Molecular genetic analysis of nonclassic steroid 21-hydroxylase deficiency associated with HLA-B14,DR1

A MinION-based Long-Read Sequencing Application With One-Step PCR for the Genetic Diagnosis of 21-Hydroxylase Deficiency

CONTEXT

Recently developed long-read sequencing (LRS) technology has been considered an option for CYP21A2 analysis. However, the clinical use of LRS for CYP21A2 analysis is limited.

OBJECTIVE

This study's objective is to develop an efficient and low-cost LRS system for CYP21A2 screening.

METHODS

A DNA fragment library was prepared in a single polymerase chain reaction (PCR) that covers the entire CYP21A2 gene and all known junctions caused by TNXB gene structural rearrangements, yielding a single 8-kb product of CYP21A2 or CYP21A1P/CYP21A2 chimera. After barcoding, the PCR products were sequenced on a MinION-based platform with Flongle Flow Cell R9.4.1 and R10.4.1.

RESULTS

The reference genotypes of 55 patients with 21-hydroxylase deficiency (21OHD) were established using the conventional method with multiplex ligation-dependent probe amplification (MLPA) and nested PCR. LRS using Flongle Flow Cell R9.4.1 yielded consistent results. Additionally, the recently updated LRS "duplex" analysis with Flongle flow cell R10.4.1 was tested to reveal an advantage of accurately sequencing a variant located on the homopolymer region. By introducing a barcode system, the cost was reduced to be comparable to that of conventional analysis. A novel single-nucleotide variation was discovered at the acceptor site of intron 7, c.940-1G > C. We also identified a subtype of the classical chimeric junction CH2, "CH2a," in the region from the latter part of intron 5 to exon 6.

CONCLUSION

We successfully established a novel low-cost and highly accurate LRS system for 21OHD genetic analysis. Our study provides insight into the feasibility of LRS for diagnosing 21OHD and other genetic diseases caused by structural rearrangements.

History of Adrenal Research: From Ancient Anatomy to Contemporary Molecular Biology

The adrenal is a small, anatomically unimposing structure that escaped scientific notice until 1564 and whose existence was doubted by many until the 18th century. Adrenal functions were inferred from the adrenal insufficiency syndrome described by Addison and from the obesity and virilization that accompanied many adrenal malignancies, but early physiologists sometimes confused the roles of the cortex and medulla. Medullary epinephrine was the first hormone to be isolated (in 1901), and numerous cortical steroids were isolated between 1930 and 1949. The treatment of arthritis, Addison's disease, and congenital adrenal hyperplasia (CAH) with cortisone in the 1950s revolutionized clinical endocrinology and steroid research. Cases of CAH had been reported in the 19th century, but a defect in 21-hydroxylation in CAH was not identified until 1957. Other forms of CAH, including deficiencies of 3β-hydroxysteroid dehydrogenase, 11β-hydroxylase, and 17α-hydroxylase were defined hormonally in the 1960s. Cytochrome P450 enzymes were described in 1962-1964, and steroid 21-hydroxylation was the first biosynthetic activity associated with a P450. Understanding of the genetic and biochemical bases of these disorders advanced rapidly from 1984 to 2004. The cloning of genes for steroidogenic enzymes and related factors revealed many mutations causing known diseases and facilitated the discovery of new disorders. Genetics and cell biology have replaced steroid chemistry as the key disciplines for understanding and teaching steroidogenesis and its disorders.

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.

Assessing the risk of having a child with classic 21-hydroxylase deficiency: a new paradigm

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is a complicated condition genetically, clinically, and treatment wise. Genetically, there are numerus mutations with different effect on enzyme activity that make genetic diagnosis a challenge. Clinically, there are a wide range of presentations from asymptomatic patients to the severe life-threatening classic CAH. Both an asymptomatic heterozygote and a mildly affected non-classical patient can carry a 'severe' mutation and endow it to their offspring. We present a case of non-classic CAH and discuss the problematic relations between biochemical and genetic diagnosis. By integrating the seemingly contradicting literature, we provide a new simple tool to assess the risk of such patients to give birth to a child with classic CAH.

Non-Classical 21-Hydroxylase Deficiency: Analysis of a Mutant Gene in a Uyghur Family and Literature Review

OBJECTIVE

The gene mutation and clinical characteristics of a patient with non-classical 21-hydroxylase deficiency and his family were analyzed.

METHODS

A patient was diagnosed with non-classical 21-hydroxylase deficiency in the Department of Endocrinology of People's Hospital of Xinjiang Uygur Autonomous Region in December 2016. The clinical data and related gene-sequencing results were analyzed. The detected mutations were verified in nine members of the family.

RESULTS

Gene-sequencing results revealed that the proband and the other three members of the family (proband, proband's mother's younger brother and the proband's mother's younger brother's younger daughter, and proband's second elder sister) shared the following mutations: Ile173Asn, Ile237Asn, Val238Glu, Met240Lys, Val282Leu, Leu308Phefs*6, Gln319Ter, Arg357Trp, and Arg484Profs. The Val282Leu mutation was heterozygous in the proband's mother's younger brother's younger daughter, but homozygous in the other three individuals. The father of the proband, the elder brother of the father of the proband, the third younger brother of the father of the proband, and the elder sister of the proband all carried only the Val282Leu mutation.

CONCLUSION

Val282Leu is the gene responsible for non-classical 21-hydroxylase deficiency. Screening for this gene in the offspring of patients with non-classical 21-hydroxylase deficiency may help to identify cases early.

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.

Therapeutic challenges in a patient with the simple virilizing (SV) form of congenital adrenal hyperplasia (CAH) due to the P30L/I172N genotype

Background Steroid 21-hydroxylase deficiency is an autosomal recessive disorder, present in 90-95% of all cases with congenital adrenal hyperplasia (CAH). The classical simple virilizing (SV) form of the disease causes virilization of the external genitalia in newborn females and pseudo-precocious puberty in both sexes, due to reactive androgen overproduction. Case presentation We describe a 3.5-year-old girl presenting with pubarche, P2 according to Tanner, advanced bone age of 6 years and 10 months, and high serum levels of 17-hydroxyprogesterone (17-OHP). Molecular analysis of the nine most common pseudogene-derived CYP21A2 point mutations was performed in the patient and her family members using the polymerase chain reaction/amplification-created restriction site (PCR/ACRS) method. We detected the P30L/I172N genotype in the patient. She had inherited a mild P30L mutation from her mother and a severe I172N mutation from her father. Conclusions Although the CAH phenotype is determined by the allele that produces most of the enzyme activity and the mild non-classical (NC) phenotype should be expected, the mild P30L known to be more virilizing probably induced the classical SV phenotype in our patient. A continuous regimen of hydrocortisone at a recommended dose failed to decrease the 17-OHP sufficiently. Careful tapering of the dose did not help, and her pubic hair advanced to P3 according to Tanner. Individually tailored treatment is warranted in this patient.

The Complexities in Genotyping of Congenital Adrenal Hyperplasia: 21-Hydroxylase Deficiency

The deficiency of 21-hydroxylase due to CYP21A2 pathogenic variants is a rather frequent disease with serious consequences, going from a real mortality risk to infertility and to milder symptoms, nevertheless important for affecting the patients' self-esteem. In the most severe cases life-threatening adrenal salt wasting crises may occur. Significant morbidity including the possibility of mistaken gender determination, precocious puberty, infertility and growth arrest with consequent short stature may also affect these patients. In the less severe cases milder symptoms like hirsutism will likely affect the image of the self with strong psychological consequences. Its diagnosis is confirmed by 17OH-progesterone dosages exceeding the cut-off value of 10/15 ng/ml but genotyping is progressively assuming an essential role in the study of these patients particularly in confirming difficult cases, determining some aspects of the prognosis and allowing a correct genetic counseling. Genotyping is a difficult process due to the occurrence of both a gene and a highly homologous pseudo gene. However, new tools are opening new possibilities to this analysis and improving the chances of a correct diagnosis and better understanding of the underlying mechanisms of the disease. Beyond the 10 classic pathogenic variants usually searched for in most laboratories, a correct analysis of 21OH-deficiency cases implies completely sequencing of the entire gene and the determination of gene duplications. These are now recognized to occur frequently and can be responsible for some false positive cases. And finally, because gene conversions can include several pathogenic variants one cannot be certain of identifying that both alleles are affected without studying parental DNA samples. A complete genotype characterization should be considered essential in the preparation for pregnancy, even in the case of parents with milder forms of the disease, or even just carriers, since it has been reported that giving birth to progeny with the severe classic forms occurs with a much higher frequency than expected.

Intrafamilial Phenotypic Variability and Consequences of Non-Compliance with Treatment in Congenital Adrenal Hyperplasia and Congenital Hypothyroidism within a Single Family

BACKGROUND

Coexistence of congenital adrenal hyperplasia (CAH) and congenital hypothyroidism (CH) due to TG mutation in the same non-consanguineous family is rare.

CASE SERIES

We report 4 siblings born to unrelated parents, the father being an asymptomatic carrier of homozygous p.V281L and heterozygous p.I172N CYP21A2 mutations. Sibling 1 had salt-wasting CAH (CYP21A2 genotype Intron 2 splice/p.I172N and p.V281L). She also had CH (TG genotype p.R296/ p.T1416Rfs*30) and learning difficulties. Poor compliance and morbid obesity resulted in short stature, precocious puberty, hirsutism, amenorrhoea, insulin insensitivity and a possible adrenal adenoma. Sibling 3 (CYP21A2 and TG genotype similar to sibling 1) is a boy presenting with salt-wasting CAH, CH, and developmental delay. He was overweight and underwent precocious puberty. Although siblings 2 and 4 (both females) share the same CYP21A2 genotype (Intron 2 splice/p.V281L), the former only had biochemical evidence of CAH, while the latter presented at 9.8 years of age with a history of pubarche at 7 years and advanced bone age.

CONCLUSIONS

We report the unusual occurrence of 2 rare autosomal recessive diseases, CAH and CH. Our cases highlight the phenotypic variability of CAH and CH due to TG mutations, even within a single family, and illustrate the importance of optimal disease control.
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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.

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.

The Presence of Clitoromegaly in the Nonclassical Form of 21-Hydroxylase Deficiency Could Be Partially Modulated by the CAG Polymorphic Tract of the Androgen Receptor Gene

Background

In the nonclassical form (NC), good correlation has been observed between genotypes and 17OH-progesterone (17-OHP) levels. However, this correlation was not identified with regard to the severity of hyperandrogenic manifestations, which could depend on interindividual variability in peripheral androgen sensitivity. Androgen action is modulated by the polymorphic CAG tract (nCAG) of the androgen receptor (AR) gene and by polymorphisms in 5α-reductase type 2 (SRD5A2) enzyme, both of which are involved in the severity of hyperandrogenic disorders.

Objectives

To analyze whether nCAG-AR and SRD5A2 polymorphisms influence the severity of the nonclassical phenotype.

Patients

NC patients (n = 114) diagnosed by stimulated-17OHP ≥10 ng/mL were divided into groups according to the beginning of hyperandrogenic manifestations (pediatric and adolescent/adult) and CYP21A2 genotypes (C/C: homozygosis for mild mutations; A/C: compound heterozygosis for severe/mild mutations).

Methods

CYP21A2 mutations were screened by allelic-specific PCR, MLPA and/or sequencing. HpaII-digested and HpaII-undigested DNA samples underwent GeneScan analysis to study nCAG, and the SRD5A2 polymorphisms were screened by RLFP.

Results

Mean nCAG did not differ among pediatric, adolescent/adult and asymptomatic subjects. In the C/C genotype, we observed a significantly lower frequency of longer CAG alleles in pediatric patients than in adolescent/adults (p = 0.01). In patients carrying the A/C genotype, the frequencies of shorter and longer CAG alleles did not differ between pediatric patients and adolescent/adults (p>0.05). Patients with clitoromegaly had significantly lower weighted CAG biallelic mean than those without it: 19.1±2.7 and 21.6±2.5, respectively (p = 0.007), independent of the CYP21A2 genotype's severity. The SRD5A2 polymorphisms were not associated with the variability of hyperandrogenic NC phenotypes.

Conclusions

In this series, we observed a modulatory effect of the CAG-AR tract on clinical manifestations of the NC form. Although the NC form is a monogenic disorder, our preliminary data suggested that the interindividual variability of the hyperandrogenic phenotype could arise from polygenic interactions.

A de novo mutation in CYP21A2 gene in a case of in vitro fertilization

Congenital adrenal hyperplasia, one of the most frequent autosome recessive disorders, is caused by defects in steroidogenic enzymes involved in the cortisol biosynthesis. Approximately 95% of the cases are caused by abnormal function of the 21-hydroxylase enzyme. This deficiency leads to androgen excess, consequently, to virilization and rapid somatic growth with accelerated skeletal maturation. Mutations in CYP21A2 are responsible for different forms of 21-hydroxylase deficiency. Mild impairment in the enzymatic activity causes the non-classic or late-onset congenital adrenal hyperplasia that is observed with a prevalence of 1 in 1000 subjects in different populations. The present paper describes a de novo mutation that occurred in the paternal meiosis. The child, who was conceived by in vitro fertilization, presented with precocious puberty and diagnosed with non-classical 21-hydroxylase deficiency. DNA sequencing showed the compound heterozygosis for a de novo CYP21A1P/A2 chimeric gene and the p.Val281Leu mutation inherited from her mother, who was heterozygous for the mutation. The chimeric gene showed pseudogene-derived sequence from 5′-end to intron 3 and CYP21A2 sequences from intron 3 to 3′-end of the gene. Sequencing analysis of the father did not show any mutation. The multiplex ligation-dependent probe amplification (MLPA) assay did not indicate loss of DNA discarding gene deletion but confirmed the chimeric gene. In addition, supernumerary copies of CYP21A1P were observed for both parents and for the affect child. Since paternity has been confirmed, those results suggest that a de novo large gene conversion in the paternal meiosis could have occurred by misalignment of alleles bearing different copy numbers of genes in CYP21 locus.

Biochemical and genetic diagnosis of 21-hydroxylase deficiency

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is caused by mutations in the CYP21A2 gene and is often fatal in its classic forms if not treated with glucocorticoids. In contrast, non-classic CAH (NCCAH), with a prevalence from 0.1 % up to a few percentages in certain ethnic groups, only results in mild partial cortisol insufficiency and patients survive without treatment. Most NCCAH cases are never identified, but unnecessary suffering due to hyperandrogenism, especially in females, can be avoided by a correct diagnosis. A 17-hydroprogesterone (17OHP) level above 300 nmol/L indicates classic CAH while 30-300 nmol/L in adult males or females (follicular phase or if anovulatoric) indicates NCCAH. The gold standard for diagnosing NCCAH is the ACTH stimulation test. Deletion, large gene conversions, and nine microconversion-derived mutations are the most common CYP21A2 mutations. However, almost 200 rare mutations have been described. Since there is a good genotype-phenotype relationship, genotyping provides valuable diagnostic, as well as prognostic information. Neonatal screening for CAH is now performed in an increasing number of countries with the main goal of reducing mortality and morbidity due to salt-losing adrenal crises in the newborn period. In addition, screening may shorten the time to diagnosis in virilized girls. Neonatal screening misses some patients with milder classic CAH and most NCCAH cases. In conclusion, diagnosing classic CAH is life-saving, but diagnosing NCCAH is also important to prevent unnecessary suffering.

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.

21-Hydroxylase gene mutant allele CYP21A2*15 strongly linked to the resistant HLA haplotype B*14:02-DRB1*01:02 in chronic Chagas disease

We previously reported protective haplotype HLA-B*14:02-DRB1*01:02 against chronic Chagas disease in Bolivia. The V281L mutant allele of the 21-Hydroxylase gene, CYP21A2*15, is reported to be located in the Class III region of the Human leukocyte antigen region and linked to the haplotype HLA-B*14:02-DRB1*01:02. The mutant allele might play a primary role in the pathogenesis of chronic Chagas disease in the associated HLA region. We analyzed the frequency of this allele in the same subjects for the previous one. The statistical analysis showed a significant association of the CYP21A2*15 with resistance to severe chronic Chagas disease (OR=0.207273; Pv=0.0041). However, there is no significant tendency of the mutant gene contribution to the resistance after the elimination of the HLA-B*14:02-DRB1*01:02 linked mutants (OR=0.38; Pv=0.1533). Although the frequency of the CYP21A2*15 was small, we found no primary contribution of this mutation to the protection against chronic Chagas disease.

Congenital adrenal hyperplasia

Congenital adrenal hyperplasia consists of a heterogenous group of inherited disorders due to enzymatic defects in the biosynthetic pathway of cortisol and/or aldosterone. This results in glucocorticoid deficiency, mineralocorticoid deficiency, and androgen excess. 95% of CAH cases are due to 21-hydroxylase deficiency. Clinical forms range from the severe, classical CAH associated with complete loss of enzyme function, to milder, non-classical forms (NCAH). Androgen excess affects the pilosebaceous unit, causing cutaneous manifestations such as acne, androgenetic alopecia and hirsutism. Clinical differential diagnosis between NCAH and polycystic ovary syndrome may be difficult. In this review, the evaluation of patients with suspected CAH, the clinical presentation of CAH forms, with emphasis on the cutaneous manifestations of the disease, and available treatment options, will be discussed.

Genetic analysis of the CYP21A2 gene in neonatal dried blood spots from children with transiently elevated 17-hydroxyprogesterone

BACKGROUND

Neonatal screening for congenital adrenal hyperplasia (CAH) identifies a certain proportion of newborns with transient moderate elevation of 17-hydroxyprogesterone (17-OHP). These children require regular follow-up until normalization of their 17-OHP levels. We investigated the possibility of reducing the individuals' recall rates by using genetic methods on their original neonatal dried blood spots.

PATIENTS AND METHODS

We analysed neonatal dried blood spots from 753 subjects with transiently elevated levels of 17-OHP. The CYP21A2 gene was sequenced to detect point mutations, and the presence of CYP21A2 was further confirmed by two methods utilizing the difference between CYP21A2 and its CYP21A1P pseudogene in the sequence of exon 3 (8-bp deletion). The accuracy of the methods was verified using samples from 70 subjects with known CYP21A2 mutations and 181 healthy children.

RESULT

Among the 701 successfully sequenced samples from subjects with transiently elevated 17-OHP, 670 (95%) had no point mutations or novel variants in the CYP21A2 gene. We found no individuals carrying genotypes consistent with the diagnosis of CAH (i.e. homozygotes or compound heterozygotes for point mutations, large deletions or rearrangements). However, 21 heterozygous carriers of known point mutations that cause the classic and nonclassic forms of CAH were identified. Additionally, we detected eight heterozygous and two homozygous point variants with unknown functional significance.

CONCLUSION

Although CAH caused by 21-hydroxylase deficiency could be genetically excluded with a reasonable degree of confidence in 95% of the genotyped subjects that had transiently elevated 17-OHP, the performance of the tests was suboptimal when performed using dried blood spots and time-consuming in comparison with the current practice of repeated measurements of 17-OHP. The introduction of this method into clinical practice seems to be impractical at this stage.

Molecular genetic analysis of CYP21A2 gene in patients with congenital adrenal hyperplasia

CONTEXT

Congenital adrenal hyperplasia (CAH) is one of the inborn errors of metabolic disorder inherited in an autosomal recessive manner caused by the defects in the steroid 21 hydroxylase CYP21A2 gene. We analyzed the genotype of 62 patients with classic CAH.

AIMS

To find out the underlying mutations of CYP21A2 gene.

SETTINGS AND DESIGN

Cohort of CAH patients.

MATERIALS AND METHODS

Sixty-two patients with CAH were recruited from the endocrine clinic at AIIMS. Electrochemiluminiscence method was used for estimating the levels of cortisol. Radioimmunoassay kit-based method was used for estimating the 17 OHP levels. Polymerase chain reaction amplification was done using specific primers to amply the CYP21A2 gene.

STATISTICAL ANALYSIS USED

Statistical analysis was done by using Epi Info Version 3.5.1.2008.

RESULTS

Out of 62 patients, 50 were simple virilizers (SV) and 12 were salt wasters (SW). Fifty-six were females and six were males. Five 46, XX children were reared as males. Age at presentation varied from 8 months to 38 years. Molecular genetic analysis revealed that the highest number of patients harboured (In 2) IVS2-13 A/C > G (48%), followed by p.P30L (46%), p.Q318X (35%), (D 8 bp) deletion 8 bp (26%), p.I172N (26%), and p. R356W (20%) mutations.

CONCLUSION

This is among the few studies to analyze the mutational spectrum of CYP21A2 gene in a large CAH cohort from India. Molecular diagnosis of CYP21A2 gene should be considered as part of the CAH evaluation to assess the risk of the patients/parents/siblings and to offer genetic counseling.

Steroid 21 hydroxylase deficiency congenital adrenal hyperplasia

Steroid 21 hydroxylase deficiency is the most common form of congenital adrenal hyperplasia (CAH). The severity of this disorder depends on the extent of impaired enzymatic activity, which is caused by various mutations of the 21 hydroxylase gene. This article reviews adrenal steroidogenesis and the pathophysiology of 21 hydroxylase deficiency. The three forms of CAH are then discussed in terms of clinical presentation, diagnosis and treatment, and genetic basis. Prenatal diagnosis and treatment are also reviewed. The goal of therapy is to correct the deficiency in cortisol secretion and suppress androgen overproduction. Glucocorticoid replacement has been the mainstay of treatment for CAH, but new treatment strategies continue to be developed and studied.

The molecular biology, biochemistry, and physiology of human steroidogenesis and its disorders

Steroidogenesis entails processes by which cholesterol is converted to biologically active steroid hormones. Whereas most endocrine texts discuss adrenal, ovarian, testicular, placental, and other steroidogenic processes in a gland-specific fashion, steroidogenesis is better understood as a single process that is repeated in each gland with cell-type-specific variations on a single theme. Thus, understanding steroidogenesis is rooted in an understanding of the biochemistry of the various steroidogenic enzymes and cofactors and the genes that encode them. The first and rate-limiting step in steroidogenesis is the conversion of cholesterol to pregnenolone by a single enzyme, P450scc (CYP11A1), but this enzymatically complex step is subject to multiple regulatory mechanisms, yielding finely tuned quantitative regulation. Qualitative regulation determining the type of steroid to be produced is mediated by many enzymes and cofactors. Steroidogenic enzymes fall into two groups: cytochrome P450 enzymes and hydroxysteroid dehydrogenases. A cytochrome P450 may be either type 1 (in mitochondria) or type 2 (in endoplasmic reticulum), and a hydroxysteroid dehydrogenase may belong to either the aldo-keto reductase or short-chain dehydrogenase/reductase families. The activities of these enzymes are modulated by posttranslational modifications and by cofactors, especially electron-donating redox partners. The elucidation of the precise roles of these various enzymes and cofactors has been greatly facilitated by identifying the genetic bases of rare disorders of steroidogenesis. Some enzymes not principally involved in steroidogenesis may also catalyze extraglandular steroidogenesis, modulating the phenotype expected to result from some mutations. Understanding steroidogenesis is of fundamental importance to understanding disorders of sexual differentiation, reproduction, fertility, hypertension, obesity, and physiological homeostasis.

Cushing's disease in a patient with steroid 21-hydroxylase deficiency

Cushing's disease rarely appears as a consequence of hereditary disease. However, familial diseases with diminished glucocorticoid feedback are associated with secondary hypercorticotropinism and have been shown to give rise to pituitary adenomas. We here describe the rare case of a 30-year old female patient with congenital adrenal hyperplasia who also showed clinical signs and a typical history of hypercortisolism that was specified as Cushing's disease. After removal of a pituitary microadenoma, serum-cortisol levels fell below normal and the symptoms improved. However, after four years the menstrual cycle was irregular again and ACTH levels were in the upper range of normal. A corticotropin challenge showed a minor cortisol response but a marked increase in 17-hydroxyprogesterone serum concentrations. Genetic analysis revealed a homozygous mutation in exon 7 of the CYP21A2 gene (CTG>TTG, p.V281L). We conclude that a marked ACTH drive was able to override insufficient 21-hydroxylation and even to cause hypercortisolism. Although we describe a rare case, the impairment of the glucocorticoid feedback system in the context of congenital adrenal hyperplasia and other diseases may contribute to the development of secondary hypercorticotropinism as well as corticotropin producing adenomas.

The prevalence of non-classic adrenal hyperplasia among Turkish women with hyperandrogenism

The prevalence of non-classic adrenal hyperplasia (NCAH) among Turkish women with hirsutism has not been established so far. Thus, we aimed to evaluate the prevalence of 21-hydroxylase (21-OH) deficiency by ACTH stimulation test among hirsute women. The study population consisted of 285 premenopousal women, aged 16-46 years (mean: 23.2 ± 0.3). All were hirsute and hyperandrogenic. Androgen secreting tumors of the ovaries and the adrenal glands were excluded as well as thyroid dysfunction and hyperprolactinemia. All the patients were evaluated by 0.25 mg (i.v.) ACTH stimulation test and 17-OHP responses were obtained at 30 and 60 min. The diagnosis of NCAH due to 21-OH deficiency was considered in patients with the poststimulation 17-OHP level exceed 10 ng/ml. Six (2.1%) of the patients had NCAH due to 21-OH deficiency confirmed by genotyping. The rest of the patients were polycystic ovary syndrome (n = 166, 58.2%) and idiopathic hyperandrogenemia (n = 113, 39.7%). There were no patients with idiopathic hirsutism because patients with normal serum androgen levels were excluded. This first and most extensive national study investigating NCAH prevalence among Turkish population showed that NCAH is not prevalent in this population.

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.

Intron 2 Splice Mutation at CYP21 Gene in Patients with Congenital Adrenal Hyperplasia in the Republic of Macedonia

Congenital adrenal hyperplasia (CAH) is an autosomal recessive disorder. In 90-95% of cases it results from mutations in the gene for 21-hydroxylase (CYP21, also termed CYP21A2 and P450c21). The IVS-II-656 (C/A>G) mutation leaves ~2.0% enzyme activity, and comprises 25% of the classic CYP21 deficiency alleles and 51% of alleles in the salt-wasting form.

We performed direct molecular diagnosis of the IVS-II mutation in 41 Macedonian patients with different clinical forms of CAH and 55 of their healthy parents and siblings from 37 unrelated families, using the differential polymerase chain reaction/amplification created restriction site method (PCR/ACRS). The IVS-II mutation was detected in 41.5% patients (29.3% were homozygotes and 12.2% were heterozygotes). All homozygotes had a severe classical CAH phenotype (of which 91.7% were salt-wasting and 8.3% were simple virilizing). Three of the heterozygotes had a salt-wasting (SW) phenotype and were compound heterozygotes. The IVS-II mutation was also found in 30.9% of the family members (18.2% were homozygous and 12.7% were heterozygous) and none had any clinical manifestation. The frequency of the IVS-II mutation (41.5%) in these subjects was similar to that reported elsewhere.

An update to 21-hydroxylase deficient congenital adrenal hyperplasia

Congenital adrenal hyperplasia (CAH) due to deficiency of the enzyme 21-hydroxylase (21-OH) is distinguished in classical (C-CAH) and non-classical form (NC-CAH), and it is also one of the most common autosomal recessive inherited disorders in humans. The prevalence of C-CAH is between 1:10,000 and 1:15,000 among the live neonates of North America and Europe while the NC-CAH occurs in approximately 0.2% of the general white population. The highest incidence of CAH (1:282 and 1:2141, respectively) has been evaluated in Yupik Eskimos in Alaska and in the populations of the island La Reunion (France), while the lower was detected in New Zealand newborns (0.3%). Nowadays, it has been established that except for the adrenal cortex in CAH cases, the adrenal medulla was also affected. In human 21-OH deficient adrenal gland it has been discovered that not only the chromaffin cells formed extensive neurites, expanding between adrenocortical cells, but also that the adrenal androgens promote outgrowth, whereas glucocorticoids preserve neuroendocrine cells. It seems that normal cortisol secretion by the adrenal cortex is necessary for adrenomedullary organogenesis. The synthesis of 21-OH is controlled by the active CYP21A2 gene located at a distance of 30 kb from a highly homologous pseudogene designated CYP21A1P.

Steroid 21 hydroxylase deficiency congenital adrenal hyperplasia

Steroid 21 hydroxylase deficiency is the most common form of congenital adrenal hyperplasia (CAH). The severity of this disorder depends on the extent of impaired enzymatic activity, which is caused by various mutations of the 21 hydroxylase gene. This article reviews adrenal steroidogenesis and the pathophysiology of 21 hydroxylase deficiency. The three forms of CAH are then discussed in terms of clinical presentation, diagnosis and treatment, and genetic basis. Prenatal diagnosis and treatment are also reviewed. The goal of therapy is to correct the deficiency in cortisol secretion and suppress androgen overproduction. Glucocorticoid replacement has been the mainstay of treatment for CAH, but new treatment strategies continue to be developed and studied.

Nonclassic adrenal hyperplasia

Nonclassic adrenal hyperplasia is most commonly attributable to mutations in CYP21A2 (also termed CYP21) encoding steroid 21-hydroxylase. Partial deficiency of this enzyme causes an imbalance in cortisol synthesis with consequent adrenal androgen excess. Unlike more severe forms of congenital adrenal hyperplasia, this condition is rarely recognized in infants, but rather is a potential cause of premature adrenarche and pubarche in children, virilization in young women, and variable symptoms in young men. This article will review relevant clinical, hormonal and genetic aspects of nonclassic adrenal hyperplasia.

Congenital adrenal hyperplasia in adults

Hyperandrogenism in congenital adrenal hyperplasia (CAH) results from overstimulation of adrenocorticotropic-driven androgen production in the adrenal cortex due to lack of cortisol feedback. The classical form is characterized by more-severe symptoms of hyperandrogenism, including virilization of the female genitalia. The milder nonclassical form presents with postnatal symptoms of hyperandrogenism. Presenting symptoms in adulthood may include acne, male-pattern alopecia, hirsutism, irregular menses/amenorrhea or infertility. The goal of therapy in CAH is to both correct the deficiency in cortisol secretion and suppress androgen overproduction. Glucocorticoid replacement has been the mainstay of treatment for CAH but new treatment strategies continue to be developed and studied.

The prevalence of non-classical congenital adrenal hyperplasia due to 21-hydroxylase deficiency in Greek women with hirsutism and polycystic ovary syndrome

The study was aimed to find out the prevalence of non-classical congenital adrenal hyperplasia (NC-CAH) due to 21-hydroxylase deficiency (21-OHdef) among Greek women with hirsutism and polycystic ovary syndrome (PCOS) and to compare the results of ACTH stimulated 17-hydroxyprogesterone 60 min (17-OHP60) values, with human leukocyte antigens (HLA) phenotypes, in any patient diagnosed as having NC-CAH. One hundred and seven women with hirsutism and PCOS were included in the study. All were presented at the Reproductive Endocrinology Outpatient Clinic with hirsutism and PCOS. After ACTH stimulation test, 10 women were diagnosed as having NC-CAH because of high 17-OHP60 values >or=36 nmol/l, and 97 as having PCOS. Ten (10.3%) of the 97 women presented hormonal findings compatible with adrenal hyper-response due to ACTH testing, because of hyperstimulated 17-OHP60 values >or=21 nmol/l and <32 nmol/l. The HLA typing of 10 patients with NC-CAH revealed the phenotypes B14, DR1, B35, B7 and B44 which present positively genetic linkage disequilibrium with 21-OHdef, as reported in the literature.

IN CONCLUSION

In Greek women with hirsutism and PCOS we have found that: a. The prevalence of NC-CAH among these women is relatively high and reaches at 10%. b. The HLA phenotypes B(14), DR(1), B(35), B(7) and B44 were found in high frequency in these NC-CAH patients. c. Adrenal NC-CAH due to 21-OHdef as well as adrenal hyperactivity, revealed after ACTH testing, constitutes an important reason of hirsutism and PCOS in these Greek women and both reach a rate of 20%.

A 31-year-old woman with infertility and polycystic ovaries diagnosed with non-classic congenital adrenal hyperplasia due to a novel CYP21 mutation

A 31-yr-old woman presenting with a history of hirsutism, amenorrhea, and infertility was previously assumed to have polycystic ovary syndrome. A new gynecological-endocrine evaluation demonstrated elevated testosterone/SHBG ratio, serum 17-hydroxyprogesterone (17-OHP), and urinary pregnantriol. She was diagnosed with non-classic congenital adrenal hyperplasia. In spite of treatment with dexamethasone and fludrocortisone in doses that suppressed adrenal androgens and 17-OHP into normal range or below, she did not ovulate. Clomiphene citrate and then FSH/hCG treatment in several cycles gave no consistent ovulation. Progesterone levels remained elevated throughout the cycles indicating a possible contribution from the adrenals. Oral glucose tolerance was normal, but the homeostasis model assessment index indicated insulin resistance. With metformin 1500 mg daily the index decreased remarkably from 2.77 to 0.96 with a few ovulations but no pregnancy occurred. Three cycles of IVF treatment thereafter were unsuccessful. Three months after the last in vitro fertilization (IVF) cycle, still on dexamethasone, fludrocortisone, and metformin, her menstruations became regular and she thereafter became pregnant. During pregnancy metformin was discontinued and dexamethasone replaced with prednisolone. Mild gestational diabetes developed and insulin was given. A healthy boy was born at term by elective Cesarean section. A CYP21- gene analysis had not indicated any of the known mutations but after gene sequencing a novel mutation was found, namely R233G. This case confirms the necessity of adding an analysis of 17-OHP when evaluating women with hirsutism and menstrual disturbances and if an elevated value is found, the advantage of performing a mutation analysis to facilitate counseling and decisions on treatment.

Basic concepts and recent developments in human steroid hormone biosynthesis

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

Microconversion between CYP21A2 and CYP21A1P promoter regions causes the nonclassical form of 21-hydroxylase deficiency

CONTEXT

Most mutations causing 21-hydroxylase deficiency originate from microconversions between CYP21 pseudogenes and active genes. However, around 20% of the alleles in the nonclassical form (NC-21OHD) remain without identified mutations, suggesting the involvement of regulatory regions. The pseudogene promoter is 80% less active than the CYP21A2 due to the presence of -126C>T, -113G>A, -110T>C, and -103A>G mutations. Additionally, mutations in the steroidogenic factor-1 binding sites of the CYP21 distal regulatory region, located at 4676 bases upstream from the cap site of the CYP21A2 gene, decrease its transcription to 35%.

OBJECTIVE

The objective of the study was to investigate the CYP21A2 promoter/regulatory regions in NC-21OHD patients with undetermined genotype.

SUBJECTS

The study included 17 NC-21OHD patients and 50 controls.

METHODS

Promoter/regulatory regions were sequenced from peripheral leukocytes' genomic DNA. The identified substitutions were evaluated through EMSA using -132/-97 wild-type and mutant probes and nuclear extracts from NCI-H295A cells. Transcriptional activity studies were performed with wild-type and mutant constructions transfected in NCI-H295A cells.

RESULTS

No mutations were identified in the distal regulatory regions. The -126C>T, -113G>A, -110T>C promoter mutations were found in compound heterozygosity with the V281L mutation in one patient and the -126C>T mutation in compound heterozygosity with the I2 splice in another. The -126T mutation decreases the transcriptional activity to 52%, compatible with the patient's nonclassical phenotype. EMSA demonstrated that the -132/-121 region is important for the DNA interaction with the specificity protein-1 transcription factor.

CONCLUSION

Microconversions between CYP21A2 and CYP21A1P promoters could be involved in the nonclassical phenotype. Therefore CYP21A2 promoter analysis should be included in genetic studies of 21OHD.

Prenatal diagnosis and treatment of congenital adrenal hyperplasia owing to 21-hydroxylase deficiency

Classical forms of congenital adrenal hyperplasia are caused by a severe deficiency of 21-hydroxylase, an enzyme involved in steroid biosynthesis, which triggers excessive androgen production before birth. Affected females experience virilization both physically and psychologically. Prenatal diagnosis and treatment of congenital adrenal hyperplasia has been implemented for more than 20 years. In utero gene-specific diagnosis is now feasible for fetal cell samples derived from chorionic villi or amniotic cells in culture, and this gene-specific diagnosis guides the treatment of the affected female fetus. Appropriate dexamethasone administration to the at-risk pregnant mother is effective in reducing genital virilization in the fetus, and thus avoids unnecessary genitoplasty in affected females. Current data from large human studies show the benefit and safety of prenatal treatment. Long-term follow-up of the safety of prenatal treatment is currently underway. This practice is a rare example of effective prenatal treatment to prevent a malformation caused by an inborn error of metabolism.

Ethnic-specific distribution of mutations in 716 patients with congenital adrenal hyperplasia owing to 21-hydroxylase deficiency

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21OHD) occurs worldwide. The most common mutations in the CYP21A2 gene in 716 unrelated patients were analyzed and the mutations were grouped by ethnicity, as defined through self-declaration corroborated by review of pedigrees extending to two or three generations. Prevalent allelic mutations and genotypes were found to vary significantly among ethnic groups, and the predominance of the prevalent mutations and genotypes in several of these populations was significant. There are ethnic-specific mutations in the CYP21A2 gene. A large deletion is prevalent in the Anglo-Saxons; a V281L (1685 G to T) mutation is prevalent in Ashkenazi Jews; an R356W (2109 G to A) mutation is prevalent in the Croatians; an IVS2 AS -13 (A/C to G) mutation is prevalent in the Iranians and Yupik-speaking Eskimos of Western Alaska; and a Q318X (1994 C to T) mutation is prevalent in East Indians. Genotype/phenotype non-correlation was seen when at least one IVS2 AS -13 (A/C to G) mutation in the CYP21A2 gene was present.

Gestational age correlates to genotype in girls with CYP21 deficiency

CONTEXT

The mechanisms behind onset of labor and prolongation of pregnancy are not fully understood, but steroid hormones are thought to contribute. 17-Hydroxyprogesterone has been shown to prolong pregnancy in humans. Male fetuses have been reported to have longer gestation than females.

OBJECTIVE

The objective of the study was to investigate whether severity of 21-hydroxylase gene (CYP21) deficiency in fetuses with congenital adrenal hyperplasia (CAH) correlates with length of pregnancy.

DESIGN AND SUBJECTS

The gestational age (GA) of a cohort of CAH patients born between 1978 and 2004 was studied retrospectively. The GA was correlated to the severity of disease indicated by CYP21 genotype in 114 patients. The results were compared with respect to sex and the normal Swedish population data.

RESULTS

In female fetuses with CAH, we found a correlation between GA and CYP21 genotype. Females with the most severe form of the disease, null mutation, had the longest GA and differed significantly from the normal population. No difference between the sexes was detected for fetuses with CAH as a group. There were no significant differences between CYP21 genotype groups for males.

CONCLUSIONS

Female patients with severe CYP21 deficiency had longer GA than patients with the milder form of the disease, indicating that androgen excess, increased 17-hydroxyprogesterone levels, or cortisol deficiency or a combination of these factors is of importance for prolongation of pregnancy. The same correlation was not observed for male patients. The results of this study support the notion that steroid hormones affect the prolongation of pregnancy or onset of labor or both.

Characterization of novel missense mutations in CYP21 causing congenital adrenal hyperplasia

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency is the most common inherited disorder of steroid metabolism, with an incidence of 1/10,000 in the general Caucasian population. Although most patients carry a deletion of the CYP21 gene or any of nine pseudogene-derived point mutations, the number of reported rare mutations continues to increase, and consist today of more than 80 different point mutations. In this study, we report the characterization of four additional missense mutations in CYP21. Two of these, L166P and A391T, are novel missense mutations, whereas the R479L and R483Q mutations have been detected previously. Functional assays of mutagenized CYP21 were performed in transiently transfected mammalian cells in vitro, and enzymatic ability of substrate conversion of the two natural substrates of CYP21-17-hydroxyprogesterone and progesterone-was determined. All mutants displayed reduced in vitro enzyme activities compared with wild type, but to different extents, corresponding to clinical phenotypes that span the whole spectrum of disease severity. Functional studies are important to further establish the relationships between genotype and clinical phenotype as well as in vitro CYP21 activity in congenital adrenal hyperplasia due to 21-hydroxylase deficiency. This has relevance for diagnosis, prognosis, and genetic counseling for affected families.

Extensive clinical experience: nonclassical 21-hydroxylase deficiency

CONTEXT

Nonclassical congenital adrenal hyperplasia (CAH) owing to steroid 21-hydroxylase deficiency (NC21OHD) is the most frequent of all autosomal recessive genetic diseases, occurring in one in 100 persons in the heterogeneous New York City population. NC21OHD occurs with increased frequency in certain ethnic groups, such as Ashkenazi Jews, in whom one in 27 express the disease. NC21OHD is underdiagnosed in both male and female patients with hyperandrogenic symptoms because hormonal abnormalities in NC21OHD are only mild to moderate, not severe as in the classical form of CAH. Unlike classical CAH, NC21OHD is not associated with ambiguous genitalia of the newborn female.

MAIN OUTCOME MEASURES

The hyperandrogenic symptoms include advanced bone age, early pubic hair, precocious puberty, tall stature, and early arrest of growth in children; infertility, cystic acne, and short stature in both adult males and females; hirsutism, frontal balding, polycystic ovaries, and irregular menstrual periods in females; and testicular adrenal rest tissue in males.

CONCLUSIONS

The signs and symptoms of hyperandrogenism are reversed with dexamethasone treatment.

Molecular model of human CYP21 based on mammalian CYP2C5: structural features correlate with clinical severity of mutations causing congenital adrenal hyperplasia

Enhanced understanding of structure-function relationships of human 21-hydroxylase, CYP21, is required to better understand the molecular causes of congenital adrenal hyperplasia. To this end, a structural model of human CYP21 was calculated based on the crystal structure of rabbit CYP2C5. All but two known allelic variants of missense type, a total of 60 disease-causing mutations and six normal variants, were analyzed using this model. A structural explanation for the corresponding phenotype was found for all but two mutants for which available clinical data are also discrepant with in vitro enzyme activity. Calculations of protein stability of modeled mutants were found to correlate inversely with the corresponding clinical severity. Putative structurally important residues were identified to be involved in heme and substrate binding, redox partner interaction, and enzyme catalysis using docking calculations and analysis of structurally determined homologous cytochrome P450s (CYPs). Functional and structural consequences of seven novel mutations, V139E, C147R, R233G, T295N, L308F, R366C, and M473I, detected in Scandinavian patients with suspected congenital adrenal hyperplasia of different severity, were predicted using molecular modeling. Structural features deduced from the models are in good correlation with clinical severity of CYP21 mutants, which shows the applicability of a modeling approach in assessment of new CYP21 mutations.

Functional studies of two novel and two rare mutations in the 21-hydroxylase gene

Congenital adrenal hyperplasia (CAH) is most commonly due to 21-hydroxylase deficiency and presents with a wide spectrum of clinical manifestations, from prenatal virilization and salt-wasting in the neonatal period to precocious pubarche and late-onset hyperandrogenic symptoms during adulthood. A limited number of mutations account for the majority of all mutated alleles, but a growing number of rare mutations are responsible for the disease in some patients. By sequence analysis of the CYP21A2 gene, we identified two novel (I171N and L446P) and two rare (R341P and R426H) mutations in seven Italian patients with CAH. One of the patients was diagnosed with mild non-classical CAH and was found to be a compound heterozygote (I171N/V281L), while all other patients showed severe phenotypes with latent or manifest salt-wasting. The residual activities measured after expression of the four mutant enzymes in COS-1 cells were all below 1% towards both natural substrates (17-OH-progesterone and progesterone) compared with the wild-type protein. All four mutations are, thus, associated with severe enzyme deficiency and are predicted to cause classic CAH if found in trans with other mutations causing severe enzyme deficiency.

Diagnosis and management of congenital adrenal hyperplasia

Congenital adrenal hyperplasia is the name applied to a class of autosomal recessive disorders resulting from deficiency of one of five enzymes necessary for cortisol synthesis by the adrenal cortex. Congenital adrenal hyperplasia is most often attributable to steroid 21-hydroxylase deficiency, accounting for more than 90% of cases. This discussion will be limited to the most common form of the disease, highlighting methods of diagnostic screening and challenges in disease management.

An update of congenital adrenal hyperplasia

Congenital adrenal hyperplasia (CAH) is a family of autosomal recessive disorders caused by mutations that encode for enzymes involved in one of the various steps of adrenal steroid synthesis. These defects result in the absence or the decreased synthesis of cortisol from its cholesterol precursor. The anterior pituitary secretes excess adrenocorticotrophic hormone (ACTH) via feedback regulation by cortisol, which results in overstimulation of the adrenals and causes hyperplasia. Symptoms due to CAH can vary from mild to severe depending on the degree of ensymatic defect. In the classical form of CAH, there is a severe enzymatic defect owing to mutations in the CYP21 gene. Classically affected female fetuses undergo virilization of the genitalia prenatally and present with genital ambiguity at birth; however, prenatal treatment of CAH with dexamethasone to prevent ambiguity has been successfully utilized for over a decade. In the less severe, late-onset form of CAH, prenatal virilization does not occur. The milder enzyme deficiency was termed nonclassical 21-hydroxylase deficiency (NC21OHD) in 1979 and was later found to be the most common autosomal recessive disorder in humans. Disease frequency of NC21OHD varies between ethnic groups with the highest ethnic-specific disease frequency in Ashkenazi Jews at 1/27. NC21OHD is diagnosed by serum elevations of 17-OHP that plot on a nomogram between the range for unaffected individuals and levels observed for classical CAH and is typically confirmed with molecular genetic analysis. Similar to classical CAH, nonclassical 21-hydroxylase deficiency may cause premature development of pubic hair, advanced bone age, accelerated linear growth velocity and diminished final height in both males and females. Severe cystic acne has also been attributed to nonclassical CAH. Women may present with symptoms of androgen excess, including hirsutism, temporal baldness, and infertility. Menarche in females may be normal or delayed and secondary amenorrhea is a frequent occurrence. Polycystic ovary syndrome may also be seen in these patients. In males, early beard growth, acne, and growth spurt may prompt the diagnosis of NC21OHD. Although many males appear to be asymptomatic, they may present with oligozoospermia or diminished fertility. Individuals presenting to dermatology and infertility clinics with symptoms of hyperandrogenemia are rarely screened for NC21OHD. However, with hormonal and molecular genetic screening, previously undiagnosed patients may be identified and can therefore receive glucocorticoid treatment, which has been shown to reverse symptoms within 3 months.

21-Hydroxylase deficiency: from molecular genetics to clinical presentation

Congenital adrenal hyperplasia due to deficiency of the enzyme 21-hydroxylase (21-OH), a cytochrome P450 enzyme located in the endoplasmic reticulum and which catalyzes the conversion of 17-hydroxyprogesterone to 11-deoxycortisol and progestene to deoxycorticosterone, is distinguished in its classical and non-classical form and is also one of the most common autosomal recessive inherited diseases in humans. The classical form appears in a rate between 1:5000 and 1:15,000 among the live neonates of North America and Europe, while the non-classical form occurs in approximately 0.2% of the general white population. This rate is especially high between the Ahskenazi Jews and a part (ie Italians, Hispanics) of the Mediterranean populations. Three alleles are associated with the 21-OH locus and can be combined in several ways in individuals who are either unaffected, heterozygote carriers, or affected with classical or non-classical disease. Variable signs and symptoms of hyperandrogenism, such as hirsutism, acne, virilization of the external genitalia and/or the body, short stature, menstrual irregularities, are common to both types of the disorder. Among the genes responsible for the synthesis of the enzyme 21-OH and the antigens of HLA system, exist both a proven genetic linkage and a proven genetic linkage disequilibrium. HLA-Bw47, HLAB5 and HLA-B35 are the most common haplotypes usually met in the classical form, while the haplotype HLA-B14DR1 is the most recurrent in the non-classical form of the disease. The significant advances in molecular biology and gene analysis over the past two decades have led to the development of novel sensitive methods of DNA analysis and study, such as polymerase chain reaction and southern blot analysis. Thus, it has been revealed that the synthesis of enzyme 21-OH is controlled by two genes, the active CYP21B gene and the CYP21A pseudogene. All three forms of the disease have a known sequence of gene changes owing to mutations in isolated proteins or whole series of genes due to translocations or deletions of genetic material.

The prevalence, molecular analysis and HLA typing of late-onset 21-hydroxylase deficiency in Turkish woman with hirsutism and polycystic ovary

We studied the incidence of late-onset congenital adrenal hyperplasia (LOCAH) due to 2l-hydroxylase (21-OH) deficiency, its molecular genotype expression, and its association with the major histocompatibility complex in 61 women with hirsutism and polycystic ovary. Ultrasound, clinical and hormonal parameters were used to define polycystic ovary syndrome (PCOS). Baseline and ACTH stimulated 17alpha-hydroxyprogesterone (17-OHP) levels were measured for screening of LOCAH during follicular phase. Forty-one women were diagnosed as having PCOS (67%) and 20 women were diagnosed as having had LOCAH due to 2l-OH deficiency (33%). In LOCAH patients, the most common mutation (Val281-Leu, V281L) was found in 10 patients (7 heterozygous/3 homozygous). The frequency of V281L mutation was found as 32.5% in 20 patients. All patients with the V281L mutation presented HLA-B14 (100%) and six of them presented DR1 (60%), confirming that LOCAH is linked to the histocompatibility complex. Although molecular analysis is a better and more accurate means for an exact and precise definition of LOCAH, it is not routinely available in our country. So, ACTH stimulation test combined with HLA-B14 typing should be more widely utilized in these patients. As a result, LOCAH due to 21-OH deficiency is unexpectedly high in Turkish patients with hirsutism and PCO.

Phenotype and genotype correlation of the microconversion from the CYP21A1P to the CYP21A2 gene in congenital adrenal hyperplasia

Deficiency of 21-hydroxylase is the most common form of congenital adrenal hyperplasia (CAH-21OH). We determined by allele-specific PCR the frequency of microconversion in the CYP21A2 gene in 50 Brazilian patients with the classical (salt wasting: SW and simple virilizing: SV) forms and nonclassical (NC) form of CAH-21OH and correlated genotype with phenotype. Genotypes were classified into three mutation groups (A, B, and C) based on the amount of enzymatic activity in in vitro studies using adrenal cells. In 94 unrelated alleles, we diagnosed 76% of the affected alleles after screening for 7 microconversions. The most frequent point mutations observed in this series were I172N (19%), V281L (18%), and IVS2,A/C>G,-12 (15%). In the SW form, the most frequent mutation was IVS2,A/C>G,-12 (38%), in the SV form it was I172N (53%), and in the NC form it was V281L (57.7%). We observed a good correlation between genotype and phenotype. Discordance between genotype and phenotype was found in one SV patient with a mild mutation in one of the alleles (R356W/V281L). However, we cannot rule out the presence of an additional mutation in these alleles. We also observed a good correlation of genotype with 17alpha-hydroxyprogesterone, testosterone, and androstenedione levels. The severity of external genitalia virilization correlated with the severity of mutation. In conclusion, the frequencies described in the present study did not differ from worldwide studies, including the Brazilian population. The few differences observed may reflect individual sample variations. This new Brazilian cohort study suggests the presence of new mutations in Brazilian patients with different forms of CAH-21OH.