Structure-phenotype correlations of human CYP21A2 mutations in congenital adrenal hyperplasia

Genetics of 21-OH Deficiency and Genotype-Phenotype Correlation: Experience of the Hellenic National Referral Center

21-hydroxylase deficiency (21-OHD) represents the most common form of congenital adrenal hyperplasia (CAH) due to CYP21A2 gene pathogenic variants. Τhe aim of this study was the identification of CYP21A2 variants in 500 subjects of Greek origin with a suspicion of 21-OHD and, by using the existing hormonal assessment and genotypes of the 500 subjects tested, to identify a biomarker that could differentiate between the heterozygotes and the cases with no pathogenic variants identified. Five hundred subjects with clinical suspicion of 21-OHD underwent CYP21A2 gene sequencing and Multiplex Ligation Dependent Probe Amplification (MLPA). Genetic diagnosis was achieved in 27.4% of the subjects tested, most of which presented with the non-classic form (NC) of 21-OHD. Heterozygotes accounted for 42.6% of cases, whereas no pathogenic variants were identified in 27% of cases. De novo aberrations, duplications, and five novel variants were also identified. Statistical analysis revealed that the difference between the basal and 60' post-ACTH stimulation 17-hydroxyprogesterone concentrations (Δ17-OHP60-0) could be a potential biomarker (p < 0.05) distinguishing the heterozygotes from the cases with no pathogenic variants identified, although no clear cut-off value could be set. Further analysis revealed overlapping clinical manifestations among all the subjects tested. The presented phenotypic traits of the subjects tested and the inability to identify a discriminative biochemical marker highlight the importance of comprehensive CYP21A2 genotyping to ascertain the correct genetic diagnosis and proper genetic counselling.

Design and synthesis of phosphoryl-substituted steroidal pyridazines (Pho-STPYRs) as potent estrogen receptor alpha inhibitors: targeted treatment of hormone-dependent breast cancer cells

Estrogen receptor alpha (ERα) is an important target for the discovery of new therapeutic drugs against hormone-dependent breast cancer. A series of phosphoryl-substituted steroidal pyridazines (Pho-STPYRs) were synthesized and biologically evaluated as potent ERα inhibitors. Pho-STPYRs showed cytotoxicity against breast cancer cells with IC50 values of 5.9 μM and higher. Pho-STPYRs 33 and 34 [IC50 (MCF7) = 6.5 and 5.9 μM, respectively] were found to block the expression of ERα, the main driver of breast cancer growth, and modulate the ERK, cyclin D1, and CDK4 pathways. Compound 34 showed selectivity, anti-estrogenic potency and high antiproliferative efficacy in combination with the AKT inhibitor. Molecular docking was used to more accurately define the binding mode of lead compounds 33 and 34 to ERα. The selectivity analysis showed that lead compounds 33 and 34 produce no effects on cytochromes P450, including CYP7A1, CYP7B1, CYP17A1, CYP19A1, and CYP21A2. In a word, Pho-STPYRs 33 and 34 are promising ERα inhibitors for the treatment of hormone-dependent breast cancer.

Exploration and biological evaluation of 20-vinyl pregnenes: A step forward toward selective modulators of the estrogen receptor α signaling for breast cancer treatment

A series of D-ring modified steroids bearing a vinyl ketone pendant were synthesized and evaluated for antiproliferative activity against breast cancer cell line and cytochromes P450. The lead compound, 21-vinyl 20-keto-pregnene (2f) (IC50 = 2.4 µM), was shown to be a promising candidate for future anticancer drug design, particularly against estrogen receptor α (ERα)-positive breast cancer. The lead compound was found to have a significant effect on the signaling pathways in parental and 4-hydroxytamoxifen-resistant cells. Compound 2f modulated the ERK, cyclin D1, and CDK4 pathways and blocked the expression of ERα, the main driver of breast cancer growth. Compound 2f significantly reduced 17β-estradiol-induced progesterone receptor expression. Accumulation of cleaved poly(ADP-ribose) polymerase in cells treated with compound 2f indicated induction of apoptosis. The selectivity analysis showed that lead compound 2f produces no significant effects on cytochromes P450, CYP19A1, CYP21A2, and CYP7B1.

A Humanized and Viable Animal Model for Congenital Adrenal Hyperplasia-CYP21A2-R484Q Mutant Mouse

Congenital Adrenal Hyperplasia (CAH) is an autosomal recessive disorder impairing cortisol synthesis due to reduced enzymatic activity. This leads to persistent adrenocortical overstimulation and the accumulation of precursors before the blocked enzymatic step. The predominant form of CAH arises from mutations in CYP21A2, causing 21-hydroxylase deficiency (21-OHD). Despite emerging treatment options for CAH, it is not always possible to physiologically replace cortisol levels and counteract hyperandrogenism. Moreover, there is a notable absence of an effective in vivo model for pre-clinical testing. In this work, we developed an animal model for CAH with the clinically relevant point mutation p.R484Q in the previously humanized CYP21A2 mouse strain. Mutant mice showed hyperplastic adrenals and exhibited reduced levels of corticosterone and 11-deoxycorticosterone and an increase in progesterone. Female mutants presented with higher aldosterone concentrations, but blood pressure remained similar between wildtype and mutant mice in both sexes. Male mutant mice have normal fertility with a typical testicular appearance, whereas female mutants are infertile, exhibit an abnormal ovarian structure, and remain in a consistent diestrus phase. Conclusively, we show that the animal model has the potential to contribute to testing new treatment options and to prevent comorbidities that result from hormone-related derangements and treatment-related side effects in CAH patients.

Approaching fertility in congenital adrenal hyperplasia: exploring P30L mutation-induced 21-hydroxylase deficiency with a presentation between non-classical and simple virilizing phenotypes. A case report

Congenital adrenal hyperplasia (CAH) is determined in the vast majority of cases by mutations in the CYP21A2 gene, which cause the deficiency of the 21 hydroxylase enzyme, which is involved in the synthesis of cortisol and aldosterone. Generally, CAH phenotype and disease severity can be predicted with the genotypes and is related to the residual activity of 21 hydroxylase enzyme. It is divided into classical CAH with salt wasting and simple virilizing forms and non-classical or late-onset CAH forms, respectively. Patients with 21 hydroxylase deficiency, including those with non-classic forms face immense challenges to their fertility. Glucocorticoid therapy has been shown to be useful in obtaining and maintaining a pregnancy among these patients, but it must be used with caution. Given the relevance of CAH in reproductive medicine as well as the diagnostic challenges posed by the phenotypic overlap with polycystic ovary syndrome and by overlap of its own phenotypes (classic CAH-nonclassic CAH), we present the case of a woman with CAH due to 21 hydroxylase deficiency caused by the P30L mutation with a clinical and biochemical presentation between the non-classical form and the classic simple virilizing form. Further, the successful fertility management in this patient and an overview of fertility management in CAH is depicted, as well.

Identifying the First Val281L Mutation Causing Nonclassic Congenital Adrenal Hyperplasia in the Central-East Region of Tunisia

Nonclassic congenital adrenal hyperplasia (NCAH) is a genetic disorder characterized by mutations in the genes encoding enzymes involved in cortisol production, most commonly the 21-hydroxylase enzyme. Unlike classic congenital adrenal hyperplasia (CAH), NCAH typically presents later in life with milder symptoms. The diagnosis of NCAH can be challenging due to its nonspecific symptoms and variable presentation. Early detection is crucial for timely intervention and management, particularly in families with a history of the condition. We report a case of NCAH in a patient from the Central-East Region of Tunisia, in whom the subsequent genetic testing revealed a Val281Leu (V281L) mutation in the CYP21A2 gene. A 26-year-old female presented with facial hirsutism and irregular menstrual cycles. Physical examination revealed mild hirsutism and laboratory tests showed elevated levels of testosterone and 17-hydroxyprogesterone (17-OHP). A provisional diagnosis of NCAH was made, subsequently confirmed by an adrenocorticotropic hormone (ACTH) stimulation test demonstrating an exaggerated 17-OHP response. Genetic testing revealed heterozygosity for the V281L mutation. Family testing showed the patient's mother to be homozygous and the father heterozygous for the mutation. This report highlights the importance of recognizing subtle symptoms of NCAH for early diagnosis and management. Genetic testing aids in confirming the diagnosis and identifying carriers within families. Treatment with glucocorticoids aims to suppress adrenal androgen production and manage symptoms. Regular follow-up is essential to monitor treatment response and adjust medication as needed. NCAH can present with subtle symptoms, necessitating a high index of suspicion for a proper diagnosis. Genetic testing plays a crucial role in confirming the diagnosis and identifying carriers within families. Early intervention and regular follow-up improve outcomes in affected individuals. This report also underscores the significance of genetic testing in the management of NCAH and highlights the need for increased awareness about this condition among healthcare providers.

Genotyping in patients with congenital adrenal hyperplasia by sequencing of newborn bloodspot samples

OBJECTIVES

Genotype-phenotype correlation in congenital adrenal hyperplasia (CAH) caused by 21-hydroxylase deficiency ranges from 45 to 97 %. We performed massively parallel sequencing of CYP21A2 on stored newborn bloodspot samples to catalogue the genotypes present in our patients with CAH and enable genotype-phenotype comparison.

METHODS

Participants ≤15 years old with clinically diagnosed CAH were recruited from The Sydney Children's Hospitals Network. Phenotype was classified from clinical and biochemical details in the medical record as salt wasting (SW), simple virilising (SV), non-classic (NC) or an intermediate phenotype (SW/SV; SV/NC). Amplicon-based sequencing for CYP21A2 was performed on stored newborn bloodspot samples by the New South Wales Newborn Bloodspot Screening Laboratory on MiSeq™Dx (Illumina, California). Available genetic test results were also obtained from the medical records.

RESULTS

Samples from 67 participants (43 % female, age 0.3-15 years) were sequenced, including 9 sibships. SW phenotype was present in 33/67 participants (49 %), SV in 9 (13 %) and NC in 16 (24 %). Intermediate phenotypes included SW/SV in seven participants (10 %) and SV/NC in two (3 %). Variants were identified in 90/116 alleles (78 %). A complete genotype was available in 47/67 participants (70 %). The most common genotype was homozygous c.293-13A/C>G (I2G) in 7/47 participants (15 %). Genotype correlated with the most commonly reported phenotype in 36/44 cases (82 %). Correlation was higher in SW and NC phenotypes.

CONCLUSIONS

This study uses genetic testing of newborn bloodspots to identify and characterise the genotypes present in an ethnically diverse Australian population with CAH. It further strengthens our knowledge of genotype-phenotype correlations in CAH.

Hormonal control during infancy and testicular adrenal rest tumor development in males with congenital adrenal hyperplasia: a retrospective multicenter cohort study

IMPORTANCE

Testicular adrenal rest tumors (TARTs), often found in male patients with congenital adrenal hyperplasia (CAH), are benign lesions causing testicular damage and infertility. We hypothesize that chronically elevated adrenocorticotropic hormone exposure during early life may promote TART development.

OBJECTIVE

This study aimed to examine the association between commencing adequate glucocorticoid treatment early after birth and TART development.

DESIGN AND PARTICIPANTS

This retrospective multicenter (n = 22) open cohort study collected longitudinal clinical and biochemical data of the first 4 years of life using the I-CAH registry and included 188 male patients (median age 13 years; interquartile range: 10-17) with 21-hydroxylase deficiency (n = 181) or 11-hydroxylase deficiency (n = 7). All patients underwent at least 1 testicular ultrasound.

RESULTS

TART was detected in 72 (38%) of the patients. Prevalence varied between centers. When adjusted for CAH phenotype, a delayed CAH diagnosis of >1 year, compared with a diagnosis within 1 month of life, was associated with a 2.6 times higher risk of TART diagnosis. TART onset was not predicted by biochemical disease control or bone age advancement in the first 4 years of life, but increased height standard deviation scores at the end of the 4-year study period were associated with a 27% higher risk of TART diagnosis.

CONCLUSIONS AND RELEVANCE

A delayed CAH diagnosis of >1 year vs CAH diagnosis within 1 month after birth was associated with a higher risk of TART development, which may be attributed to poor disease control in early life.

Discovery of highly potent proapoptotic antiestrogens in a series of androst-5,16-dienes D-modified with imidazole-annulated pendants

Heterocyclic derivatives of steroid hormones are potent anticancer agents, which are used in the chemotherapy of breast and prostate cancers. Here, we describe a novel series of androstenes, D-modified with imidazole-annulated pendants, with significant anticancer activity. Novel C17-linked imidazole-annulated heterocyclic derivatives of dehydropregnenolone acetate were synthesized by the cyclocondensation with amidines using 3β-acetoxy-21-bromopregna-5,16-dien-20-one as the substrate. The antiproliferative potency of all the synthesized compounds was evaluated against human prostate (22Rv1) and human breast (MCF7) cancer cell lines and cytochromes P450. The lead compound, imidazo[1,2-a]pyridine derivative 3h, was revealed to be a promising candidate for future anticancer drug design, particularly against ERα-positive breast cancer. Lead compound 3h was found to be selective against MCF7 cells with IC₅₀ of 0.1μM and to act as both a potent selective agent blocking estrogen receptor α, which is involved in the stimulation of breast cancer growth, and an effective apoptosis inducer. The potential ability of compound 3h to bind to ERα was studded using molecular docking and molecular dynamics simulation. The selectivity analysis showed that lead steroid 3h produces no effects on cytochromes P450 CYP17A1, CYP7A1, and CYP21A2.

Nonclassic Adrenal Hyperplasia (NCAH) due to 21-hydroxylase deficiency: A cohort of 78 patients

Diagnosis of nonclassic adrenal hyperplasia (NCAH) due to 21-hydroxylase deficiency (21-OHD) may be challenging due to its occult manifestations. To characterize clinical and molecular features of NCAH patients due to 21-hydroxylase deficiency, we retrospectively included 78 NCAH patients. Their phenotype and genotype were presented and compared. The transcription activities of novel CYP21A2 promoter variants were investigated using a dual-reporter luciferase assay system. This cohort included 53 females (68 %) and 25 males (32 %). The median of onset age was 13 years old (female: 13 range from 7 to 38; male: 11 range from 6 to 71). Menstrual cycle disorder was the most common complaint in females (62 %, n = 33) and for males, it was adrenal incidentalomas (52 %, n = 13). A total of 17 (22 %) patients complained of infertility. The most frequently variant was p.Ile173Asn (20 %, n = 31). Importantly, five variants in the promoter region including - 103/- 126 and - 196/- 296 were found in 21 (27 %) patients. Patients with promoter variants showed older onset age and less impaired hormone levels of 17-hydroxyprogesterone, ACTH, progesterone, and androstenedione. Compared with the wild-type promoter, the basic transcription activity of - 103/- 126 and - 196/- 296 promoter variants were reduced by 57% and 25%, respectively. Therefore, females with menstrual cycle disorders or infertility and males with adrenal incidentaloma should be considered of NCAH due to 21-OHD. When genotyping patients with NCAH, the promoter region of the CYP21A2 gene should be also investigated.

Rare combination of simple virilizing form of 21-hydroxylase deficiency, Graves' disease and 47, XXX in a woman: A case report

RATIONALE

Coexistence of congenital adrenal hyperplasia due to 21-hydroxylase deficiency, Graves' disease and 47, XXX is rare. We report a case of a 25-year-old woman presented with masculine appearance, hirsutism and enlarged clitoris. Lab tests showed elevated serum 17 hydroxyprogesterone, testosterone, dehydroepiandrosterone. Gene test revealed heterozygous gene mutation in CYP21A2:NM_000500:exon4:c.518 T > A, NM_000500:exon8:c.C1024T. Karyotype analysis showed 47, XXX. After prednisone replacement and antithyroid therapy, she got a normal menstruation and normal level of testosterone. These findings demonstrate that patients with abnormal chromosome are likely to combine 21-hydroxylase deficiency (21-OHD), thus karyotyping test should not be neglected for those who have been already diagnosed as 21-OHD. Additionally, chromosomal abnormality such as 47, XXX and Turner syndrome had susceptibility to develop autoimmune thyroid disease because a gene on X chromosome may be responsible for the occurrence of autoimmune thyroid disease. Moreover, both 21-OHD and Graves' disease (GD) can lead to high level of testosterone, thus we should keep in mind to test chromosome and thyroid function in 21-OHD patients to avoid misdiagnose or missed diagnosis. To the best of our knowledge, this is the first report of simple virilizing (SV) 21-OHD patient combined with 47, XXX and Graves disease.

PATIENT CONCERNS

A 24-years-old female of Han ethnicity was admitted to the endocrinology department complaining of absence of menses for half a year. The patient didn't noticed her enlarged clitoris until she was 17 years old. Her menarche was 16 years old and the final height was 163 centimeter. She was diagnosed with GD 2 months before admission to our hospital due to palpitation, heat intolerance, muscle weakness.

DIAGNOSES

The patient was diagnosed with SV 21-OHD, Graves disease and 47, XXX.

INTERVENTIONS

At first, the patient was given 10 mg methimazole twice a day as well as 5 mg predisone in the morning and 2.5 mg in the evening. After a year of regular medication and reexamination, she got a regular menstruation and thyroid function and now is taking 2.5 mg prednisone twice a day.

OUTCOMES

The patient got a regular menstruation and thyroid function. Laboratory results showed: testosterone declined to 0.1nmol/L (0.1-1.67nmol/L) and 17 hydroxyprogesterone get back to normal level: 1.01ng/ml (0.30-2.34ng/mL). However, her enlarged clitoris has not narrowed.

LESSONS

Patients with abnormal chromosome are likely to combine 21-OHD, thus karyotyping test should not be neglected for those who have been already diagnosed as 21-OHD. Additionally, chromosomal abnormality such as 47, XXX and Turner syndrome had susceptibility to develop autoimmune thyroid disease because a gene on X chromosome may be responsible for the occurrence of autoimmune thyroid disease. Moreover, both 21-OHD and GD can lead to high level of testosterone, thus we should keep in mind to test chromosome and thyroid function in 21-OHD patients to avoid misdiagnose or missed diagnosis. To the best of our knowledge, this is the first report of SV 21-OHD patient combined with 47, XXX and Graves disease.

Genetic analysis and novel variation identification in Chinese patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency

Congenital adrenal hyperplasia owing to 21-hydroxylase deficiency is an autosomal-recessive disorder caused by mutations in the CYP21A2 gene. The aim of the study was to analyze the molecular data of 155 21-OHD patients and retrospectively investigated the common allelic mutations of CYP21A2 in 1442 Chinese 21-OHD patients. Clinical features and mutations of CYP21A2 gene in 155 unrelated 21-OHD patients were examined. Of the 155 patients, 103 cases were salt-wasting (SW) forms, 38 were simple virilizing (SV) forms and 14 were non-classical (NC) forms. In general, two types of mutations including common allelic mutations (281/310, 90.6%) and rare mutations (29/310, 9.4%) were detected, among them four novel variants c.835G>T, c.1081C>T, c.1423C>T and c.651 + 2 T > G were identified. In 1442 Chinese 21-OHD patients, the most frequently mutations were I2G (36.2%), large deletion/conversion (20.7%) and p.I173N (17.8%), while p.V282L has the lowest frequency. In this study, we provided detailed clinical data and mutation spectrum in Chinese 21-OHD patients. Moreover, four novel CYP21A2 variants (c.835G>T, c.1081C>T, c.1423C>T and c.651 +2 T > G) were identified and computational structural modeling indicated that these novel variations probably affect structural stability. Our findings improve the understanding of CYP21A2 mutational spectrum and contribute to the precise diagnosis and prenatal counseling.

Evolution of genes involved in the unusual genitals of the bear macaque, Macaca arctoides

Genital divergence is thought to contribute to reproductive barriers by establishing a “lock‐and‐key" mechanism for reproductive compatibility. One such example, Macaca arctoides, the bear macaque, has compensatory changes in both male and female genital morphology as compared to close relatives. M. arctoides also has a complex evolutionary history, having extensive introgression between the fascicularis and sinica macaque species groups. Here, phylogenetic relationships were analyzed via whole‐genome sequences from five species, including M. arctoides, and two species each from the putative parental species groups. This analysis revealed ~3x more genomic regions supported placement in the sinica species group as compared to the fascicularis species group. Additionally, introgression analysis of the M. arctoides genome revealed it is a mosaic of recent polymorphisms shared with both species groups. To examine the evolution of their unique genital morphology further, the prevalence of candidate genes involved in genital morphology was compared against genome‐wide outliers in various population genetic metrics of diversity, divergence, introgression, and selection, while accounting for background variation in recombination rate. This analysis identified 67 outlier genes, including several genes that influence baculum morphology in mice, which were of interest since the bear macaque has the longest primate baculum. The mean of four of the seven population genetic metrics was statistically different in the candidate genes as compared to the rest of the genome, suggesting that genes involved in genital morphology have increased divergence and decreased diversity beyond expectations. These results highlight specific genes that may have played a role in shaping the unique genital morphology in the bear macaque.

CYP21A2 gene expression in a humanized 21-hydroxylase mouse model does not affect adrenocortical morphology and function

Steroid 21-hydroxylase is an enzyme of the steroid pathway that is involved in the biosynthesis of cortisol and aldosterone by hydroxylation of 17α-hydroxyprogesterone and progesterone at the C21 position. Mutations in CYP21A2, the gene encoding 21-hydroxylase, cause the most frequent form of the autosomal recessive disorder congenital adrenal hyperplasia (CAH). In this study, we generated a humanized 21-hydroxylase mouse model as the first step to the generation of mutant mice with different CAH-causing mutations. We replaced the mouse Cyp21a1 gene with the human CYP21A2 gene using homologous recombination in combination with CRISPR/Cas9 technique. The aim of this study was to characterize the new humanized mouse model. All results described are related to the homozygous animals in comparison with wild-type mice. We show analogous expression patterns of human 21-hydroxylase by the murine promoter and regulatory elements in comparison to murine 21-hydroxylase in wild-type animals. As expected, no Cyp21a1 transcript was detected in homozygous CYP21A2 adrenal glands. Alterations in adrenal gene expression were observed for Cyp11a1, Star, and Cyb11b1. These differences, however, were not pathological. Outward appearance, viability, growth, and fertility were not affected in the humanized CYP21A2 mice. Plasma steroid levels of corticosterone and aldosterone showed no pathological reduction. In addition, adrenal gland morphology and zonation were similar in both the humanized and the wild-type mice. In conclusion, humanized homozygous CYP21A2 mice developed normally and showed no differences in histological analyses, no reduction in adrenal and gonadal gene expression, or in plasma steroids in comparison with wild-type littermates.

Molecular Diagnosis of Steroid 21-Hydroxylase Deficiency: A Practical Approach

Adrenal insufficiency in paediatric patients is mostly due to congenital adrenal hyperplasia (CAH), a severe monogenic disease caused by steroid 21-hydroxylase deficiency (21-OHD, encoded by the CYP21A2 gene) in 95% of cases. CYP21A2 genotyping requires careful analyses that guaranty gene-specific PCR, accurate definition of pseudogene-gene chimeras, gene duplications and allele dropout avoidance. A small panel of well-established disease-causing alterations enables a high diagnostic yield in confirming/discarding the disorder not only in symptomatic patients but also in those asymptomatic with borderline/positive results of 17-hydroxyprogesterone. Unfortunately, the complexity of this locus makes it today reluctant to high throughput techniques of massive sequencing. The strong relationship existing between the molecular alterations and the degree of enzymatic deficiency has allowed genetic studies to demonstrate its usefulness in predicting/classifying the clinical form of the disease. Other aspects of interest regarding molecular studies include its independence of physiological variations and analytical interferences, its usefulness in the diagnosis of simple virilizing forms in males and its inherent contribution to the genetic counseling, an aspect of great importance taking into account the high carrier frequency of CAH in the general population. Genetic testing of CYP21A2 constitutes an irreplaceable tool to detect severe alleles not just in family members of classical forms but also in mild late-onset forms of the disease and couples. It is also helpful in areas such as assisted reproduction and preimplantation diagnosis. Molecular diagnosis of 21-OHD under expert knowledge definitely contributes to a better management of the disease in every step of the clinical course.

Congenital adrenal hyperplasia with homozygous and heterozygous mutations: a rare family case report

BACKGROUND

Congenital adrenal hyperplasia (CAH), characterized by defective adrenal steroidogenesis, is transmitted in an autosomal recessive manner. Mutations in the steroid 21-hydroxylase gene CYP21A2 causing steroid 21-hydroxylase deficiency account for most cases of CAH. The c.145l-1452delGGinsC gene mutation is rare, and only one case has been reported, but the form of gene mutation is different from this case, resulting in different clinical phenotype. The most common pathogenic genotype of CAH is a homozygous or compound heterozygous mutation, but CAH patients homozygous for the p.I173N mutation and heterozygous for the c.1451-1452delGGinsC mutation have not been reported previously. We report herein a familial case of CAH, in which both siblings carry the rare homozygous p.I173N mutation and heterozygous c.1451-1452delGGinsC mutation.

CASE PRESENTATION

The proband showed amenorrhea, infertility, polycystic ovaries, and increased levels of androgen, rather than the typical clinical manifestations of CAH such as an adrenal crisis or masculine vulva, so was misdiagnosed with polycystic ovary syndrome for many years. Following a correct diagnosis of CAH, she was given glucocorticoid treatment, her menstruation became more regular, and she became pregnant and delivered a healthy baby girl.

CONCLUSIONS

The genotypes may be p.I173N homozygous or p.I173N/c.1451-1452delGGinsC heterozygous, both mutations could be pathogenic. This complex combination of mutations has not been reported or studied before. Through the report and analysis of this genotype, the content of CAH gene bank is enriched and the misdiagnosis rate of CAH is reduced.

Congenital Adrenal Hyperplasia-Current Insights in Pathophysiology, Diagnostics, and Management

Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders affecting cortisol biosynthesis. Reduced activity of an enzyme required for cortisol production leads to chronic overstimulation of the adrenal cortex and accumulation of precursors proximal to the blocked enzymatic step. The most common form of CAH is caused by steroid 21-hydroxylase deficiency due to mutations in CYP21A2. Since the last publication summarizing CAH in Endocrine Reviews in 2000, there have been numerous new developments. These include more detailed understanding of steroidogenic pathways, refinements in neonatal screening, improved diagnostic measurements utilizing chromatography and mass spectrometry coupled with steroid profiling, and improved genotyping methods. Clinical trials of alternative medications and modes of delivery have been recently completed or are under way. Genetic and cell-based treatments are being explored. A large body of data concerning long-term outcomes in patients affected by CAH, including psychosexual well-being, has been enhanced by the establishment of disease registries. This review provides the reader with current insights in CAH with special attention to these new developments.

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.

Innate immune genes of the chicken MHC and related regions

Compared to the major histocompatibility complex (MHC) of typical mammals, the chicken BF/BL region is small and simple, with most of the genes playing central roles in the adaptive immune response. However, some genes of the chicken MHC are almost certainly involved in innate immunity, such as the complement component C4 and the lectin-like receptor/ligand gene pair BNK and Blec. The poorly expressed classical class I molecule BF1 is known to be recognised by natural killer (NK) cells and, analogous to mammalian immune responses, the classical class I molecules BF1 and BF2, the CD1 homologs and the butyrophilin homologs called BG may be recognised by adaptive immune lymphocytes with semi-invariant receptors in a so-called adaptate manner. Moreover, the TRIM and BG regions next to the chicken MHC, along with the genetically unlinked Y and olfactory/scavenger receptor regions on the same chromosome, have multigene families almost certainly involved in innate and adaptate responses. On this chicken microchromosome, the simplicity of the adaptive immune gene systems contrasts with the complexity of the gene systems potentially involved in innate immunity.

Genotype-Structure-Phenotype Correlations of Disease-Associated IGF1R Variants and Similarities to Those of INSR Variants

We previously reported genotype-phenotype correlations in 12 missense variants causing severe insulin resistance, located in the second and third fibronectin type III (FnIII) domains of the insulin receptor (INSR), containing the α-β cleavage and part of insulin-binding sites. This study aimed to identify genotype-phenotype correlations in FnIII domain variants of IGF1R, a structurally related homolog of INSR, which may be associated with growth retardation, using the recently reported crystal structures of IGF1R. A structural bioinformatics analysis of five previously reported disease-associated heterozygous missense variants and a likely benign variant in the FnIII domains of IGF1R predicted that the disease-associated variants would severely impair the hydrophobic core formation and stability of the FnIII domains or affect the α-β cleavage site, while the likely benign variant would not affect the folding of the domains. A functional analysis of these variants in CHO cells showed impaired receptor processing and autophosphorylation in cells expressing the disease-associated variants but not in those expressing the wild-type form or the likely benign variant. These results demonstrated genotype-phenotype correlations in the FnIII domain variants of IGF1R, which are presumably consistent with those of INSR and would help in the early diagnosis of patients with disease-associated IGF1R variants.

Comprehensive Genetic Testing of CYP21A2: A Retrospective Analysis in Patients with Suspected Congenital Adrenal Hyperplasia

The most common form of congenital adrenal hyperplasia (CAH) results from a deficiency of the 21-hydroxylase enzyme (21-OHD), presenting with a broad spectrum of clinical phenotypes according to the CYP21A2 gene mutations. Of the 59 patients with suspected CAH, 62.7% presented a positive genetic result. Of them, 78.4% and 18.9% presented with non-classical and classical forms, respectively. An overall phenotype-genotype correlation of 88.9% was observed. Biochemically, 17-hydroxiprogesterone concentrations were significantly higher in genetically confirmed patients. Genetically, 36 patients presented with previously reported pathogenic variants, and one presented a new variant in homozygosis. Among the 74 alleles tested, point mutations were found in 89.2% and large rearrangements were found in the rest. The most prevalent pathogenic variant was p.(Val282Leu). The inclusion of relatives revealed one further case. Interestingly, 87.5% of relatives were carriers of a pathogenic variant, including two siblings initially classified as genetically positive. In addition, the study of male partners with gestational desire identified several carriers of mild mutations. Studying the allelic distribution of the variants also allowed for reclassifying one patient. In conclusion, a genetic approach including Sanger sequencing, multiplex ligation-dependent probe amplification (MLPA) analysis, and allelic distribution of the pathogenic variants represents a beneficial tool for better classifying patients with 21-OHD.

A Case of Salt-Wasting Congenital Adrenal Hyperplasia with Triple Homozygous Mutation: Review of Literature

Congenital adrenal hyperplasia (CAH) due to steroid 21-hydroxylase deficiency represents a group of autosomal recessive disorders characterized by impaired cortisol production due to altered upstream steroid conversions, subclassified as classic and nonclassic forms. The genotype-phenotype correlation is possible in the most frequent case but not in all. Despite in literature many mutations are known, there is the possibility of finding a new genetic pattern in patients with CAH.

Clinical outcomes and characteristics of P30L mutations in congenital adrenal hyperplasia due to 21-hydroxylase deficiency

Despite numerous studies in the field of congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency, some clinical variability of the presentation and discrepancies in the genotype/phenotype correlation are still unexplained. Some, but not all, discordant phenotypes caused by mutations with known enzyme activity have been explained by in silico structural changes in the 21-hydroxylase protein. The incidence of P30L mutation varies in different populations and is most frequently found in several Central and Southeast European countries as well as Mexico. Patients carrying P30L mutation present predominantly as non-classical CAH; however, simple virilizing forms are found in up to 50% of patients. Taking into consideration the residual 21-hydroxulase activity present with P30L mutation this is unexpected. Different mechanisms for increased androgenization in patients carrying P30L mutation have been proposed including influence of different residues, accompanying promotor allele variability or mutations, and individual androgene sensitivity. Early diagnosis of patients who would present with SV is important in order to improve outcome. Outcome studies of CAH have confirmed the uniqueness of this mutation such as difficulties in phenotype classification, different fertility, growth, and psychologic issues in comparison with other genotypes. Additional studies of P30L mutation are warranted.

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.

Detection of a novel severe mutation affecting the CYP21A2 gene in a Chilean male with salt wasting congenital adrenal hyperplasia

PURPOSE

21-hydroxylase deficiency (21-OHD) is a congenital adrenal disease with more than 200 mutations published to date. The aim of this report is to describe a severe novel mutation of the CYP21A2 gene.

METHOD

We describe a case of a 39-year-old male diagnosed with a salt wasting congenital adrenal hyperplasia (SWCAH) due to 21-OHD. The genetic testing was done using a combination of three methods (PCR XL, SALSA-MLPA, and bidirectional sequencing) and finally an in silico analysis.

RESULTS

The genetic testing demonstrated three severe mutations of the CYP21A2 gene (p.Gln318*; c.290-13C>G; and p.Trp86*), being the last one a novel mutation not previously reported. The in silico modeling of the p.Trp86* (c.258G>A) showed a truncated CYP21A2 protein that loses all the main structural features required for activity, such as the HEM binding domain and the hormone binding site.

CONCLUSION

We present an adult man with an SWCAH due to 21-OHD who carried three severe mutations of the CYP21A2 gene, one of them, p.Trp86* (c.258G>A) has not been previously described.

p.Gln318X and p.Val281Leu as the Major Variants of CYP21A2 Gene in Children with Idiopathic Premature Pubarche

Premature pubarche (PP) is the appearance of sexual hair in children before puberty. The PP phenotype may attribute to nonclassic congenital adrenal hyperplasia (NC-CAH). In this study, we investigated the role of CYP21A2 gene variants in patients with PP in the Iranian population. Forty patients (13 males and 27 females), clinically diagnosed with PP, were analyzed for molecular testing of CYP21A2 gene variants. Direct sequencing was performed for the samples. Also, gene dosage analysis was performed for the cases. Fourteen patients (35%) had a mutation of p.Gln318X and p.Val281Leu, out of which 10% had regulatory variants. Approximately 10% of the patients were homozygous (NC-CAH). 78.5% (11/14) of patients had trimodular RCCX of which 5 patients had two copies of CYP21A1P pseudogene. The prevalence of p.Val281Leu was higher than p.Gln318X in PP patients. In conclusion, CYP21A2 variant detection has implications in the genetic diagnosis of PP phenotype. The genetic characterization of the CYP21A2 gene is important for characterizing the variable phenotype of carriers and genetic counseling of PP and NC-CAH patients.

How do mutations affect the structural characteristics and substrate binding of CYP21A2? An investigation by molecular dynamics simulations

CYP21A2 mutations affect the activity of the protein leading to CAH disease.

Biosynthetic approach to combine the first steps of cardenolide formation in Saccharomyces cerevisiae

A yeast expression plasmid was constructed containing a cardenolide biosynthetic module, referred to as CARD II, using the AssemblX toolkit, which enables the assembly of large DNA constructs. The genes cloned into the vector were (a) a Δ⁵‐3β‐hydroxysteroid dehydrogenase gene from Digitalis lanata, (b) a steroid Δ⁵‐isomerase gene from Comamonas testosteronii, (c) a mutated steroid‐5β‐reductase gene from Arabidopsis thaliana, and (d) a steroid 21‐hydroxylase gene from Mus musculus. A second plasmid bearing an ADR/ADX fusion gene from Bos taurus was also constructed. A Saccharomyces cerevisiae strain bearing these two plasmids was generated. This strain, termed “CARD II yeast”, was capable of producing 5β‐pregnane‐3β,21‐diol‐20‐one, a central intermediate in 5β‐cardenolide biosynthesis, starting from pregnenolone which was added to the culture medium. Using this approach, five consecutive steps in cardenolide biosynthesis were realized in baker's yeast.

Human cytochrome P450 enzymes 5-51 as targets of drugs and natural and environmental compounds: mechanisms, induction, and inhibition - toxic effects and benefits

Cytochrome P450 (P450, CYP) enzymes have long been of interest due to their roles in the metabolism of drugs, pesticides, pro-carcinogens, and other xenobiotic chemicals. They have also been of interest due to their very critical roles in the biosynthesis and metabolism of steroids, vitamins, and certain eicosanoids. This review covers the 22 (of the total of 57) human P450s in Families 5-51 and their substrate selectivity. Furthermore, included is information and references regarding inducibility, inhibition, and (in some cases) stimulation by chemicals. We update and discuss important aspects of each of these 22 P450s and questions that remain open.

Measuring the structural impact of mutations on cytochrome P450 21A2, the major steroid 21-hydroxylase related to congenital adrenal hyperplasia

Congenital adrenal hyperplasia is an inherited autosomal recessive disorder related to deficient cortisol synthesis. The deficiency of steroid 21-hydroxylase (cytochrome P450 21A2), an enzyme involved in cortisol synthesis, is responsible for ∼95% of cases of congenital adrenal hyperplasia. This metabolic disease exhibits three clinical forms: salt-wasting, simple virilizing, and non-classical form, which are divided according to the degree of severity. In the present study, structural and mutational analyses were performed in order to identify the structural impact of mutations on cytochrome P450 21A2 and correlate them with patient clinical severity. The following mutations were selected: arginine-356 to tryptophan (R356W), proline-30 to leucine (P30L), isoleucine-172 to asparagine (I172N), valine-281 to leucine (V281L), and the null mutation glutamine-318 (Q318X). Our computational approach mapped the location of residues on P450 and identified their implications on enzyme electrostatic potential mapping to progesterone and heme binding pockets. Using molecular dynamics simulations, we analyzed the structural stability of ligand binding and protein structure, as well as possible conformational changes at the catalytic pocket that leads to impairment of enzymatic activity. Our study sheds light on the impact structural mutations have over steroid 21-hydroxylase structure-function in the cell.Communicated by Ramaswamy H. Sarma.

Prenatal genetic testing and treatment for congenital adrenal hyperplasia

Couples at risk for autosomal recessive congenital adrenal hyperplasia often request anticipatory guidance and genetic counseling. Initially, hormones in amniotic fluid were measured to distinguish affected female fetuses from unaffected fetuses. With the molecular era, more-targeted approaches became possible. Prenatal genetic diagnosis via amniocentesis or chorionic villus sampling was used to determine the need for continuing fetal therapy (dexamethasone), allowing cessation if the fetus was unaffected. Newer methods now allow diagnosis earlier in gestation, further shortening the treatment time for unaffected female fetuses who will not develop genital ambiguity. Preimplantation genetic testing permits transfer only of an unaffected female or male fetus. Analysis of maternal cell-free DNA based on quantitative differences in the amount of allele parental DNA permits affected pregnancies to be differentiated from unaffected pregnancies.

Genetics of congenital adrenal hyperplasia and genotype-phenotype correlation

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is caused by mutations in the CYP21A2 gene, located on the short arm of chromosome 6. The two main underlying mechanisms of CYP21A2 defects are large gene deletion and conversion. Anticipation of the phenotypes associated with different combinations of CYP21A2 mutations remains the most important determinant in prenatal diagnosis and counseling of the expectant couple who are determined to be at risk for congenital adrenal hyperplasia.

Novel variants of CYP21A2 in Vietnamese patients with congenital adrenal hyperplasia

BACKGROUND

Congenital adrenal hyperplasia (CAH) (OMIM #201910) is a complex disease most often caused by pathogenic variant of the CYP21A2 gene. We have designed an efficient multistep approach to diagnose and classify CAH cases due to CYP21A2 variant and to study the genotype-phenotype relationship.

METHODS

A large cohort of 212 Vietnamese patients from 204 families was recruited. We utilized Multiplex Ligation-dependent Probe Amplification to identify large deletion or rearrangement followed by complete gene sequencing of CYP21A2 to map single-nucleotide changes and possible novel variants.

RESULTS

Pathogenic variants were identified in 398 out of 408 alleles (97.5%). The variants indexed span across most of the CYP21A2 gene regions. The most common genotypes were: I2g/I2g (15.35%); Del/Del (14.4%); Del/I2g (10.89%); p.R356W/p.R356W (6.44%); and exon 1-3 del/exon 1-3 del (5.44%). In addition to the previously characterized and documented variants, we also discovered six novel variants which were not previously reported, in silico tools were used to support the pathogenicity of these variants.

CONCLUSION

The result will contribute in further understanding the genotype-phenotype relationship of CAH patients and to guide better treatment and management of the affected.

Compound heterozygosity for a whole gene deletion and p.R124C mutation in CYP21A2 causing nonclassic congenital adrenal hyperplasia

We present a family with 2 members who received long-term steroid treatment for presumed classic congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency, until molecular testing revealed nonclassic CAH, not necessarily requiring treatment. A 17-year-old male presented to our clinic on glucocorticoid and mineralocorticoid treatment for classic CAH. He was diagnosed at 4 years of age based on mild-moderate elevations of 17-hydroxyprogesterone (17-OHP) and adrenocorticotropic hormone (ACTH), but without evidence of precocious adrenarche/puberty. Due to his diagnosis, his clinically asymptomatic 3-year-old sister was tested and also found to have elevated ACTH and 17-OHP levels and was started on glucocorticoids for classic CAH. Family history revealed a healthy sibling who had no biochemical evidence of CAH and consanguineous healthy parents. We questioned the diagnosis of classic CAH and performed an ACTH1-24 stimulation test, which showed a level of 17-OHP in the borderline range between classic and nonclassic CAH. Molecular testing, using sequencing and multiplex ligation-dependent probe amplification analysis of CYP21A2, revealed that both affected siblings were compound heterozygotes for a whole-gene deletion and a, likely pathogenic (nonclassical), sequence variant, p.R124C. The asymptomatic father had the same genotype, while the mother showed one deleted copy and 2 active copies, making her an asymptomatic carrier. Our report demonstrates the importance of molecular testing in atypical cases of CAH, as well as the importance of both sequencing and deletion analysis. The results of molecular testing should be interpreted in clinical context, and treatment should be prescribed according to guidelines when available.

Clinical presentation and mutational spectrum in a series of 166 patients with classical 21-hydroxylase deficiency from South China

Classical 21-hydroxylase deficiency (21-OHD) due to mutations in the cytochrome P450 family 21 subfamily A member 2 (CYP21A2) gene is the most common type of congenital adrenal hyperplasia (CAH). In this study, we analyzed clinical and molecular data of 166 patients with classical CAH in South China. Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA) method were used to detect mutations in these 99 salt wasting (SW) patients and 67 simple virilizing (SV) patients. Micro-conversion mutation IVS2-13A/C > G (I2G) was the most frequent mutation in both SW form (42.9%) and SV form (41.8%) in our large cohort, and large gene deletion or large gene conversion also commonly resulted in classical CAH. Rare mutations only account for 8.4% of all alleles, among them four novel variants p.S126X, p.C429X, c.1209_1210insT and c.840delG were responsible for the clinical presentations. CYP21A2 gene duplications linked to the mutation Q319X were found in our cohort, though these cases were rather rare. In this study, we provided detailed clinical data and mutation spectrum to confirm the common mutations in Chinese populations, especially in South China,which will contribute to further genetic consultation and prenatal diagnosis. Sanger sequencing combined with MLPA method could detect most mutation types in the CYP21A2 gene effectively.

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.

Functional characterization and molecular modeling of the mutations in CYP21A2 gene from patients with Congenital Adrenal Hyperplasia

Steroid 21-Hydroxylase deficiency is an inherited autosomal recessive metabolic disorder of the adrenal steroidogenesis caused due to mutations in the CYP21A2 gene in 95% of CAH cases. Notably, the de novo mutations arise at the rate of 3-5%, therefore the functional characterization is of utmost importance for categorization of the novel mutations. Herein, we have functionally characterized the CYP21A2 missense mutations viz., p. F306V and p. H365N. Notably, both the mutations were harbored by the patients exhibiting the non classical phenotype. We followed the approach of in vitro characterization of the mutant proteins expressed in COS7 cells. Of note, all the mutant constructs exhibited reduced residual enzyme activity fraternized with altered kinetic constants accompanied by higher requirement for the activation energy. Further, there was reduced protein expression in the mutant constructs to that of the wild-type. Molecular modeling suggested alteration in the structure-function relationship of the protein due to mutations. The evidence suggested by the in vitro and the in silico characterization of mutations directed us to conclude that both, p. F306V and p. H365N should be considered as non classical CAH causing mutations. Conceivably, the knowledge about the functional consequences of the mutations is the basis for improved genetic counseling with respect to prognosis and therapeutic implications.

Genotype Is Associated to the Degree of Virilization in Patients With Classic Congenital Adrenal Hyperplasia

Background: Molecular defects of CYP21A2 consistently decrease 21-hydroxylase activity and result in a variable expression of disease severity in patients with congenital adrenal hyperplasia (CAH). Aim: The genotype and biochemical findings were examined in an attempt to reveal any association to the degree of virilization in classic CAH patients. Methods: The study included 18 CAH patients with complete characterization of CYP21A2 mutations and were sorted based on the severity of the inherited mutations and the expected percentage of 21-hydroxylase enzyme activity. Results: Eleven out of the 18 patients manifested the SW form with the remaining seven exhibiting the SV form. The most frequent genetic defect in the classic salt-wasting (SW) and simple virilising (SV) forms was the IVS2-13A/C>G (36.1%) mutation, followed by delEX1-3 (19.4%) and p.Ile172Asn (19.4%). Four patients, who shared a combination of two mutations belonging to the most severe type, manifested only the SW form. Four out of five patients who shared homozygosity in the IVS2-13A/C>G mutation, demonstrated the SW form and only one demonstrated the SV form. All four patients who shared the p.Ile172Asn mutation, either in the homozygous or compound heterozygous state, manifested the SV form. Interestingly, a female neonate with SW, bearing the IVS2-13A/C>G/Large del, exhibited complete male virilisation (Prader 5). The remaining four affected female new-borns also exhibited the SW form, with two of them virilised as Prader 3 and the other two as Prader 4. Virilisation with clitoromegaly was also observed in one female, who presented premature adrenarche and carried the least severe p.Pro30Leu mutation. Conclusion: The frequency of the underlying mutations in our patients, with the classic form of CAH, varies but were quite similar to the ones reported in the Mediterranean region. Therefore, the identification of severe CYP21A2 defects in Cypriot patients and their comparison with the incidence and severity in different populations, will create a valuable diagnostic tool for genetic counseling in the classic form of CAH.

CYP21A2 genetic profile in 14 Egyptian children with suspected congenital adrenal hyperplasia: a diagnostic challenge

CYP21A2 genotyping remains an important element in the diagnosis and management of congenital adrenal hyperplasia, and establishing accurate genotype-phenotype correlations has facillitated adequate genetic counseling and prenatal management for at-risk families. Despite extensive efforts to establish a clear genotype-phenotype correlation, some discordance remains. Establishing a diagnosis of congenital adrenal hyperplasia on the basis of biochemical and clinical data is occasionally challenging, and the identification of CYP21A2 mutations may help confirm the diagnosis. We review the diagnostic challenges despite an extensive genetic evaluation for 14 patients with a suspected clinical and biochemical diagnosis of congenital adrenal hyperplasia. Other diagnostic entities should be considered in the absence of convincing genetic data.

Clinical, genetic, and structural basis of apparent mineralocorticoid excess due to 11β-hydroxysteroid dehydrogenase type 2 deficiency

Mutations in 11β-hydroxysteroid dehydrogenase type 2 gene (HSD11B2) cause an extraordinarily rare autosomal recessive disorder, apparent mineralocorticoid excess (AME). AME is a form of low renin hypertension that is potentially fatal if untreated. Mutations in the HSD11B2 gene result either in severe AME or a milder phenotype (type 2 AME). To date, ∼40 causative mutations have been identified. As part of the International Consortium for Rare Steroid Disorders, we have diagnosed and followed the largest single worldwide cohort of 36 AME patients. Here, we present the genotype and clinical phenotype of these patients, prominently from consanguineous marriages in the Middle East, who display profound hypertension and hypokalemic alkalosis. To correlate mutations with phenotypic severity, we constructed a computational model of the HSD11B2 protein. Having used a similar strategy for the in silico evaluation of 150 mutations of CYP21A2, the disease-causing gene in congenital adrenal hyperplasia, we now provide a full structural explanation for the clinical severity of AME resulting from each known HSD11B2 missense mutation. We find that mutations that allow the formation of an inactive dimer, alter substrate/coenzyme binding, or impair structural stability of HSD11B2 yield severe AME. In contrast, mutations that cause an indirect disruption of substrate binding or mildly alter intramolecular interactions result in type 2 AME. A simple in silico evaluation of novel missense mutations could help predict the often-diverse phenotypes of an extremely rare monogenic disorder.

Nouveautés dans l’hyperplasie congénitale des surrénales

Congenital adrenal hyperplasia is an autosomal recessive disease due to functional abnormalities of adrenal steroid enzymes. The most common form of the disease is due to a 21-hydroxylase deficiency. The classical forms (most severe) are characterized by a deficiency in cortisol and sometimes in aldosterone, which may compromise the vital prognosis of neonates, and by an increase in androgen synthesis, leading to the virilization of girls' external genitalia at birth, followed by clinical signs of hyperandrogenism during childhood and adolescence. Neonatal screening has improved management and reduced morbidity and mortality in the neonatal period, but its performance could be broadly optimised by adjusting the assay techniques or the biomarkers used. The genetic diagnosis is difficult owing to the large genetic heterogeneity of the 6p21.3 region, which contains the CYP21A2 gene, especially with respect to the use of new-generation techniques of sequencing. Prenatal diagnosis is now possible as early as 6 weeks of gestation, but prenatal treatment remains controversial, awaiting results from prospective cohorts evaluating its long-term impact. Since conventional therapies have limitations, new therapies are currently being developed to allow better control of androgen synthesis and a substitutive treatment that respects the physiological rhythm of cortisol secretion, which would limit the development of long-term complications.

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.

Structural Basis and Genotype-Phenotype Correlations of INSR Mutations Causing Severe Insulin Resistance

The insulin receptor (INSR) gene was analyzed in four patients with severe insulin resistance, revealing five novel mutations and a deletion that removed exon 2. A patient with Donohue syndrome (DS) had a novel p.V657F mutation in the second fibronectin type III domain (FnIII-2), which contains the α-β cleavage site and part of the insulin-binding site. The mutant INSR was expressed in Chinese hamster ovary cells, revealing that it reduced insulin proreceptor processing and impaired activation of downstream signaling cascades. Using online databases, we analyzed 82 INSR missense mutations and demonstrated that mutations causing DS were more frequently located in the FnIII domains than those causing the milder type A insulin resistance (P = 0.016). In silico structural analysis revealed that missense mutations predicted to severely impair hydrophobic core formation and stability of the FnIII domains all caused DS, whereas those predicted to produce localized destabilization and to not affect folding of the FnIII domains all caused the less severe Rabson-Mendenhall syndrome. These results suggest the importance of the FnIII domains, provide insight into the molecular mechanism of severe insulin resistance, will aid early diagnosis, and will provide potential novel targets for treating extreme insulin resistance.

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.

Clinical, genetic, and structural basis of congenital adrenal hyperplasia due to 11β-hydroxylase deficiency

Congenital adrenal hyperplasia (CAH), resulting from mutations in CYP11B1, a gene encoding 11β-hydroxylase, represents a rare autosomal recessive Mendelian disorder of aberrant sex steroid production. Unlike CAH caused by 21-hydroxylase deficiency, the disease is far more common in the Middle East and North Africa, where consanguinity is common often resulting in identical mutations. Clinically, affected female newborns are profoundly virilized (Prader score of 4/5), and both genders display significantly advanced bone ages and are oftentimes hypertensive. We find that 11-deoxycortisol, not frequently measured, is the most robust biochemical marker for diagnosing 11β-hydroxylase deficiency. Finally, computational modeling of 25 missense mutations of CYP11B1 revealed that specific modifications in the heme-binding (R374W and R448C) or substrate-binding (W116C) site of 11β-hydroxylase, or alterations in its stability (L299P and G267S), may predict severe disease. Thus, we report clinical, genetic, hormonal, and structural effects of CYP11B1 gene mutations in the largest international cohort of 108 patients with steroid 11β-hydroxylase deficiency CAH.