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Pignatelli D, Carvalho BL, Palmeiro A, Barros A, Guerreiro SG, Macut D. The Complexities in Genotyping of Congenital Adrenal Hyperplasia: 21-Hydroxylase Deficiency. Front Endocrinol (Lausanne) 2019; 10:432. [PMID: 31333583 PMCID: PMC6620563 DOI: 10.3389/fendo.2019.00432] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 06/17/2019] [Indexed: 12/13/2022] Open
Abstract
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.
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Affiliation(s)
- Duarte Pignatelli
- Hospital S. João, Porto, Portugal
- Department of Biomedicine, Faculty of Medicine of Porto, Porto, Portugal
- IPATIMUP/I3S Research Institute, University of Porto, Porto, Portugal
- *Correspondence: Duarte Pignatelli
| | - Berta L. Carvalho
- Genetics, Department of Pathology, Faculty of Medicine, University of Porto, Porto, Portugal
- I3S Research Institute, University of Porto, Porto, Portugal
| | | | - Alberto Barros
- Genetics, Department of Pathology, Faculty of Medicine, University of Porto, Porto, Portugal
- I3S Research Institute, University of Porto, Porto, Portugal
| | - Susana G. Guerreiro
- Department of Biomedicine, Faculty of Medicine of Porto, Porto, Portugal
- IPATIMUP/I3S Research Institute, University of Porto, Porto, Portugal
| | - Djuro Macut
- Clinic of Endocrinology, Diabetes and Metabolic Diseases, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
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Nageshwari R, Dhivakar M, Balakrishnan K, Selvan SA, Kumaravel V. Common CYP21A2 Gene Mutations in South Indian Congenital Adrenal Hyperplasia Patients. INT J HUM GENET 2017. [DOI: 10.1080/09723757.2017.1383647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- R. Nageshwari
- Alpha Hospital and Research Centre, Madurai, Tamil Nadu, India
| | - M. Dhivakar
- Madurai Kamaraj University, Madurai, Tamil Nadu, India
| | | | | | - V. Kumaravel
- Alpha Hospital and Research Centre, Madurai, Tamil Nadu, India
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Marumudi E, Sharma A, Kulshreshtha B, Khadgawat R, Khurana ML, Ammini AC. Molecular genetic analysis of CYP21A2 gene in patients with congenital adrenal hyperplasia. Indian J Endocrinol Metab 2012; 16:384-388. [PMID: 22629504 PMCID: PMC3354845 DOI: 10.4103/2230-8210.95679] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
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.
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Affiliation(s)
- Eunice Marumudi
- Department of Endocrinology and Metabolism, and Anatomy, All India Institute of Medical Sciences, New Delhi, India
| | - Arundhati Sharma
- Department of Endocrinology and Metabolism, and Anatomy, All India Institute of Medical Sciences, New Delhi, India
| | - Bindu Kulshreshtha
- Department of Endocrinology and Metabolism, and Anatomy, All India Institute of Medical Sciences, New Delhi, India
| | - Rajesh Khadgawat
- Department of Endocrinology and Metabolism, and Anatomy, All India Institute of Medical Sciences, New Delhi, India
| | - Madan L. Khurana
- Department of Endocrinology and Metabolism, and Anatomy, All India Institute of Medical Sciences, New Delhi, India
| | - Ariachery C. Ammini
- Department of Endocrinology and Metabolism, and Anatomy, All India Institute of Medical Sciences, New Delhi, India
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Mizukami H, Hamamatsu A, Mori S, Hara S, Kuroda M, Nagai T, Fukunaga T. Autopsy and genetic diagnosis of 21-hydroxylase deficiency with bilateral testicular tumors in a case under no medication for over one year. Forensic Sci Int 2011; 206:e71-5. [PMID: 20951518 DOI: 10.1016/j.forsciint.2010.09.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Revised: 09/15/2010] [Accepted: 09/17/2010] [Indexed: 11/18/2022]
Abstract
The autopsy findings of an adult patient with 21-hydroxylase deficiency are presented. Genetic analysis of the 21-hydroxylase gene (CYP21A2) was performed for accurate diagnosis of congenital adrenal hyperplasia (CAH), and bilateral testicular tumors were characterized. We report a 29-year-old Japanese man who was diagnosed with CAH (21-hydroxylase deficiency) in infancy and had continued steroid therapy until the age of 28. However, for more than one year, he had not been treated for CAH and was found dead. In the medico-legal autopsy findings, both adrenal glands were enlarged, and hypertrophy of adrenal cortices and bilateral testicular tumors positive for melan-A were observed. Genomic DNA was prepared from cervical lymph nodes collected during autopsy, and CYP21A2 was PCR amplified and sequenced directly using newly designed primers. From the morphological findings, the bilateral testicular tumors were considered to be adrenogenital syndrome (TTAGS). Through the whole sequence of CYP21A2, the intron 2 splice mutation (656)A to (656)G was found. TTAGS were thought to be adrenal rests enlarged by ACTH stimulus. From the autopsy findings and the result of genetic analysis, he was diagnosed with the salt-wasting form of 21-hydroxylase deficiency and his cause of death was presumed to be heart failure based on abnormal electrolytes.
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Affiliation(s)
- Hajime Mizukami
- Department of Forensic Medicine, Tokyo Medical University, Shinjyuku 6-1-1, Shinjyuku-ku, Tokyo 160-8402, Japan.
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Kleinle S, Lang R, Fischer GF, Vierhapper H, Waldhauser F, Födinger M, Baumgartner-Parzer SM. Duplications of the functional CYP21A2 gene are primarily restricted to Q318X alleles: evidence for a founder effect. J Clin Endocrinol Metab 2009; 94:3954-8. [PMID: 19773403 DOI: 10.1210/jc.2009-0487] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Rare haplotypes with Q318X mutations and duplicated CYP21A2 genes have been reported to occur in different populations to a varying extent. Discrimination between a normal (Q318X mutation on one of the duplicated CYP21A2 genes) and a congenital adrenal hyperplasia (CAH, Q318X mutation without duplicated functional gene) allele is of importance, particularly for prenatal diagnosis and the respective genetic counseling. Although methods to differentiate between such alleles have been published only recently, it remains unclear with which frequency Q318X mutations are associated with duplicated CYP21A2 genes and whether these haplotypes have a common ancestry. SUBJECTS AND METHODS Human leukocyte antigen (HLA) typing has been performed in 38 unrelated individuals and in 11 family members detected to carry a Q318X mutation in the course of CYP21 genotyping using sequence, multiplex ligation-dependent probe amplification, and Southern blot analyses. RESULTS The majority (n = 32, 84.2%) of the 38 unrelated individuals carrying the Q318X mutation had the trimodular RCCX haplotype, carrying the Q318X mutation on a duplicated CYP21A2 gene. Twenty-two individuals of these 32 (68.8%) were of the rare HLA-B*50-Cw*06 haplotype, suggesting a common ancestry of this haplotype. In five (13.2%) of the 38 subjects, the Q318X mutation was not associated with a duplicated CYP21A2 gene and thus represents a CAH allele. None of these five patients had the above mentioned HLA haplotype. CONCLUSION The majority of individuals in whom Q318X mutations are detected carry a duplicated functional CYP21A2 gene and the rare HLA-B*50-Cw*06 haplotype.
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Affiliation(s)
- S Kleinle
- Department of Internal Medicine III, Division of Clinical Endocrinology and Metabolism, Medical University of Vienna, A-1090 Vienna, Austria
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Imamine R, Arima H, Kusakabe M, Umeda H, Sato I, Homma K, Usui T, Oiso Y. Genetic analysis of two Japanese patients with non-classical 21-hydroxylase deficiency. Intern Med 2009; 48:705-9. [PMID: 19420818 DOI: 10.2169/internalmedicine.48.1894] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We report two Japanese women with androgen excess symptoms. Analyses of 21-hydroxylase gene demonstrated that a 24-year-old Japanese woman had a homozygous mutation of IVS2-13 A/C>G, while a 25-year-old Japanese woman had a compound heterozygous mutation of I172N and E245del1nt, a novel mutation which would result in completely nonfunctional enzyme due to a frame shift. As IVS2-13 A/C>G and I172N have been classified as mutations leading to severe impairment in enzyme activity, this study not only clarified a novel mutation causing 21-hydroxylase deficiency, but also demonstrated that genotype and phenotype do not correlate well in these cases.
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Affiliation(s)
- Rui Imamine
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine
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Carvalho TAAD, Souza ICND, Yoshioka FKN, Caldato MCF, Torres NN, Garcia LS, Guerreiro JF. CYP21 gene mutations in Brazilian patients with 21-hydroxylase deficiency from the Amazon region. Genet Mol Biol 2008. [DOI: 10.1590/s1415-47572008000400004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Keen-Kim D, Redman JB, Alanes RU, Eachus MM, Wilson RC, New MI, Nakamoto JM, Fenwick RG. Validation and clinical application of a locus-specific polymerase chain reaction- and minisequencing-based assay for congenital adrenal hyperplasia (21-hydroxylase deficiency). J Mol Diagn 2005; 7:236-46. [PMID: 15858147 PMCID: PMC1867523 DOI: 10.1016/s1525-1578(10)60550-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/20/2004] [Indexed: 11/21/2022] Open
Abstract
Congenital adrenal hyperplasia is an autosomal recessive disorder caused by defective adrenal steroid biosynthesis, resulting in reduced glucocorticoid and increased androgen production. The majority of cases are due to inactivation of the 21-hydroxylase gene (CYP21A2), most commonly caused by genomic rearrangements with the adjacent, highly homologous pseudogene CYP21A. The most common deletions and gene conversion events have been defined and are typically detected by Southern hybridization detection of CYP21 rearrangements and/or polymerase chain reaction (PCR). However, Southern hybridization is laborious, and allele-specific PCR results may be difficult to interpret. We have therefore developed a locus-specific, PCR-based, minisequencing method for detecting the 12 most common CYP21A2 mutations. We validated the assay using a panel of 20 previously genotyped samples obtained from individuals who collectively have a broad spectrum of mutations causing 21-hydroxylase deficiency. We also used 19 control samples having no CYP21 mutations. All validation samples were correctly typed, and we identified haplotypes that may be useful for clinical diagnosis. Results from 102 clinical samples demonstrate that this assay is a rapid, reliable, and robust method for locus-specific identification of mutations and is suitable for routine clinical use and prenatal diagnosis.
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Affiliation(s)
- Dianne Keen-Kim
- Department of Molecular Endocrinology, Quest Diagnostics Nichols Institute, 33608 Ortega Highway, San Juan Capistrano, CA 92690-6130, USA
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Mao R, Nelson L, Kates R, Miller CE, Donaldson DL, Tang W, Ward K. Prenatal diagnosis of 21-hydroxylase deficiency caused by gene conversion and rearrangements: pitfalls and molecular diagnostic solutions. Prenat Diagn 2002; 22:1171-6. [PMID: 12478627 DOI: 10.1002/pd.467] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVES The present paper reports the prenatal diagnosis of congenital adrenal hyperplasia (CAH) in two cases of 21-hydroxylase deficiency. DNA diagnostic errors can be caused by the presence of the highly homologous 21-hydroxylase pseudogene, CYP21P, adjacent to the functional gene, CYP21. The present paper details how complex gene conversions and rearrangements between the CYP21 and CYP21P pose unique complications for prenatal diagnosis. METHODS Analysis of eight common mutations in the 21-hydroxylase gene as well as deletion of the entire gene is accomplished using polymerase chin reaction (PCR) followed by amplified created restriction site (ACRS) or allele-specific oligohybridization (ASO) and Southern blot followed by hybridization to a CYP21-specific probe. Linkage analysis was performed using microsatellite markers flanking the CYP21 gene. RESULTS The direct mutation detection assay indicated a complicated gene conversion and rearrangement in the probands of both families. Interpretation of these rearrangements made it difficult to determine whether or not the fetuses would be affected with CAH. Linkage studies revealed that each fetus had inherited both parental disease chromosomes and was therefore predicted to be affected with CAH. CONCLUSION As observed in the two reported cases, direct DNA analysis may provide limited information due to gene conversion or rearrangement between the CYP21 and CYP21P genes. These cases suggest that direct mutation detection should be supported by linkage analysis, whenever possible, to provide more comprehensive information for the family.
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Affiliation(s)
- Rong Mao
- DNA Diagnostic Laboratory, University of Utah School of Medicine, Salt Lake City, UT 84108, USA.
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10
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Speiser PW. Molecular diagnosis of CYP21 mutations in congenital adrenal hyperplasia: implications for genetic counseling. AMERICAN JOURNAL OF PHARMACOGENOMICS : GENOMICS-RELATED RESEARCH IN DRUG DEVELOPMENT AND CLINICAL PRACTICE 2002; 1:101-10. [PMID: 12174671 DOI: 10.2165/00129785-200101020-00003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Congenital adrenal hyperplasia (CAH) is an inherited disorder of steroid biosynthesis most often attributable to mutations in CYP21 (also termed CYP21A2) encoding the active steroid 21-hydroxylase enzyme. This review focuses on clinical and genetic aspects of CAH, and updates the reader on current methodology and applications for molecular genetic diagnosis. Genotyping patients with CAH has revealed > 50 mutations within CYP21, yet only 10 mutations account for approximately 95% of affected alleles. Many CYP21 mutations are gene conversions arising via transfer of gene sequences between the non-functional CYP21 pseudogene and CYP21. Phenotype is generally well-correlated with genotype. Historically, CAH has been divided into 3 types of disease: classic salt-wasting, classic simple virilizing (non-salt-wasting), and nonclassic. Recent findings support the notion that rather than discrete phenotypic categories, CAH is better represented as a continuum of phenotypes, from severe to mild. Molecular genetic diagnosis is most effectively employed now in prenatal diagnosis of classic CAH. As newborn screening for CAH becomes more widespread, genotyping may be implemented to resolve diagnostic difficulties encountered with hormonal testing. As automated methods of DNA diagnosis such as microarrays or gene chips are refined, it is likely that genetic screening will become less expensive and more readily available. The clinician should be aware of the potential for both false negatives and false positives with PCR-based gene screening. In short, whereas molecular genetic diagnosis is a valuable tool, it cannot replace clinical acumen and hormonal assays.
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Caulfield MP, Lynn T, Gottschalk ME, Jones KL, Taylor NF, Malunowicz EM, Shackleton CHL, Reitz RE, Fisher DA. The diagnosis of congenital adrenal hyperplasia in the newborn by gas chromatography/mass spectrometry analysis of random urine specimens. J Clin Endocrinol Metab 2002; 87:3682-90. [PMID: 12161496 DOI: 10.1210/jcem.87.8.8712] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Definitive neonatal diagnosis of congenital adrenal hyperplasia (CAH) is frequently complicated by normal 17-hydroxyprogesterone levels in 21-hydroxylase-deficient patients, residual maternal steroids, and other interfering substances in neonatal blood. In an effort to improve the diagnosis, we developed a gas chromatography/mass spectrometry method for simultaneous measurement of 15 urinary steroid metabolites as early as the first day of life. Furthermore, we developed 11 precursor/product ratios that diagnose and clearly differentiate the four enzymatic deficiencies that cause CAH. Random urine samples from 31 neonatal 21-hydroxylase-deficient patients and 59 age-matched normal newborns were used in the development. Additionally, samples from two 11 beta-hydroxylase-deficient patients and one patient each for 17 alpha-hydroxylase and 3 beta-hydroxysteroid dehydrogenase deficiencies were used. The throughput for one bench-top gas chromatography/mass spectrometry instrument is 20 samples per day. Thus, this method affords an accurate, rapid, noninvasive means for the differential diagnosis of CAH in the newborn period without the need for invasive testing and ACTH stimulation.
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Affiliation(s)
- Michael P Caulfield
- Quest Diagnostics' Nichols Institute, San Juan Capistrano, California 92690, USA
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12
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Krone N, Braun A, Weinert S, Peter M, Roscher AA, Partsch CJ, Sippell WG. Multiplex Minisequencing of the 21-Hydroxylase Gene as a Rapid Strategy to Confirm Congenital Adrenal Hyperplasia. Clin Chem 2002. [DOI: 10.1093/clinchem/48.6.818] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Background: Congenital adrenal hyperplasia (CAH) is a frequent autosomal recessive disease, with a wide range of clinical manifestations, most commonly attributable to mutations in the 21-hydroxylase gene (CYP21). Large gene deletions, large gene conversions, a small 8-basepair deletion, and eight point mutations in CYP21 account for ∼95% of all enzyme deficiencies. We developed a new strategy for a rapid CYP21 analysis.
Methods: DNA samples from 40 CAH patients previously genotyped by direct DNA sequencing were reanalyzed by allele-specific amplification of the functional CYP21 gene followed by a multiplex minisequencing reaction using 13 primers. In addition, a second PCR that amplified a part of exon 3 was used to demonstrate the presence or absence of at least one functional gene.
Results: The assay detected the P453S mutation and nine of the most common mutations (P30L, intron 2 splice, Δ8bp, I172N, exon 6 cluster, V281L, F306+t, Q318X, and R356W) caused by microconversions from the CYP21P pseudogene. The concordance was 100% for detecting these mutations, including gene deletions and large gene conversions. The 40 patient DNA samples were analyzed in 1.5 working days by one technician (actual hands-on time, 3.5 h). The material cost for analyzing one sample was approximately €10.00 (US $9.00).
Conclusions: This novel mutation screening strategy rapidly detects 90–95% of all mutations associated with CAH and appears applicable as a tool for confirmation of increased 17-hydroxyprogesterone found in neonatal CAH screening.
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Affiliation(s)
- Nils Krone
- Laboratory of Molecular Endocrinology, Division of Pediatric Endocrinology, Department of Pediatrics, Universitätsklinikum Kiel, Schwanenweg 20, D-24105 Kiel, Germany
| | - Andreas Braun
- Sequenom Inc., 3595 John Hopkins Court, San Diego, CA 92121-1331
| | - Stefanie Weinert
- Laboratory of Molecular Endocrinology, Division of Pediatric Endocrinology, Department of Pediatrics, Universitätsklinikum Kiel, Schwanenweg 20, D-24105 Kiel, Germany
| | - Michael Peter
- Laboratory of Molecular Endocrinology, Division of Pediatric Endocrinology, Department of Pediatrics, Universitätsklinikum Kiel, Schwanenweg 20, D-24105 Kiel, Germany
| | - Adelbert A Roscher
- Department of Clinical Chemistry, Metabolics and Molecular Genetics, University Children’s Hospital, Ludwig-Maximilians-Universität, München, Lindwurmstrasse 4, D-80337 Munich, Germany
| | - Carl-Joachim Partsch
- Laboratory of Molecular Endocrinology, Division of Pediatric Endocrinology, Department of Pediatrics, Universitätsklinikum Kiel, Schwanenweg 20, D-24105 Kiel, Germany
| | - Wolfgang G Sippell
- Laboratory of Molecular Endocrinology, Division of Pediatric Endocrinology, Department of Pediatrics, Universitätsklinikum Kiel, Schwanenweg 20, D-24105 Kiel, Germany
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Affiliation(s)
- C E Keegan
- Department of Pediatrics, University of Michigan, Ann Arbor 48109-0602, USA
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14
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Abstract
More than 90% of cases of congenital adrenal hyperplasia (CAH, the inherited inability to synthesize cortisol) are caused by 21-hydroxylase deficiency. Females with severe, classic 21-hydroxylase deficiency are exposed to excess androgens prenatally and are born with virilized external genitalia. Most patients cannot synthesize sufficient aldosterone to maintain sodium balance and may develop potentially fatal "salt wasting" crises if not treated. The disease is caused by mutations in the CYP21 gene encoding the steroid 21-hydroxylase enzyme. More than 90% of these mutations result from intergenic recombinations between CYP21 and the closely linked CYP21P pseudogene. Approximately 20% are gene deletions due to unequal crossing over during meiosis, whereas the remainder are gene conversions--transfers to CYP21 of deleterious mutations normally present in CYP21P. The degree to which each mutation compromises enzymatic activity is strongly correlated with the clinical severity of the disease in patients carrying it. Prenatal diagnosis by direct mutation detection permits prenatal treatment of affected females to minimize genital virilization. Neonatal screening by hormonal methods identifies affected children before salt wasting crises develop, reducing mortality from this condition. Glucocorticoid and mineralocorticoid replacement are the mainstays of treatment, but more rational dosing and additional therapies are being developed.
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Affiliation(s)
- P C White
- Division of Pediatric Endocrinology, University of Texas Southwestern Medical Center, Dallas 75390-9063, USA.
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Killeen AA, Jiddou RR, Sane KS. Characterization of frequent polymorphisms in intron 2 of CYP21: application to analysis of segregation of CYP21 alleles. Clin Chem 1998. [DOI: 10.1093/clinchem/44.12.2410] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
The gene encoding adrenal steroid 21-hydroxylase, CYP21, is located in the MHC class III region. Most cases of congenital adrenal hyperplasia (CAH) are caused by mutations in this gene, and most mutations appear to arise from gene conversion-like events involving the transfer of deleterious sequences from the pseudogene, CYP21P, which is located within 30 kb of CYP21. Approximately 20–30% of mutations are caused by deletions of CYP21. The second intron of CYP21 is polymorphic, and several base substitutions that include nt395, nt453, and nt601 have been reported; however, the frequencies of these polymorphisms are unknown. Using a combination of cleavase fragment length polymorphism analysis and direct sequencing, we examined the sequence of intron 2 in seven wild-type CYP21 genes and determined the frequency of polymorphisms at nt395, nt453, and nt601 in 48 chromosomes from the parental generation of Centre d’Étude du Polymorphisme Humain families. The observed frequencies of bases at these positions were as follows: 395C, 0.17; 395T, 0.83; 453C, 0.71; 453T, 0.29; 601A, 0.1; and 601C, 0.9. Using a PCR/restriction digestion approach to examine these intragenic markers, we could follow the segregation of alleles in informative families with 21-hydroxylase deficiency and identify deletions of CYP21. We emphasize that this method should be used in conjunction with other molecular genetic techniques for diagnosis of CAH. In addition to their potential use in families with CAH, these markers may be of use in genetic studies of the MHC in humans.
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Affiliation(s)
- Anthony A Killeen
- Department of Pathology, University of Michigan, 1301 Catherine Street, Ann Arbor, MI 48109-0602
| | - Renée R Jiddou
- Department of Pathology, University of Michigan, 1301 Catherine Street, Ann Arbor, MI 48109-0602
| | - Kumud S Sane
- Department of Pediatrics, University of Minnesota, Minneapolis, MN 55455
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Krone N, Roscher AA, Schwarz HP, Braun A. Comprehensive analytical strategy for mutation screening in 21-hydroxylase deficiency. Clin Chem 1998. [DOI: 10.1093/clinchem/44.10.2075] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Congenital adrenal hyperplasia (CAH) is an autosomal recessive disease with a wide range of clinical manifestations. It is most often caused by deficiency of steroid 21-hydroxylase, reflecting any of a wide range of mutations in the 21-hydroxylase (CYP21) gene. A major challenge in molecular diagnostics of CAH is the high homology between the CYP21 gene and the CYP21P pseudogene and the phenomenon of apparent gene conversion, which inactivates the functional gene. In this study we devised an improved stepwise diagnostic procedure involving nonradioactive Southern blotting and direct DNA sequencing. This strategy led to a successful elucidation of the molecular cause of the disease in 181 out of 182 unrelated alleles in a total of 91 clinically and biochemically characterized patients. We were able to identify all classical known disease-causing mutations of the 21-hydroxylase gene and a novel nonsense mutation (bp 670, A→C, Y97X). Our method also allows the reliable, secure diagnosis of the heterozygous configuration and may therefore be used for pre-, peri-, and postnatal diagnosis of CAH, even when informative data of the index patient are lacking. Furthermore, it can be used to confirm the diagnosis of CAH in newborns detected in 17-hydroxyprogesterone screening programs.
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Nelson NC. Rapid detection of genetic mutations using the chemiluminescent hybridization protection assay (HPA): overview and comparison with other methods. Crit Rev Clin Lab Sci 1998; 35:369-414. [PMID: 9791746 DOI: 10.1080/10408369891234228] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The detection of genetic mutations is of paramount importance for the study, diagnosis, and treatment of human genetic disease. Methods of detection generally fall into one of two categories: those to scan for unknown mutations and those to detect known mutations. This review focuses on methods for the detection of known mutations. The hybridization protection assay (HPA) is described in detail. The HPA method utilizes short oligonucleotide probes covalently labeled with a highly chemiluminescent acridinium ester (AE). The assay format is completely homogeneous, requiring no physical separation steps, and can rapidly and sensitively detect all single-base mismatches as well as multiple mismatches, insertions, deletions, and genetic translocations. When very low copy number targets are assayed, HPA is coupled with transcription-mediated amplification (TMA), an isothermal method that amplifies DNA or RNA targets. Other methods that are described for the detection of known mutations include hybridization with sequence-specific oligonucleotides, hybridization to oligonucleotide arrays, allele-specific amplification, ligase-mediated detection, primer extension, and restriction fragment analysis. The advantages and limitations of each of these methods are discussed. Methods to scan for unknown mutations are briefly described.
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Affiliation(s)
- N C Nelson
- Gen-Probe Incorporated, San Diego, CA 92111, USA
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