Mutational spectrum of steroid 21-hydroxylase and the genotype-phenotype association in Middle European patients with congenital adrenal hyperplasia

Cost-effective genotyping for classical congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21-OHD) in resource-poor settings: multiplex ligation probe amplification (MLPA) with/without sequential next-generation sequencing (NGS)

PURPOSE

Genotyping of classic congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21-OHD) is becoming increasingly significant beyond prenatal counseling in the current era of emerging gene therapy/editing technologies. While the knowledge of common variants helps in designing cost-effective genotyping strategies, limited data are currently available from the Indian subcontinent, especially South India, mainly due to financial constraints. The aim of this study is to assess the genotype of individuals with classic CAH from a South Indian cohort in a cost-effective manner.

METHODS

The genotypes of 46 unrelated subjects with classic CAH were studied through initial multiplex ligation-dependent probe amplification (MLPA) using the SALSA MLPA Probe-mix P050 CAH (MRC Holland). Next-generation sequencing (NGS) was done in 10 subjects, as their MLPA was either negative or showed heterozygous variants.

RESULTS

The common variants observed in our study population of 46 subjects were large deletions (35.8%), intron 2 variant [c.293-13A/C > G] (35.8%), 8 bp del [c.332_339del p.(Gly111Valfs*21)] (7.7%), and R356W [c.1069 C > T p.(Arg357Trp)] (6.6%). MLPA alone detected pathogenic variants in 78.2% of the initial study samples (36/46). Sequential NGS resulted in a 100% detection rate in our study population.

CONCLUSION

MLPA appears to be an effective first genotyping modality for this South Indian cohort due to the high prevalence of large deletions and common variants. MLPA as a first initial screening genotyping test with sequential NGS when required may be a cost-effective and highly sensitive approach to CYP21A2 genotyping in our part of the world and in resource-poor settings.

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

OBJECTIVE

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

DESIGN AND METHODS

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

RESULTS

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

CONCLUSION

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

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.

First insights into the genetics of 21-hydroxylase deficiency in the Roma population

BACKGROUND

21-hydroxylase deficiency (21OHD) is an autosomal recessive disorder with an incidence of 1:10,000-1:20,000 and is the result of various mutations in the CYP21A2 gene. 21OHD has been described in many different populations, but it has not been studied in Roma individuals so far. The aim of the study was to analyse the genotype in Roma patients with 21OHD and the prevalence of the disease in the Roma population of North Macedonia.

METHODS

Molecular analysis of the nine most frequent CYP21A2 mutations in all known Roma patients with CAH in North Macedonia, relatives and healthy individuals of Roma ancestry, using the PCR/ACRS method.

RESULTS

Ten Roma patients with 21OHD were identified, of which nine had the salt-wasting and one had the simple virilizing form. Calculated incidence of 21OHD in the North Macedonian Roma population was 1:3375. Interestingly, 9/10 patients (90%) were homozygous for the In2G splicing mutation (293-13A/C > G). Standard therapy with hydrocortisone and fludrocortisone had been introduced according to the guidelines. In 16 healthy relatives investigated for CYP21A2 mutations, heterozygosity for the In2G mutation was detected in 13/32 (40.6%) alleles. In 100 healthy Roma individuals, none related to the analysed families, no CYP21A2 mutations were detected.

CONCLUSION

The Roma population in North Macedonia had a very high incidence of classic 21OHD. Almost all patients had the severe salt-wasting form and the In2G/In2G genotype.

A novel 9 bp deletion (c.1271_1279delGTGCCCGCG) in exon 10 of CYP21A2 gene causing severe congenital adrenal hyperplasia

BACKGROUND

Congenital adrenal hyperplasia (CAH) is an autosomal recessive disorder of adrenal steroidogenesis with a broad spectrum of clinical presentations, ranging from the severe classical salt-wasting (SW) and simple-virilizing (SV) form, to the mild nonclassical form. A large variety of CYP21A2 genotypes in correlation with phenotype have been described.

MATERIALS AND METHODS

DNA samples from a 14-day-old male newborn with clinical and laboratory signs of SW CAH and family members were subjected for molecular analysis of the nine most common point CYP21A2 mutations by ACRS/PCR method. Direct DNA sequencing of the whole CYP21A2 gene was performed to detect the second mutant allele in the patient. The in silico predicting analysis and the crystal structure analysis of the mutated CYP21A2 protein have been performed.

RESULTS

Molecular analysis confirmed that the patient was compound heterozygote carrying p.Q318X mutation inherited from the mother and a novel c.1271_1279delGTGCCCGCG (p.G424_R426del) variant in exon 10 inherited from the father. The in silico predicting software tools classified the novel mutation as pathogenic. Crystal structure analysis showed that the three residues affected by the novel in-frame deletion form several hydrogen bonds that could lead to impaired stability and function of the CYP21A2 protein. These findings were concordant with the patient's phenotype. The need of several molecular methods to elucidate the genotype in this patient has also been discussed.

CONCLUSIONS

A novel 9 bp deletion in CYP21A2 gene with predicted pathogenic effect on the enzyme activity was detected in neonatal patient causing severe SW CAH.

Nonvirilized Genitalia in 3 Female Newborns With the Salt-Wasting Congenital Adrenal Hyperplasia Phenotype

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency, a form of primary adrenal insufficiency characterized by impaired cortisol secretion and elevated androgen production, is the leading cause of atypical genitalia in the female newborn. Females with classic CAH, either salt-wasting or simple-virilizing form, usually present at birth with atypical genitalia ranging from clitoromegaly to male-appearing genitalia, due to in utero to elevated androgens (androstenedione and testosterone). Females with mild nonclassic CAH usually present with typical genitalia. Proving the importance of always keeping an open mind for exceptions to the rule, we report on 3 female newborns who presented with the nonvirilized genitalia, salt-wasting CAH phenotype and genotype most consistent with simple-virilizing CAH. It is only through a positive newborn screen identifying the females with CAH that they were diagnosed before developing adrenal and/or salt-wasting crisis.

Characteristics of In2G Variant in Congenital Adrenal Hyperplasia Due to 21-Hydroxylase Deficiency

Substantial research has been performed during the last decades on the clinical and genetic variability of congenital adrenal hyperplasia (CAH) and its most common form, 21-hydroxylase deficiency (21OHD). CAH is one of the most prevalent autosomal recessive diseases in humans, and it can be divided into classic-further subdivided into salt wasting (SW) and simple virilizing (SV)-and non-classic (NC) forms. Pathogenic variants of CYP21A2 gene, encoding the 21-hydroxylase enzyme, have been reported with variable prevalence in different populations. NM_000500.9:c.293-13C/A>G (In2G) variant represents the most common CYP21A2 gene changes related to the classic 21OHD form. However, the phenotype of In2G carriers is variable depending on the variant homozygous/heterozygous status and combination with other CYP21A2 pathogenic variants. In addition, identical genotypes, harboring the homozygous In2G variant, can present with variable phenotypes including the SW and SV or rarely NC form of the disease. Here, we analyze and present the clinical aspects, genotype/phenotype correlations, and other characteristics related to the CYP21A2 In2G variant.

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.

Clinical and hormonal characteristics in heterozygote carriers of congenital adrenal hyperplasia

Non-classical congenital adrenal hyperplasia (NC-CAH) includes a group of genetic disorders due to a broad class of CYP21A2 variants identifying a disease-causing 'C' genotype. The heterozygous carriers of CYP21 mutations are at increased risk of developing clinically evident hyperandrogenism, even though clinical and laboratory characteristics are still underestimated. With the aim of obtaining a more accurate delineation of the phenotype of heterozygous carrier of CAH, we analyzed clinical, biochemical and molecular characteristics in a cohort of Sicilian subjects. Fifty-seven females with biallelic and monoallelic CYP21A2 variants classifying NC-CAH (24) and heterozygous carriers of CAH (33), respectively were selected. Forty-four females age-matched healthy controls were also enrolled and genotyped for CYP21A2. Clinical, hormonal and genetic data were collected. CYP21A2 monoallelic mutations, defining the heterozygous carriers state, were identified in subjects with clinical features including hirsutism, oligomenorrhoea, overweight and a PCO-like phenotype, particularly occurring in the age of adolescence. Consistently, levels of 17OHP and cortisol were found to be significantly different from NC-CAH. Overall, some clinical and laboratory findings including oligomenorrhea and 17OHP/cortisol ratio were observed as independent markers associated with carriers of CAH. Here we report a high prevalence of late-onset signs of polycystic ovary syndrome (PCOS) and hyperandrogenism in heterozygous carriers. The 17OHP/cortisol ratio may be a predictive tool to identify the carriers of CAH, even though specific cut-off values have not yet been identified.

CYP21A2 Gene Pathogenic Variants: A Multicenter Study on Genotype-Phenotype Correlation from a Portuguese Pediatric Cohort

BACKGROUND

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21OHD) is an autosomal recessive disorder characterized by 3 overlapping phenotypes: salt-wasting (SW), simple virilizing (SV), and non-classic (NC). We aimed at conducting a nationwide genotype description of the CAH pediatric patients and to establish their genotype-phenotype correlation.

METHODS

CAH patients were recruited from Portuguese pediatric endocrinology centers and classified as SW, SV, or NC. Genetic analysis was performed by polymerase chain reaction (sequence specific primer, restriction fragment length polymorphism) or direct Sanger sequencing. Genotypes were categorized into 4 groups (0, A, B, and C), according to their predicted enzymatic activity. In each group, the expected phenotype was compared to the observed phenotype to assess the genotype-phenotype correlation.

RESULTS

Our cohort comprises 212 unrelated pediatric CAH patients (29% SW, 11% SV, 60% NC). The most common pathogenic variant was p.(Val282Leu; 41.3% of the 424 alleles analyzed). The p.(Val282Leu) variant, together with c.293-13A/C>G, p.(Ile173Asn), p.(Leu308Thr), p.(Gln319*), and large deletions/conversions were responsible for 86.4% of the mutated alleles. Patients' stratification by disease subtype revealed that the most frequent pathogenic variants were c.293-13A/C>G in SW (31.1%), p.(Ile173Asn) in SV (46.9%), and p.(Val282Leu) in NC (69.5%). The most common genotype was homozygosity for p.(Val282Leu; 33.0%). Moreover, we found 2 novel variants: p.(Ile161Thr) and p.(Trp202Arg), in exons 4 and 5, respectively. The global genotype-phenotype correlation was 92.4%. Group B (associated with the SV form) showed the lowest genotype-phenotype correlation (80%).

CONCLUSION

Our cohort has one of the largest NC CAH pediatric populations described. We emphasize the high frequency of the p.(Val282Leu) variant and the very high genotype-phenotype correlation observed.

21-Hydroxylase deficiency: Mutational spectrum and Genotype-Phenotype relations analyses by next-generation sequencing and multiplex ligation-dependent probe amplification

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21OHD) is autosomal recessive disorder of cortisol biosynthesis. Genetic defects in CYP21A2 cause 21OHD. The aim of this study was to determine spectrum of mutations in CYP21A2 in a large cohort and analyze the genotype-phenotype correlation to assess predictive characteristics of genotype. We investigated a total of 113 patients with 21OHD. Next-generation sequencing and Multiplex ligation-dependent probe amplification of the CYP21A2 gene were performed in patients and their parents. The genotypes were categorized into Groups 0, A, B, and C according to the residual 21-hydroxylase activities. In this study, the group A was divided into two subgroups as A1 and A2. Three novel variants were found. The genotype-phenotype correlation of the mutation classification was 91.5%. Positive predictivity of subgroups A1 was higher than groups A and subgroups A2. Our study reports genotype-phenotype correlations in the largest 21OHD cohort in Turkey. This correlation sustained when we analyzed our data in combination with metadata from other published studies. This study confirms that CYP21A2 genotyping with next-generation sequencing and MLPA can accurately and reliably confirm the diagnosis of 21OHD. We propose a new classification by dividing group A into two new subgroups to better predict the phenotype. In light of this very high genotype-phenotype correlation, with their ever-increasing availability, declining cost, and turnaround time, we propose that molecular genetic studies can be more economical and practical alternative to the current initial diagnostic laboratory studies based on assays of intermediary steroid metabolites.

The impact of CYP21A2 (P30L/I172N) genotype on female fertility in one family

BACKGROUND

The simple virilizing (SV) form of congenital adrenal hyperplasia (CAH) is an autosomal recessive disorder usually caused by steroid 21-hydroxylase deficiency due to I172N missense mutation at the CYP21A2 gene. Clinical presentation encompasses virilization of external genitalia in newborn females and pseudoprecocious puberty in both sexes, due to reactive androgen overproduction. The aim of this study was to present two sisters with an SV form of CAH and distinctive genotype, detected and treated since childhood with a poor compliance and poor metabolic control hindering the fertility.

CASE PRESENTATION

We retrospectively reviewed the clinical, biochemical, and molecular data of two sisters with CAH a 46,XX karyotype when they reached an age of 35 and 38 years, respectively, and were attempting conception for several years. They had been diagnosed with SV form of CAH at the age of 7 and 9 years, respectively, by the standard clinical and biochemical procedures, presenting with severe virilization due to androgen excess. Follow-up was performed through standard methods of measurement of 17-OHP, testosterone, and ACTH. Clitoroplasty with vaginoplasty was performed at the age of 18 in the older sister. Using PCR/ACRS, we performed molecular analysis of the nine most common point CYP21A2 mutations in the patients and family members. The P30L/II72N genotype was observed in both sisters. They had inadequate metabolic control due to noncompliance until decision to conceive. IVF was performed three times in the older sister without success. Sufficient follicles were harvested and fertilized; however, the embryos were lost 3-5 days after implantations. The younger sister is preparing for IVF. She underwent follicle harvesting and the embryos were frozen awaiting appropriate hormonal balance for embryo transfer. The I172N mutation in the heterozygote state was observed in their other two sisters, whose fertility was unaffected.

CONCLUSIONS

Despite significant improvements over the last years in achieving fertility in female patients with SV CAH, it is highly dependent upon the severity of virilization and the metabolic control. The role of P30L mutation in infertility and unsuccessfully assisted reproduction remains to be elucidated.

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.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

Clinical, biochemical and genetic features with nonclassical 21-hydroxylase deficiency and final height

BACKGROUND

The clinical, laboratory, genetic properties and final height of a large cohort of patients with nonclassical 21-hydroxylase deficiency (NC21OHD) in Turkey were analyzed.

METHODS

This multicenter, nationwide web-based study collected data.

RESULTS

The mean age was 9.79±4.35 years (229 girls, 29 boys). The most common symptoms were premature pubarche (54.6%) and hirsutism (28.6%). The peak cortisol was found below 18 μg/dL in three (15.45%) patients. A mutation was detected in the CYP21A2 gene of 182 (87.5%) patients. The most common mutation was V281L. Final height in female patients who were diagnosed and treated before attaining final height or near final height was found to be shorter than the final height in female patients who were diagnosed after attaining final height or near final height.

CONCLUSIONS

The final height of the patients who were treated during childhood was found to be shorter than the final height of patients during the adolescent period.

Variations in the 3'UTR of the CYP21A2 Gene in Heterozygous Females with Hyperandrogenaemia

Heterozygosity for CYP21A2 mutations in females is possibly related to increased risk of developing clinical hyperandrogenism. The present study was designed to seek evidence on the phenotype-genotype correlation in female children, adolescents, and women with CYP21A2 mutations and variants in the 3'UTR region of the gene. Sixty-six patients out of the 169 were identified as carriers of CYP21A2 mutations. Higher values of stimulated 17 hydroxyprogesterone (17-OHP) levels were found in the carriers of the p.Val281Leu mutation compared to the carriers of other mutations (mean: 24.7 nmol/l versus 15.6 nmol/l). The haplotype of the ∗52C>T, ∗440C>T, and ∗443T>C in the 3'UTR was identical in all heterozygous patients with p.Val281Leu and the haplotype of the ∗12C>T and ∗52C>T was identical in all heterozygous patients with the p.Gln318∗. In conclusion, hyperandrogenaemic females are likely to bear heterozygous CYP21A2 mutations. Carriers of the mild p.Val281Leu mutation are at higher risk of developing hyperandrogenism than the carriers of more severe mutations. The identification of variants in the 3'UTR of CYP21A2 in combination with the heterozygous mutation may be associated with the mild form of nonclassic congenital adrenal hyperplasia and reveal the importance of analyzing the CYP21A2 untranslated regions for the appropriate management of this category of patients.

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

INTRODUCTION

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Molecular diagnosis of Chinese patients with 21-hydroxylase deficiency and analysis of genotype-phenotype correlations

Objective The spectrum of molecular defects in Chinese patients with 21-hydroxylase deficiency (21-OHD), and genotype-phenotype relationships are unknown. Methods We screened eight patients with non-classical (NC) 21-OHD and 35 with classical 21-OHD, and detected nine known mutations. Results The most frequent mutation among the 43 21-OHD cases was p.Ile172Asn (allele frequency, 36.0%), followed by c.290-13A/C > G (20.9%), Del (8.6%), p.Pro30Leu (7.0%), p.Gln318Ter (7.0%), p.Val281Leu (4.7%), p.Arg356Trp (2.3%), p.[Ile236Asn; Val237Glu; Met239Lys] (2.3%), and E3Δ8 bp (1.2%). The frequency spectrum of CYP21A2 mutations in the Chinese population was similar to that in the Japanese population, except that p.Val281Leu was identified in Chinese NC21-OHD patients at a frequency of 25.0%, whereas it was absent in Japanese patients. We found that genotype could predict phenotype in 88.3% of patients. Conclusion Some characteristics appear to be unique to the Chinese population, but genotype was strongly predictive of phenotype.

Molecular genetic analysis in 93 patients and 193 family members with classical congenital adrenal hyperplasia due to 21-hydroxylase deficiency in Croatia

Congenital adrenal hyperplasia owing to 21-hydroxylase deficiency is caused by mutation in the CYP21A2 gene. The frequency and spectrum of CYP21A2 mutations and genotype-phenotype correlations among different populations are variable. Aim of this study was to define mutation frequency and spectrum of CYP21A2 gene mutations in patients with classical 21-hydroxylase deficiency (21OHD) and their family members in Croatia and study genotype-phenotype correlation. Clinical features and mutations of CYP21A2 gene in 93 unrelated 21OHD patients and 193 family members were examined. In this cohort, 66 patients were affected with salt wasting (SW) form, and 27 were affected with simple virilizing (SV) form of the disease. Mutations were identified in both alleles (67% compound heterozygous and 33% homozygous) in 91 of 93 patients. Deletions and conversions were found in 18.8% and point mutations in 79.6% alleles. Mutations in 3 alleles (1.6%) remained unidentified (in one patient we found only one, while in other no mutations were found at all). The most common point mutations were Intron 2 splice mutation IVS2-13 A/C>G (35.5%) and p.R357W (16.7%). Genotypes were categorized into Groups 0, A, B and C according to the extent of enzyme impairment. Genotype-phenotype concordance was 100%, 85% and 75% for Groups 0, A and B, respectively. Since only classical 21OHD patients were studied, Group C comprised solely p.P31L mutation and had 73% patients with SV and 27% with SW phenotype. Intrafamilial phenotypic variability was found in two families. CYP21A2 genetic analysis in 193 family members showed that 126 parents were heterozygous carriers, 3 were newly discovered patients, 2 fathers were not biological parents, and mutations were not detected in 3. Among 59 siblings, 32 were heterozygous carriers, 15 carried normal alleles, and 12 were patients (4 newly diagnosed). Genotype-phenotype divergence observed in this study suggests caution in preconceptional counseling and prenatal diagnosis of CAH. High frequency of p.R357W mutation was found in Croatian patients with classical 21-OHD. Genotyping of family members discovered new patients and thus avoided pitfalls in genetic counseling when the parents were found to be affected.

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 spectrum of CYP21A2 mutations in Congenital Adrenal Hyperplasia in an Indian cohort

Congenital Adrenal Hyperplasia (CAH) is a common autosomal recessive disorder of the adrenal steroidogenic pathway. The most common form of CAH is due to mutations in CYP21A2 gene. The incidence of mutations in the CYP21A2 gene and the genotype-phenotype correlations vary among different populations. Therefore, the aim of the study was to establish the spectrum of mutations and to evaluate genotype-phenotype correlation in Indian CAH population. Molecular defects were investigated in 110 alleles (55 patients) in the present study. Notably, we identified disease causing mutations in 106 of 110 (96.4%) alleles whereas the frequency of undetectable mutations was 3.6%. The i2g mutation (20%) was found to be the most common in CAH patients. The second most common mutation was p.R356W (14.5%). p.I172N and 8-bp deletion in exon 3 accounted for 12.7% of the mutated alleles. In descending order, the other mutations present were p.Q318X (9%), E6 Cluster (5.4%), p.V281L (3.6%) and large gene deletion (3.6%). Additionally, p.P267L and frameshift mutation (L307fs/F306+T) were also detected in the Indian cohort with frequency of 1.8% and 5.4% respectively.rare mutation/rare mutations in the CYP21A2 gene were detected viz., p.D234D (NCBI accession number - KF812549), p.F306V (NCBI accession number - KF534754), p.P357P (NCBI accession number - KF692099) and p.H365N (NCBI accession number - KF447378). The genotypes of the patients were categorized into four groups null, A, B and C. Of note, correlation between genotype and phenotype is sufficiently strong, to be of clinical significance in the genetic counseling.

Molecular Analysis of CYP21A2 Gene Mutations among Iraqi Patients with Congenital Adrenal Hyperplasia

Congenital adrenal hyperplasia is a group of autosomal recessive disorders. The most frequent one is 21-hydroxylase deficiency. Analyzing CYP21A2 gene mutations was so far not reported in Iraq. This work aims to analyze the spectrum and frequency of CYP21A2 mutations among Iraqi CAH patients. Sixty-two children were recruited from the Pediatric Endocrine Consultation Clinic, Children Welfare Teaching Hospital, Baghdad, Iraq, from September 2014 till June 2015. Their ages ranged between one day and 15 years. They presented with salt wasting, simple virilization, or pseudoprecocious puberty. Cytogenetic study was performed for cases with ambiguous genitalia. Molecular analysis of CYP21A2 gene was done using the CAH StripAssay (ViennaLab Diagnostics) for detection of 11 point mutations and >50% of large gene deletions/conversions. Mutations were found in 42 (67.7%) patients; 31 (50%) patients were homozygotes, 9 (14.5%) were heterozygotes, and 2 (3.2%) were compound heterozygotes with 3 mutations, while 20 (32.3%) patients had none of the tested mutations. The most frequently detected mutations were large gene deletions/conversions found in 12 (19.4%) patients, followed by I2Splice and Q318X in 8 (12.9%) patients each, I172N in 5 (8.1%) patients, and V281L in 4 (6.5%) patients. Del 8 bp, P453S, and R483P were each found in one (1.6%) and complex alleles were found in 2 (3.2%). Four point mutations (P30L, Cluster E6, L307 frameshift, and R356W) were not identified in any patient. In conclusion, gene deletions/conversions and 7 point mutations were recorded in varying proportions, the former being the commonest, generally similar to what was reported in regional countries.

Molecular CYP21A2 diagnosis in 480 Brazilian patients with congenital adrenal hyperplasia before newborn screening introduction

BACKGROUND

Most congenital adrenal hyperplasia (CAH) patients carry CYP21A2 mutations derived from conversion events involving the pseudogene, and the remaining carry new mutations.

OBJECTIVE

To review causal mutations and genotype-phenotype correlation in 480 Brazilian patients.

METHODS

DNA was extracted from 158 salt-wasters (SWs), 116 simple virilizing (SV), and 206 nonclassical (NC) patients. Fourteen point mutations were screened by allele-specific PCR, large rearrangements by Southern blotting/MLPA, and sequencing was performed in those with incomplete genotype. The gene founder effect was analyzed by microsatellite studies. Patients were divided into six genotypes (Null; A: <2%; B: 3-7%; C: >20% of residual enzymatic activity (EA); D: unknown EA; E: incomplete genotype).

RESULTS

Targeted methodologies defined genotype in 87.6% of classical and in 80% of NC patients and the addition of sequencing in 100 and 83.5%, respectively. The most frequent mutations were p.V281L (26.6% of alleles), IVS2-13A/C>G (21.1%), and p.I172N (7.5%); seven rare mutations and one novel mutation (p.E351V) were identified. Gene founder effect was observed in all but one (p.W19X) mutation. Null, A, B, and C genotypes correlated with SW (88%), SW (70%), SV (98%), and NC forms (100%), respectively. In group D, the p.E351V mutation correlated with classical form and group E comprised exclusively NC-patients. ACTH-stimulated 17OHP level of 44.3ng/mL was the best cutoff to identify NC-patients carrying severe mutations.

CONCLUSIONS

We identified a good genotype-phenotype correlation in CAH, providing useful data regarding prediction of disease's severity; moreover, we suggest that ACTH-stimulated 17OHP levels could predict carrier status for severe mutations. Sequencing is essential to optimize molecular diagnosis in Brazilian CAH patients.

Molecular genetic study of congenital adrenal hyperplasia in Serbia: novel p.Leu129Pro and p.Ser165Pro CYP21A2 gene mutations

PURPOSE

Congenital adrenal hyperplasia (CAH) is an autosomal recessive disease characterized by impaired adrenal steroidogenesis and most often caused by CYP21A2 gene mutations. For the first time, we reported complete spectrum and frequency of CYP21A2 gene mutations in 61 unrelated patients with classical and non-classical CAH from Serbia.

METHODS

Direct DNA sequencing of whole CYP21A2 gene and polymerase chain reaction with sequence-specific primers for detection of CYP21A1P/CYP21A2 chimeras were combined.

RESULTS

We identified 18 different pathogenic alleles-two of them novel. Mutation detection rate was highest in patients with salt-wasting form of CAH (94.7%). The most prevalent mutation was intron 2 splice site mutation, c.290-13A/C>G (18.5%). Other mutation frequencies were: CYP21A1P/CYP21A2 chimeras (13%), p.P30L (13%), p.R356W (11.1%), p.G110fs (7.4%), p.Q318X (4.6%), p.V281L (4.6%), p.I172N (2.8%), p.L307fs (2.8%), p.P453S (1.9%), etc. Mainly, frequencies were similar to those in Slavic populations and bordering countries. However, we found 6.5% of alleles with multiple mutations, frequently including p.P453S. Effects of novel mutations, c.386T>C (p.Leu129Pro) and c.493T>C (p.Ser165Pro), were characterized in silico as deleterious. The effect of well-known mutations on Serbian patients' phenotype was as expected.

CONCLUSIONS

The first comprehensive molecular genetic study of Serbian CAH patients revealed two novel CYP21A2 mutations. This study will enable genetic counseling in our population and contribute to better understanding of molecular landscape of CAH in Europe.

High frequency of splice site mutation in 21-hydroxylase deficiency children

PURPOSE

Steroid 21-hydroxylase deficiency (21-OHD) is the common type of congenital adrenal hyperplasia (CAH) caused by defects in the CYP21A2 gene, as an autosomal recessive disease, genetic analysis has a prominent role in its diagnosis. Our objectives were to determine the prevalence of common mutations in a group of Egyptian patients with 21-OHD and their families using rapid methods, and also to detect the rate of deletion, duplication and conversions in CYP21A2 gene.

METHODS

Rapid detection methods were used: allele-specific PCR for c.293-13A>G (g.659A>G), c.518T>A (p.I172N) variants and c.332_339del (8-bp deletion in exon 3), and real-time, quantitative PCR assay was used to detect deletion in the CYP21A2 gene. 29 Egyptian patients, 38 family members, and 20 healthy controls were all included in the study.

RESULTS

The frequency of c.293-13A>G splice mutation was reported in 96.6 % cases, G allele had 2.5-folds higher risk to develop CAH than other alleles. The c.518T>A mutation was reported in 69 % cases, children carrying the mutant allele were 2.1 times more risk. The most frequent combined mutations detected were c.293-13A/C>G/c.518T>A in 58.6 % cases.

CONCLUSION

The genetic analysis of the splice site mutation c.293-13A>G and c.518T>A variant can be used as good biomarkers for early detection of cases and carriers in 21-OHD CAH Egyptian children, since the methods used have rapid turnaround time.

Genetic defects of the CYP21A2 gene in girls with premature adrenarche

OBJECTIVES

To seek evidence on the prevalence of CYP21A2 genetic defects and consequences in girls with premature adrenarche (PA).

METHODS

The study included 59 girls diagnosed with PA. Direct DNA sequencing and MLPA analysis were performed to identify mutations in CYP21A2 gene.

RESULTS

Twelve girls were diagnosed with non-classic congenital adrenal hyperplasia (NC-CAH) based on stimulated 17-hydroxyprogesterone (17-OHP) levels and the presence of two mutations in CYP21A2, 19 were heterozygotes. The most frequent mutations detected were the mild p.Val281Leu and p.Pro453Ser. Higher levels of mean stimulated 17-OHP were found in the carriers of the p.Val281Leu mutation. The detection rate for two CYP21A2 mutations was higher in girls with PA than in adult females with hyperandrogenemia in our studied population. A notable increased allelic frequency for the known p.Asn493Ser polymorphism was observed in the pool of the 28 girls with PA in whom no mutation was identified.

CONCLUSIONS

In girls with PA, the frequency of the underlying CYP21A2 genetic defects is similar to that observed in other populations. The carrier status is likely a contributing factor in the genotype-phenotype correlation in NC-CAH. However, polymorphisms and other genes may be implicated in the clinical manifestation of the disease.

The spectrum of clinical, hormonal and molecular findings in 280 individuals with nonclassical congenital adrenal hyperplasia caused by mutations of the CYP21A2 gene

BACKGROUND

Nonclassical congenital adrenal hyperplasia (NC-CAH) is caused by mutations of the CYP21A2 gene. The clinical manifestations and hormonal derangements of NC-CAH are quite variable.

OBJECTIVES

(i) To define the phenotype and its relation to genotype according to gender and age and (ii) to evaluate the validity of currently applied hormonal criteria for establishing the diagnosis of NC-CAH.

PATIENTS AND METHODS

The clinical, hormonal and molecular data of 280 subjects (235 female) with NC-CAH and a median age of 17·6 years were analysed. CYP21A2 genotyping was performed in all subjects.

RESULTS

The majority of females aged less than 8 years presented with premature pubarche (88·3%), while those older than 8 presented with a polycystic ovary-like phenotype (63·2%). A total of 7·7% of the females and 51·1% of the males were asymptomatic at the time of diagnosis. In the total group, 50·4% of the subjects were compound heterozygotes for one classical (C) and one nonclassical (NC) mutation, while 46% of the alleles studied carried the p.V281L mutation. Basal 17OHP values were below 6 nm (2 ng/ml) in 2·1% of the subjects with NC-CAH, but none had peak 17OHP values post-ACTH lower than 30 nm (10 ng/ml).

CONCLUSIONS

NC-CAH has a variable phenotype depending on the age, gender and the presence of a classical mutation. A peak cut-off value of 17OHP post-ACTH lower than 30 nm excludes the diagnosis of NC-CAH, whereas basal 17OHP <6 nm may represent a false-negative result. A significant number of patients harboured a classical mutation, a finding which requires genotyping of the partner for genetic counselling.

Hormonal disturbances due to severe and mild forms of congenital adrenal hyperplasia are already detectable in neonatal life

AIM

National screening programmes for congenital adrenal hyperplasia now include measuring several adrenal metabolites using highly sensitive liquid chromatography-tandem mass spectrometry. The aim of this study was to compare neonatal hormonal profiles - whole blood concentrations of 17α-hydroxyprogesterone, androstenedione, and cortisol - with genotypes in 21-hydroxylase deficiency.

METHODS

The study included 62 patients with congenital adrenal hyperplasia born between 1982 and 2012 and 61 random controls born in 1985 and 2005. Patients were grouped according to mutation-based predictions of enzyme impairment. Groups Null and A were salt-wasting (n = 35), Group B was simple virilising (n = 7) and Group C was nonclassic (n = 20). Dried blood spot samples were retrieved from the Danish Neonatal Screening Biobank.

RESULTS

All patients with molecular verified 21-hydroxylase deficiency had significantly higher concentrations of 17α-hydroxyprogesterone (p < 0.001), androstenedione (p < 0.001) and a higher ratio [(17α-hydroxyprogesterone + androstenedione)/cortisol, p < 0.05] than controls. Androstenedione showed a higher sensitivity (72%) than 17α-hydroxyprogesterone (12%) to correctly identify Groups B and C.

CONCLUSION

There were significant differences in neonatal hormonal profiles between all groups and controls. This confirms that hormonal disturbances are already detectable in both severe and mild forms of congenital adrenal hyperplasia in neonatal life.

Phenotypic variability of hyperandrogenemia in females heterozygous for CYP21A2 mutations

OBJECTIVES

The objective was to seek evidence on the prevalence and consequences of heterozygous CYP21A2 mutations in girls, adolescent, and adult females with clinical manifestation of androgen excess.

PATIENTS AND METHODS

The study included 64 girls diagnosed with premature adrenarche (PA) in childhood and 141 females with clinical hyperandrogenemia manifested in adolescence or adulthood. Direct DNA sequencing and multiplex ligation-dependent probe amplification analysis were used to identify mutations in the CYP21A2 gene.

RESULTS

(1) Thirty-four patients were diagnosed with nonclassical-congenital adrenal hyperplasia (NC-CAH) based on the 17-hydroxyprogesterone (17-OHP) levels and the presence of two mutations in CYP21A2 and therefore were excluded from the study, 66 were found to be heterozygotes and finally 105 had no identifiable mutations. The most frequent mutations among the carriers were the mild p.Val281 Leu and p.Qln318stop. Higher levels of mean stimulated 17-OHP were found in the carriers of the p.Val281 Leu. (2) A notable increased allelic frequency for the known p.Asn493 Ser polymorphism was observed in the pool of females with hyperandrogenemia in whom no mutation was identified. (3) In girls, who presented early with PA, 26.6% were diagnosed with NC-CAH and carried two mutations, 28.7% were identified as heterozygotes 43.7% had no identifiable genetic defect in the translated region of the CYP21A2 gene. On the contrary, in the group of 141 females with late onset hyperandrogenemia, the presence of 2 mutations was detected in 12%, 1 mutation in 33.4% and no mutation in 54.6%.

CONCLUSIONS

The carrier status for 21-OHD, may be an important factor in the variable phenotype of hyperandrogenism and may be a contributing factor for the early manifestation of the disease.

Direct Molecular Diagnosis of CYP21A2 Point Mutations in Macedonian and Serbian Patients with 21-Hydroxylase Deficiency

Background

Steroid 21-hydroxylase deficiency is present in 90–95% of all cases with congenital adrenal hyperplasia (CAH), an autosomal recessive disorder. It can present as the severe classical salt wasting (SW) or simple virilising (SV) form, or the milder, nonclassical form. Nine pseudogene-derived point mutations account for about 80% of all defects in the CYP21A2 gene coding the 21-hydroxylase enzyme.

Methods

We have studied nine CYP21A2 point mutations in 61 Macedonian and 24 Serbian patients with different clinical presentations of CAH, using the PCR/ACRS method.

Results

Six different mutations were detected in 71.3% of alleles of the Macedonian patients. The most prevalent mutation was IVS2. Mutations were detected in 85.4% of the SW, 83.4% SV and 47.7% LO alleles. In the Macedonian patients the most common genotype was IVS2/IVS2. Five different mutations were detected in 64.6% of alleles of the Serbian patients. The most prevalent was P30L. Mutations were present in 83.3% SW, 80% SV and 50% of the LO alleles. In the Serbian patients, the P30L/P30L genotype was the most frequent.

Conclusions

Specific CYP21A2 mutations are involved in different clinical forms of CAH. High frequency of P30L was found in both populations. Also, high prevalence of the mild P30L mutation was found in both the Macedonian and Serbian classical SV patients. Our findings support the role of the P30L mutation in pronounced virilisation. An unusual finding is the low frequency of V281L in the Macedonian non-classical patients and its absence in the ones from Serbia.

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

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

No evidence of an increase in early infant mortality from congenital adrenal hyperplasia in the absence of screening

OBJECTIVE

Congenital adrenal hyperplasia (CAH) is not currently included in the UK newborn screening programme. We investigated the hypothesis that, owing to non-specificity of symptoms, a proportion of males affected by salt-wasting (SW) CAH have died in infancy without being diagnosed.

DESIGN

Stored newborn screening blood spot samples were analysed for 17α-hydroxyprogesterone (17-OHP) in the following groups: Infants born in the North West of England, 1994 to 2006, who had died by 6 months age; (n=1198), a neonatal reference group (full-term n=100; preterm n=100) and a CAH positive control group. A newborn blood spot sample collected before diagnosis was available in 29/61 CAH patients recruited. SW CAH was present in 18/29 patients (16 males and 2 females). Samples from the deceased group with elevated 17-OHP were analysed for 8 common mutations in the 21-hydroxylase gene (CYP21A2).

SETTING

North West of England.

RESULTS

Grouped by gestational age, mean (maximum) blood spot 17-OHP in nmol/L was as follows. Deceased full-term n=279, 6 (107); deceased premature n=365, 28 (251); deceased unknown gestational age n=553, 13 (>394). In the SW positive control group, the lowest level of 17-OHP was 179 nmol/L and 14 had levels greater than the highest standard (>268 to >420 nmol/L). All samples from the deceased group with 17-OHP results >179 nmol/L (n=6) and a further 13 samples underwent mutation analysis. No mutations were identified.

CONCLUSIONS

Our findings do not support the hypothesis that, in our unscreened population, males affected by SW CAH are dying prior to diagnosis.

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.

Management of adolescents with congenital adrenal hyperplasia

The management of congenital adrenal hyperplasia involves suppression of adrenal androgen production, in addition to treatment of adrenal insufficiency. Management of adolescents with congenital adrenal hyperplasia is especially challenging because changes in the hormonal milieu during puberty can lead to inadequate suppression of adrenal androgens, psychosocial issues often affect adherence to medical therapy, and sexual function plays a major part in adolescence and young adulthood. For these reasons, treatment regimen reassessment is indicated during adolescence. Patients with non-classic congenital adrenal hyperplasia require reassessment regarding the need for glucocorticoid drug treatment. No clinical trials have compared various regimens for classic congenital adrenal hyperplasia in adults, thus therapy is individualised and based on the prevention of adverse outcomes. Extensive patient education is key during transition from paediatric care to adult care and should include education of females with classic congenital adrenal hyperplasia regarding their genital anatomy and surgical history. Common issues for these patients include urinary incontinence, vaginal stenosis, clitoral pain, and cosmetic concerns; for males with classic congenital adrenal hyperplasia, common issues include testicular adrenal rest tumours. Transition from paediatric to adult care is most successful when phased over many years. Education of health-care providers on how to successfully transition patients is greatly needed.

Mutational characterization of congenital adrenal hyperplasia due to 21-hydroxylase deficiency in Malaysia

BACKGROUND AND AIM

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21-OHD) is a common autosomal recessive disorder. Our objective was to identify the 21-hydroxylase active gene, CYP21A2 mutations in Malaysian 21-OHD patients using different techniques.

MATERIALS AND METHODS

Blood samples were obtained from 97 Malaysian 21-OHD patients, which included 40 siblings from 19 families. We used various techniques which include restriction enzyme digestion, Southern blot, multiple ligation-dependent probe amplification (MLPA) and sequencing to elucidate CYP21A2 mutations.

RESULTS

Homozygous and compound heterozygous mutations were identified in 95 of the 97 patients (98%). Deletions of CYP21A2 were found in 43 patients (44.3%). Deletions identified in CYP21A2 gene were the usual 30-kb deletion comprising 3'UTR CYP21A1P, C4B and 5'CYP21A2, complete deletion of CYP21A2 gene, deletion in exons 1-3, exons 1-6 and exons 1-8 of CYP21A2. The common mutations identified in CYP21A2 gene were deletion/conversion (22.6%), p.R356W (22%), IVS2-13A/C>G (21.3%), p.I172N (5.3%), p.Q318X (5.3%), and p.P30L (1.03%). This is the first report of the mutation frequency in CYP21A2 gene among the Malay ethnic group. Two novel mutations, c.Y97insT and p.L345P were identified in our patients. Our results show good phenotype-genotype correlation in most of the cases, although clinical variations were identified in some patients.

CONCLUSIONS

The study has found various mutations including deletions in CYP21A2 gene in Malaysian patients with 21-hydroxylase deficiency using the MLPA technique that is being widely used in present laboratory settings.

Reverse-hybridization assay for rapid detection of common CYP21A2 mutations in dried blood spots from newborns with elevated 17-OH progesterone

BACKGROUND

Congenital adrenal hyperplasia (CAH) is an autosomal recessive disorder most commonly caused by defects in the CYP21A2 gene. Neonatal CAH-screening based on 17-hydroxyprogesterone (17-OHP) measurements prevents life-threatening salt wasting conditions in newborns, but results in a considerable false-positive rate. Therefore, efficient second tier tests are required.

METHODS

We developed a reverse-hybridization test strip-based assay (CAH StripAssay) covering the most prevalent CYP21A2 point mutations/small insertions/deletions occurring in Middle European populations. Assay specificity was validated using plasmid clones, and wild-type and mutant reference DNAs. Its practicability was evaluated in 271 samples from patients with CAH, suspected CAH, and dried blood spots from screening-positive newborns.

RESULTS

All eleven point mutations and 51% of large deletions/conversions could be unambiguously identified when compared to reference methods (DNA sequencing, MLPA). After exclusion of rare mutations (6.4%) not covered by the StripAssay, the overall detection rate was 85%. Undetected heterozygous deletions/conversions caused a lack of information, but did not result in an incorrect prediction of phenotypes.

CONCLUSIONS

Our novel CAH StripAssay proved to be a fast (7h) and reliable method for detection of common CYP21A2 mutations. Implemented as a second-tier test in CAH newborn screening, it has the potential to significantly reduce recall rates.

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.

Steroid 21-hydroxylase gene mutational spectrum in 50 Tunisian patients: characterization of three novel polymorphisms

Congenital adrenal hyperplasia (CAH) is an autosomal recessive disease of steroid biosynthesis in humans. More than 90% of all CAH cases are caused by mutations of the 21-hydroxylase gene (CYP21A2), and approximately 75% of the defective CYP21A2 genes are generated through an intergenic recombination with the neighboring CYP21A1P pseudogene. In this study, the CYP21A2 gene was genotyped in 50 patients in Tunisia with the clinical diagnosis of 21-hydroxylase deficiency. CYP21A2 mutations were identified in 87% of the alleles. The most common point mutation in our population was the pseudogene specific variant p.Q318X (26%). Three novel single nucleotide polymorphism (SNP) loci were identified in the CYP21A2 gene which seems to be specific for the Tunisian population. The overall concordance between genotype and phenotype was 98%. With this study the molecular basis of CAH has been characterized, providing useful results for clinicians in terms of prediction of disease severity, genetic and prenatal counseling.

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.

A sequence variation in 3'UTR of CYP21A2 gene correlates with a mild form of congenital adrenal hyperplasia

BACKGROUND

Congenital adrenal hyperplasia (CAH) is mainly caused by the deficiency of the 21-hydroxylase enzyme coded by the CYP21A2 gene. However, some alleles in the non-classical form (NC-CAH) remain without identified mutations, suggesting the involvement of regulatory regions.

AIM

Our objective was to study an allele carrying the variant *13 G>A in the 3'UTR of the CYP21A2 gene identified in some patients with a mild form of NC-CAH in order to verify the possible implication of this variation with the phenotype observed.

SUBJECTS AND METHODS

Among all the subjects in whom the CYP21A2 gene was analyzed, 14 patients and 7 relatives heterozygous or homozygous for the *13 G>A substitution in 3'UTR were selected. Sequencing of DNA, genotyping, multiplex ligation-dependent probe amplification (MLPA), in vitro studies and bioinformatic analysis were performed.

RESULTS

The haplotype of the *13 G>A allele was identical in all the subjects with a monomodular structure composed by one C4A gene and one CYP21A2 gene without a second module with the CYP21A1P pseudogene. No other concomitant mutations were found in the region extending from 3 kb in the promoter and encompassing the polyadenylation signal. Both bioinformatic analysis and in vitro studies predicted an alteration of the RNA folding and expression, but no miRNA target sequences were found in this region.

CONCLUSIONS

The identification of a substitution in the 3'UTR of the gene associated with a mild form of NC-CAH suggests the importance of analyzing the CYP21A2 untranslated regions to better characterize and treat this subgroup of patients.

Steroid 21-hydroxylase gene mutational spectrum in 454 Argentinean patients: genotype-phenotype correlation in a large cohort of patients with congenital adrenal hyperplasia

OBJECTIVE

To report genotype-phenotype correlation in a large cohort of patients.

CONTEXT

Study of the CYP21A2 gene in 866 unrelated chromosomes of 21-hydroxylase deficiency in Argentinean patients with classic and nonclassic (NC) forms of congenital adrenal hyperplasia (CAH).

METHODS

Eleven most common mutations were analysed by allele-specific polymerase chain reaction, restriction fragment length polymorphism (RFLP) or southern blot analysis. Gene sequencing was performed when no mutation was detected in one allele or the genotype-phenotype correlation was lacking.

RESULTS

The 11-most-common-mutation screening allowed for the detection of 88·1% of affected alleles (80·3% in the NC and 95·2% in the classic forms). p.V281L, IVS2-13A/C>G (In2) and gene deletions and large gene conversions were the most prevalent mutations. In2 (35·2%) in salt wasting (SW), p.I172N (37·3%) in simple virilizing and p.V281L (54·1%) in NC CAH were the most prevalent mutations within the clinical forms. In 7/15 p.P30L mutation alleles, a chimeric CYP21A1P/CYP21A2 gene [PromCYP21A1P; p.P30L] was detected, while 6/15 represented a single-nucleotide substitution, and in 2/15 linkage with mutations, p.[P30L; V281L] and [p.P30L; IVS2-13A/C > G; p.Q318X] was found. In two SW patients, a novel nonsense mutation, p.Q41X, was observed. In three p.V281L mutation patients, the phenotype was more severe than predicted by genotype. Sequence analysis revealed an intronic alteration in the allele carrying the p.V281L mutation [IVS2 + 5G > A; p.V281L]. An aberrant splicing in this p.V281L mutated allele explains the clinical phenotype.

CONCLUSIONS

A high percentage of CYP21A2 affected alleles is detected by the 11-mutation screening study. Genotype-phenotype correlation was high, but when the phenotype is more severe than predicted by genotype, presence of two alterations in one allele should be ruled out.