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

A capillary electrophoresis-based assay for carrier screening of the hotspot mutations in the CYP21A2 gene

Molecular genetic analysis of the cytochrome P450 family 21 subfamily A member 2 (CYP21A2) gene is challenging owing to the highly homologous with its pseudogene. A reliable approach for the large-scale population screening of CYP21A2 is required. This study aimed to establish and evaluate a capillary electrophoresis-based assay for hotspot mutation carrier screening of the CYP21A2 gene. A total of 22 different variants in the CYP21A2 gene were detected by a capillary electrophoresis-based assay consisting of single nucleotide primer extension (SNaPshot) and high-throughput ligation-dependent probe amplification (HLPA) in the Chinese population, and the results were validated by alternative methods. Among the 5376 subjects, 1.51 % (81/5376) individuals were identified as CYP21A2 pathogenic variant carriers, with a carrier rate of 1/66. A total of 11 different variants were identified, of which c.293-13A/C > G (33.33 %) was the most common variant, followed by c.844C > T (19.75 %), c.518T > A (19.75 %), and Del/Con (16.05 %). There was a 100 % concordance between capillary electrophoresis and alternative method results. Furthermore, a total of 63 individuals (1.17 %, 63/5376) carried the c.955C > T (p. Q319∗) variant, among which 61 (61/63, 96.83 %) had a duplicated CYP21A2 gene and are therefore not carriers of a CYP21A2 allele. In conclusion, the capillary electrophoresis-based assay is an accurate and effective approach for genotyping the CYP21A2 gene and has the potential for the large-scale population screening of CYP21A2.

High carrier frequency of CYP21A2 gene mutations in Southern India - underscoring the need for genetic testing in Congenital Adrenal Hyperplasia

PURPOSE

Congenital Adrenal Hyperplasia (CAH) is one of the highly prevalent autosomal recessive endocrine disorders. The majority of CAH cases result from mutations in the CYP21A2 gene, leading to 21-hydroxylase deficiency. However, with the pseudogene-associated challenges in CYP21A2 gene analysis, routine genetic diagnostics and carrier screening in CAH are not a part of the first-tier investigations in a clinical setting. Furthermore, there is a lack of data on the carrier frequency for 21-OH deficiency. Therefore, this study is aimed at investigating the carrier frequency of common pseudogene derived CYP21A2 mutations in Southern India.

METHODS

Recently, a cost-effective Allele-specific PCR based genotyping for CYP21A2 hotspot mutations has been demonstrated to be a highly specific and sensitive assay at the authors' center. Leveraging this approach, a total of 1034 healthy individuals from South India underwent screening to identify the carrier frequency of nine hotspot mutations in the CYP21A2 gene.

RESULTS

In this study, it was observed that 9.76% of the subjects were carriers for one or more of the nine different CYP21A2 mutations. Among the carriers, the most common was the large 30 kb deletion, followed by II72N, E6 CLUS, and I2G mutations.

CONCLUSION

We have identified a high prevalence of CYP21A2 mutation carriers in Southern India. These findings emphasize the importance of implementing and expanding cost-effective genetic diagnostics and carrier screening throughout India. Such initiatives would play a crucial role in managing the disease burden, enabling early intervention, and establishing guidelines for CAH newborn genetic screening in the country. This study represents the first carrier screening data on CYP21A2 hotspot mutations from India and is the largest study conducted till date in this context.

Congenital Adrenal Hyperplasia - A Comprehensive Review of Genetic Studies on 21-Hydroxylase Deficiency from India

Congenital adrenal hyperplasia (CAH) comprises a heterogeneous group of autosomal recessive disorders impairing adrenal steroidogenesis. Most cases are caused by mutations in the CYP21A2 gene resulting in 21-hydroxylase (21-OH) deficiency (21-OHD). The genetics of 21-OH CAH is complexed by a highly homologous pseudogene CYP21A1P imposing several limitations in the molecular analysis. Therefore, genetic testing is still not a part of routine CAH diagnosis and is mainly dependent on 17-hydroxy progesterone (OHP) measurements. There are very few reports of CYP21A2 gene analysis from India and there is no comprehensive review available on genetic testing and the spectrum of CYP21A2 mutations from the country. This review focuses on the molecular aspects of 21-OHD and the genetic studies on CYP21A2 gene reported from India. The results of these studies insist the compelling need for large-scale CYP21A2 genetic testing and newborn screening (NBS) in India. With a high disease prevalence and consanguinity rates, robust and cost-effective genetic testing for 21-OH CAH would enable an accurate diagnosis in routine clinical practice. Whereas establishing affordable genotyping assays even in secondary care or resource-poor settings of the country can identify 90% of the mutations that are pseudogene derived, initiatives on reference laboratories for CAH across the nation with comprehensive genetic testing facilities will be beneficial in those requiring extended analysis of CYP21A2 gene. Further to this, incorporating genetic testing in NBS and carrier screening programmes will enable early diagnosis, better risk assessment and community-based management.

Characterization of the CYP21A2 Gene Mutations in Children with Classic Congenital Adrenal Hyperplasia

OBJECTIVE

To characterize the CYP21A2 gene mutations in children with classic congenital adrenal hyperplasia (CAH).

METHODS

A prospective, cross-sectional study was conducted on 24 children with classic CAH. Molecular characterization of the CYP21A2 gene was carried out by Sanger sequencing, multiplex ligation-dependent probe amplification (MLPA), or clinical exome sequencing. Another 21 previously mutation-proven CAH patients were also included and a combined result was drawn.

RESULTS

Out of 45 children, pathogenic variants in the CYP21A2 gene were identified in 43 patients (95.5%). Homozygous, probable compound heterozygous, and heterozygous variants were seen in 69%, 22%, and 18% of patients, respectively. The most common variant was c.293-13C/A>G (33%), followed by deletion/duplication (24%), and c.955C>T (p.Gln319Ter) (21%), similar to previous Indian studies. Allelic frequencies of c.332_339del and c.518 T>A (p.Ile173Asn) were 9% and 4%, respectively. Less common variants were c.923dupT (p.Leu308PhefsTer6), c.92C>T (p.Pro31Leu), c.1069C>T (p.Arg357Trp), c.1267G>C (p.Gly423Arg), and c.710_719delins (p.Ile237_Met240delinsAsnGluGluLys). A good genotype-phenotype correlation was observed; only p.Pro31Leu and p.Ile173Asn variants showed discordance. The diagnostic yield of Sanger sequencing alone, Sanger sequencing with MLPA, and clinical exome alone was 85%, 100%, and 100%, respectively.

CONCLUSIONS

All children, except two, diagnosed clinically as classic CAH, showed pathogenic variants in the CYP21A2 gene; the most common variant was c.293-13 C/A>G. The results suggest a broad mutation spectrum in the authors' single-center cohort of children with CAH. Clinical exome sequencing is the preferred stand-alone method for molecular diagnosis of CAH.

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.

Neonatal Screening for Congenital Adrenal Hyperplasia in Indian Newborns with Reflex Genetic Analysis of 21-Hydroxylase Deficiency

Congenital adrenal hyperplasia (CAH), screened for in neonates, is the second most common endocrinopathy after congenital hypothyroidism.Newborn screening for CAH due to CYP21A2 deficiency is performed by immunologic assay for 17-hydroxyprogesterone (17-OHP). The second-tier test for confirmation of diagnosis is carried out on recall venous blood sample from screen positives measuring 17-OHP, or other metabolites of steroid metabolism by liquid chromatography–tandem mass spectroscopy. However, as steroid metabolism is dynamic, it can affect these parameters even in the recall sample of a stressed neonate. Moreover, there is some time delay in recalling the neonate for repeat testing. Reflex genetic analysis of blood spot from the initial Guthrie cards of screen positive neonates, if used for confirmatory testing, can avoid this time delay as well as the effect of stress on steroid metabolism. In this study, we used Sanger sequencing and MLPA in a reflex manner for molecular genetic analysis to confirm CYP21A2-mediated CAH. Out of 220,000 newborns screened, 97 were positive on the initial biochemical screen, of which 54 were confirmed true positives with genetic reflex testing, giving incidence of CAH as 1:4074. Point mutations were more common than deletions, indicating that Sanger sequencing should be used ahead of MLPA for molecular diagnosis in India. Amongst the variants detected, the most common was I2G-Splice variant (44.5%), followed by c.955C>T (p.Gln319Ter) (21.2%); Del 8 bp and c.-113G>A were detected with frequencies of 20.3% and 20%, respectively. In conclusion, reflex genetic testing is an effective strategy for identifying true positives in CAH screening in neonates. This will obviate need for recall samples and also aid effective counselling and timely prenatal diagnosis in the future. In Indian newborns, as point mutations are more common than large deletions, Sanger sequencing should be the initial method of choice for genotyping, ahead of MLPA.

Molecular analysis and genotype-phenotype correlations in patients with classical congenital adrenal hyperplasia due to 21-hydroxylase deficiency from southern Poland - experience of a clinical center

PURPOSE

The prevalence of CYP21A2 gene variants and genotype-phenotype correlations are variable among populations. The aim of this study was to characterize CYP21A2 gene variants in adult patients with classical congenital adrenal hyperplasia (CCAH) from southern Poland and to analyze genotype-phenotype correlations.

MATERIALS/METHODS

A total of 48 patients (30 women and 18 men) with CCAH were included in the study. Patients were divided into two clinical subgroups, namely, salt-wasting (SW) - 38 patients and simple virilizing (SV) - 10 patients. A genetic analysis MLPA (multiplex ligation-dependent probe amplification) was performed in all of them. In dubious cases, the analysis was complemented by Sanger sequencing. Genotypes were classified into five groups (depending on the residual in vitro enzymatic activity), namely, null, A, B, C, and D, and correlated with the clinical picture.

RESULTS

Molecular defects were investigated and identified in 48 patients. The most common variant in the studied group was I2G, followed by whole or partial gene copy deletion, and I172N. One novel variant c.[878G>T] (p.Gly293Val) was found. In nine patients, a non-concordance between genotype and phenotype was observed. Genotype-phenotype correlations measured by positive predictive value (PPV) were as follows: 100% in group null, 90.5% in group A, and 66.7% in group B.

CONCLUSIONS

CYP21A2 variants in the studied cohort were similar to values previously reported in other countries of the region. There was a good correlation between genotype and phenotype in the null and A groups, the correlation being considerably lower in group B.

Allele-specific PCR and Next-generation sequencing based genetic screening for Congenital Adrenal Hyperplasia in India

Genetic screening of Congenital Adrenal Hyperplasia (CAH) is known to be challenging due to the complexities in CYP21A2 genotyping and has not been the first-tier diagnostic tool in routine clinical practice. Also, with the advent of massive parallel sequencing technology, there is a need for investigating its utility in screening extended panel of genes implicated in CAH. In this study, we have established and utilized an Allele-Specific Polymerase Chain Reaction (ASPCR) based approach for screening eight common mutations in CYP21A2 gene followed by targeted Next Generation Sequencing (NGS) of CYP21A2, CYP11B1, CYP17A1, POR, and CYP19A1 genes in 72 clinically diagnosed CAH subjects from India. Through these investigations, 88.7% of the subjects with 21 hydroxylase deficiency were positive for eight CYP21A2 mutations with ASPCR. The targeted NGS assay was sensitive to pick up all the mutations identified by ASPCR. Utilizing NGS in subjects negative for ASPCR, five study subjects were homozygous positive for other CYP21A2 variants: one with a novel c.1274G>T, three with c.1451G>C and one with c.143A>G variant. One subject was compound heterozygous for c.955C>T and c.1042G>A variants identified using ASPCR and NGS. One subject suspected for a Simple Virilizing (SV) 21 hydroxylase deficiency was positive for a CYP19A1:c.1142A>T variant. CYP11B1 variants (c.1201-1G>A, c.1200+1del, c.412C>T, c.1024C>T, c.1012dup, c.623G>A) were identified in all six subjects suspected for 11 beta-hydroxylase deficiency. The overall mutation positivity was 97.2%. Our results suggest that ASPCR followed by targeted NGS is a cost-effective and comprehensive strategy for screening common CYP21A2 mutations and the CAH panel of genes in a clinical setting.

The Spectrum of CYP21A2 Gene Mutations from 16 Families of Congenital Adrenal Hyperplasia: Genotype-Phenotype Correlation

AIM

Congenital adrenal hyperplasia (CAH) is an autosomal recessive disorder of the adrenal steroidogenic pathway. The most common form of CAH is due to 21-hydroxylase deficiency resulting from mutations in CYP21A2 gene. The present study aimed to identify CYP21A2 common gene mutations, phenotype correlation, and to analyze the segregation pattern in CAH patients, parents, and siblings.

MATERIALS AND METHODS

Sixteen families having at least one classic CAH child in each family, a total of 58 subjects were recruited. The presence of six most common gene mutations, namely, Intron 2 (c.293-13A/C>G), c.844G>T (p.Val282Leu), c.1019G>A (p.Arg340His), c.92C>T (p.Pro31Leu), c.955C>T (p.Gln319*), and c.518T>A (p.Ile173Asn) in CYP21A2 gene were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using specific primers.

RESULTS

Out of 16 classic CAH females analyzed, salt-wasting (SW) form was present in 12 (75%) and simple virilizing form in four (25%) children. Isolated clitoromegaly was the most common clinical presentation followed by ambiguous genitalia. The most common mutation observed in CAH patient population was Intron 2 (c.293-13A/C>G) (100%) followed by p.Pro31Leu (98%), p.Gln319* (93%), p.Val282Leu (91.4%), and p.Ile173Asn (19%). Although p.Arg340His mutation was not observed in this study. Interestingly, Intron 2 (c.293-13A/C>G) homozygous was observed in 31.3% of the entire study cohort and p.Ile173Asn mutation was found to be associated with SW form.

CONCLUSIONS

Our results suggested a high prevalence of CYP21A2 gene mutations among CAH patients and heterogeneous mutation spectrum in their families of south Indian cohort. The outcomes afford valuable evidence for premarital and prenatal screening as well as planning suitable programs to prevent the development of CAH in Indian population.

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

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

Clinical application of a novel next generation sequencing assay for CYP21A2 gene in 310 cases of 21- hydroxylase congenital adrenal hyperplasia from India

PURPOSE

Accurate diagnosis is required for management of Congenital adrenal hyperplasia (CAH). The conventional method for detection of mutations in the CYP21A2 gene is targeted capillary sequencing which is labor intensive and has limited multiplexing capability. Next generation sequencing (NGS) provides data with high sequence coverage and depth. Our objective was to develop an accurate NGS-based assay to characterize the mutation spectrum in CYP21A2 gene in Indian patients suspected to have 21-OH CAH.

METHODS

Cases with 21-OH CAH from 12 endocrine units across India were studied. DNA was extracted from proband's and parent's(subset) blood. Locus-specific long-range PCR and gel electrophoresis of amplicons was followed by NGS where no visible 30 kb homozygous/whole gene deletion was observed. Orthogonal confirmation was performed by capillary sequencing (ABI 3500) and Multiplex Ligation-dependent Probe Amplification (MLPA, MRC-Holland). PCR products were purified and individual libraries were pooled and sequenced (Illumina).

RESULTS

Of the 310 CAH cases, biallelic mutations (pathogenic/ likely pathogenic variants involving both CYP21A2 gene copies) were detected in 256 (82.6%), heterozygous mutations in 13 (4.2 %), and none in 41 (13.2%). Most common mutation was c.293-13A/C>G (29.03%), followed by 30 kb deletion (18.24%). Thirty samples tested orthogonally (by capillary sequencing or MLPA) showed 100% concordance with NGS assay. Nine novel variants were identified.

CONCLUSIONS

We have developed and validated a comprehensive NGS-based assay for detection of variants in CYP21A2 gene in patients with 21-OH CAH. We describe CYP21A2 mutation spectrum and novel variants in a large cohort of Indian patients with CAH.

The spectrum of CYP21A2 gene mutations in patients with classic salt wasting form of 2l-hydroxylase deficiency in a Chinese cohort

Background

21‐Hydroxylase deficiency (21‐OHD) caused by the CYP21A2 gene mutations is the most common form of congenital adrenal hyperplasia. It is an autosomal recessive disorder that results in defective synthesis of cortisol and aldosterone. The incidences of various CYP21A2 gene mutations and the genotype–phenotype correlations vary among different populations.

Materials and Methods

The clinical and molecular data of 22 patients were analyzed in this study. All patients were recruited from the neonatal intensive care unit. Locus‐specific polymerase chain reaction and Sanger sequencing were applied to identify gene micro‐conversions, and multiplex ligation‐dependent probe amplification was used to detect large fragment deletions/conversions. Then, the genotypes were categorized in to Null, A, B, C, and D groups to analyze the relationships between genotypes and phenotypes.

Results

All 22 patients were classified into classic salt wasting form of 21‐OHD. Molecular defects were detected in 44 alleles (100%). Micro‐conversion mutation IVS2‐13A/C>G (70.5%) is most common in our cohort, followed by large gene deletions and conversions (22.7%). The other mutations present were p.R357 W (4.5%) and E6 Cluster (2.3%). Genotypes of 22 patients (100%) were consistent with the predictive phenotypes.

Conclusion

In this study, we identified the mutation spectrum of CYP21A2 gene in Chinese patients, especially the younger age cohort in pediatrics. Micro‐conversions were the most popular mutations. Moreover, the genotypes and phenotypes were well correlated in this cohort of salt wasting 21‐OHD recruited from neonatal intensive care unit.

We identified the mutation spectrum of CYP21A2 gene in Chinese patients, especially the younger age cohort admitted in NICU. The genotypes and phenotypes in 21‐OHD were well correlated.

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.

Data on the functional consequences of the mutations identified in 21-Hydroxylase deficient CAH patients

This article presents the data set regarding the functional characterization of mutations in CYP21A2 gene in CAH patients as described in “Functional characterization and molecular modeling of the mutations in CYP21A2 gene from patients with Congenital Adrenal Hyperplasia (Khajuria et al., 2018) [1]. This data set features about the identification of mutations and their functional characterization by bioinformatic tools (mutation severity prediction softwares). Molecular modeling enabled us to locate the site of the amino-acid residues in 3-Dimensional model of 21-Hydroxylase protein which were mutated in patients.

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

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

Disorders of sex development: a study of 194 cases

OBJECTIVE

To study the clinical profile and the management of patients with disorders of sex development (DSD).

DESIGN AND SETTING

Retrospective study from a tertiary care hospital of North India.

METHODS AND PATIENTS

One hundred ninety-four patients of DSD registered in the Endocrine clinic of Postgraduate Institute of Medical Education and Research, Chandigarh between 1995 and 2014 were included.

RESULTS

One hundred and two patients (52.5%) had 46,XY DSD and seventy-four patients (38.1%) had 46,XX DSD. Sex chromosome DSD was identified in seven (3.6%) patients. Of 102 patients with 46,XY DSD, 32 (31.4%) had androgen insensitivity syndrome and 26 (25.5%) had androgen biosynthetic defect. Of the 74 patients with 46,XX DSD, 52 (70.27%) had congenital adrenal hyperplasia (CAH) and eight (10.8%) had ovotesticular DSD. Five patients with sex chromosome DSD had mixed gonadal dysgenesis. Excluding CAH, majority of the patients (90%) presented in the post-pubertal period. One-fourth of the patients with simple virilising CAH were reared as males because of strong male gender identity and behaviour and firm insistence by the parents. Corrective surgeries were performed in twenty patients (20%) of 46,XY DSD without hormonal evaluation prior to the presentation.

CONCLUSION

Congenital adrenal hyperplasia is the most common DSD in the present series. Most common XY DSD is androgen insensitivity syndrome, while CAH is the most common XX DSD. Delayed diagnosis is a common feature, and corrective surgeries are performed without seeking a definite diagnosis.

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.

Data on the 21-Hydroxylase deficient CAH patients and the identification of known/novel mutations in CYP21A2 gene

This article presents the dataset regarding spectrum of mutations in 21-Hydroxylase deficient CAH patients as described in “The spectrum of CYP21A2 mutations in Congenital Adrenal Hyperplasia in an Indian cohort” (R. Khajuria, R. Walia, A. Bhansali, R. Prasad, 2017) [1]. This dataset features about the CAH patients in the cohort, their classification into subtypes and finally screening the exon–intron boundaries of 21-Hydroxylase gene (CYP21A2) to detect common mutations, novel mutations along polymorphisms in the CYP21A2 gene. The specified large set of primers and the parameters for the mutation detection allow the identification and molecular characterization of CYP21A2 gene in the CAH patients.