P and the potential risks of false conclusions it may introduce are essential considerations in designing a PCR-based diagnosis procedure for congenital adrenal hyperplasia.

Novel deletion alleles carrying CYP21A1P/A2 chimeric genes in Brazilian patients with 21-hydroxylase deficiency

BACKGROUND

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency is caused by deletions, large gene conversions or mutations in CYP21A2 gene. The human gene is located at 6p21.3 within a locus containing the genes for putative serine/threonine Kinase RP, complement C4, steroid 21-hydroxylase CYP21 tenascin TNX, normally, in a duplicated cluster known as RCCX module. The CYP21 extra copy is a pseudogene (CYP21A1P). In Brazil, 30-kb deletion forming monomodular alleles that carry chimeric CYP21A1P/A2 genes corresponds to ~9% of disease-causing alleles. Such alleles are considered to result from unequal crossovers within the bimodular C4/CYP21 locus. Depending on the localization of recombination breakpoint, different alleles can be generated conferring the locus high degree of allelic variability. The purpose of the study was to investigate the variability of deleted alleles in patients with 21-hydroxylase deficiency.

METHODS

We used different techniques to investigate the variability of 30-kb deletion alleles in patients with 21-hydroxylase deficiency. Alleles were first selected after Southern blotting. The composition of CYP21A1P/A2 chimeric genes was investigated by ASO-PCR and MLPA analyses followed by sequencing to refine the location of recombination breakpoints. Twenty patients carrying at least one allele with C4/CYP21 30-kb deletion were included in the study.

RESULTS

An allele carrying a CYP21A1P/A2 chimeric gene was found unusually associated to a C4B/C4A Taq I 6.4-kb fragment, generally associated to C4B and CYP21A1P deletions. A novel haplotype bearing both p.P34L and p.H62L, novel and rare mutations, respectively, was identified in exon 1, however p.P30L, the most frequent pseudogene-derived mutation in this exon, was absent. Four unrelated patients showed this haplotype. Absence of p.P34L in CYP21A1P of normal controls indicated that it is not derived from pseudogene. In addition, the combination of different approaches revealed nine haplotypes for deleted 21-hydroxylase deficiency alleles.

CONCLUSIONS

This study demonstrated high allelic variability for 30-kb deletion in patients with 21-hydroxylase deficiency indicating that a founder effect might be improbable for most monomodular alleles carrying CYP21A1P/A2 chimeric genes in Brazil.

Composição corporal em mulheres com deficiência da 21-hidroxilase: comparação dos métodos antropométricos e de impedância bioelétrica em relação a um grupo controle

OBJETIVO: Estimar a composição corporal avaliada pela espessura de dobras cutâneas (EDC) e pela impedância bioelétrica (BIA) em um grupo de mulheres com hiperplasia adrenal congênita, forma clássica por deficiência da enzima 21-hidroxilase (HAC-C-D21OH) e em relação ao um grupo controle. PACIENTES E MÉTODOS: Foram avaliadas 16 pacientes com HAC-C-D21OH e 26 controles, todas do sexo feminino, com idades de 8 a 18 anos. Foram estimadas as massas gorda (MG) e magra (MM) utilizando EDC e BIA. Os dados das MG e MM foram analisados de forma relativa (%), absoluta (kg) e em relação à estatura (IMG e IMM). RESULTADOS: Não foram encontradas diferenças significativas entre os dois métodos em cada grupo avaliado. Em relação ao grupo controle, as pacientes com HAC-C-D21OH apresentaram valores maiores de MG (%) BIA, IMG BIA e IMM EDC e menores de MM (%) BIA. Foi verificada correlação positiva e alta em todos os parâmetros analisados. CONCLUSÃO: Os resultados observados pelos métodos de EDC e BIA foram semelhantes nesta amostra de mulheres com HAC-CD21OH, porém controversos em relação ao grupo controle, sugerindo que se tenha cautela no uso desses métodos de avaliação da composição corporal nessa população.

Phenotype-genotype correlations of 13 rare CYP21A2 mutations detected in 46 patients affected with 21-hydroxylase deficiency and in one carrier

CONTEXT

Steroid 21-hydroxylase deficiency is the most common enzymatic defect causing congenital adrenal hyperplasia with genotype/phenotype relationships for common mutations. Novel mutations of the CYP21A2 gene must be well studied to propose right genetic counseling for patients.

OBJECTIVE

Thirteen CYP21 mutations have been studied. A detailed description of phenotype was performed for all mutations (p.I77T, p.L167P, p.I230T, p.R233K, p.G291S, p.G292D, p.E320K, p.R341P, p.R354H, p.R369W, p.R408C, p.G424S, and p.R426H). In vitro and in silico studies were performed only for those not previously described (p.L167P, p.I230T, p.R233K, p.G292D, p.E320K, and p.R369W).

RESULTS

Regarding phenotype, patients with 10 of these mutations had a classical form. A patient with isolated p.I230T presented with nonclassical form and a patient with the association p.I230T + p.V281L in cis presented with a more severe phenotype. The p.R233K mutation was detected in a carrier partner. A patient with p.R369W presented with an intermediate form. Functional studies showed that all mutations except p.I230T and p.R369W decreased enzyme activity more than p.P30L: severity of p.R369W was intermediate between p.P30L and p.V281L, and finally p.I230T was less severe than p.V281L. Mutation analysis in a three-dimensional model structure of the CYP21 protein explained the observed in vitro effects, severe mutations being implicated in important functional domains of the protein.

CONCLUSION

According to phenotype and functional studies, 11 of the mutations described, except the isolated p.R369W and p.I230T, may be responsible for a severe phenotype underlying the necessity to manage children having them. The p.I230T is a nonclassical mutation, and for the p.R369W, we need more cases to precise its severity.

A p.P30L Mutation at the CYP21A2 Gene in Macedonian Patients with Nonclassical Congenital Adrenal Hyperplasia

Nonclassical congenital adrenal hyperplasia (NCAH) is an autosomal recessive imbalance in cortisol synthesis with adrenal androgen excess. Although rarely recognized in infants, it may cause premature adrenarche and pubarche, virilization in young women and variable symptoms in young men. It is commonly caused by mutations in CYP21A2, the gene for steroid 21-hydroxylase. Patients with the p.P30L allele tend to have pronounced evidence of androgen excess but are categorized as nonclassical. We used direct molecular detection of the p.P30L mutation in CYP21A2 in 11 Macedonian NCAH patients and in 17 members of their families using polymerase chain reaction/amplification created restriction site (PCR/ACRS) analysis and digestion with restriction enzymes. The p.P30L mutation was found in a homozygous state in seven (63.6%) and in a heterozygous state in four (36.4%) patients. Of the latter, one was also heterozygous for the p.Q318X mutation. The p.P30L mutation was found in a heterozygous state in 10 (58.8%) and in a homozygous state in one (5.9%) of the family members. These findings support a role of the p.P30L mutation in NCAH.

Functional analysis of two rare CYP21A2 mutations detected in Italian patients with a mildest form of congenital adrenal hyperplasia

BACKGROUND

More than 90% of all cases of congenital adrenal hyperplasia (CAH) result from steroid 21-hydroxylase gene (CYP21A2) mutations. Most of these mutations result from intergenic recombinations between CYP21A2 and closely linked CYP21A1P pseudogene. Rare mutations not generated by gene conversion account for 5-10% of 21-hydroxylase deficiency alleles.

OBJECTIVE

Functional analysis of two novel CYP21A2 missense mutations (p.R224W and p.D407N) was performed.

DESIGN

Our study was composed of two Italian patients suffering from a very mild form of nonclassic CAH (NC-CAH). To assay the enzymatic activity of mutants, the in vitro analysis was performed in transiently transfected COS-1 cells.

RESULTS

The residual activities obtained for p.R224W and p.D407N mutants allow their classification as NC-CAH mutations. These results correlate with the rate of severity of the patients' disease.

CONCLUSIONS

In this paper, we report two novel CYP21A2 mutations in two Italian individuals affected by 21-hydroxylase deficiency. Based on the functional in vitro analysis we can classify these mutations as NC-CAH variants.