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Fanis P, Skordis N, Toumba M, Picolos M, Tanteles GA, Neocleous V, Phylactou LA. The pathogenic p.Gln319Ter variant is not causing congenital adrenal hyperplasia when inherited in one of the duplicated CYP21A2 genes. Front Endocrinol (Lausanne) 2023; 14:1156616. [PMID: 37324257 PMCID: PMC10266209 DOI: 10.3389/fendo.2023.1156616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 05/04/2023] [Indexed: 06/17/2023] Open
Abstract
Objective The study aimed to identify the pathogenic status of p.Gln319Ter (NM_000500.7: c.955C>T) variant when inherited in a single CYP21A2 gene (bimodular RCCX haplotype) and to discriminate between a non-causing congenital adrenal hyperplasia (CAH) allele when inherited in a duplicated and functional CYP21A2 gene context (trimodular RCCX haplotype). Methods 38 females and 8 males with hyperandrogenemia, previously screened by sequencing and identified as carriers for the pathogenic p.Gln319Ter, were herein tested by multiplex ligation-dependent probe amplification (MLPA) and a real-time PCR Copy number Variation (CNV) assay. Results Both MLPA and real-time PCR CNV analyses confirmed a bimodular and pathogenic RCCX haplotype with a single CYP21A2 in 19/46 (41.30%) p.Gln319Ter carriers and who in parallel all shared elevated 17-OHP levels. The remaining 27 individuals that also carried the p.Gln319Ter exhibited low 17-OHP levels as a result of their carriership of a duplicated CYP21A2 with a trimodular RCCX haplotype. Interestingly, all of these individuals also carried in linkage disequilibrium with p.Gln319Ter two single nucleotide polymorphisms, the c.293-79G>A (rs114414746) in intron 2 and the c.*12C>T (rs150697472) in the 3'-UTR. Therefore, these variants can be used to distinguish between pathogenic and non-pathogenic genomic contexts of the c.955T (p.Gln319) in the genetic diagnosis of congenital adrenal hyperplasia (CAH). Conclusion The employed methodologies identified a considerable number of individuals with non-pathogenic p.Gln319Ter from the individuals that typically carry the pathogenic p.Gln319Ter in a single CYP21A2. Therefore, it is extremely important the detection of such haplotypes for the prenatal diagnosis, treatment and genetic counseling in patients with CAH.
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Affiliation(s)
- Pavlos Fanis
- Department of Molecular Genetics, Function and Therapy, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Nicos Skordis
- Department of Molecular Genetics, Function and Therapy, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
- Division of Paediatric Endocrinology, Paedi Center for specialized Paediatrics, Nicosia, Cyprus
- School of Medicine, University of Nicosia, Nicosia, Cyprus
| | - Meropi Toumba
- Department of Molecular Genetics, Function and Therapy, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
- Department of Paediatrics, Paediatric Endocrinology Clinic, Aretaeio Hospital, Nicosia, Cyprus
| | - Michalis Picolos
- Department of Endocrinology, Alithias Endocrinology Center, Nicosia, Cyprus
| | - George A. Tanteles
- Department of Clinical Genetics, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Vassos Neocleous
- Department of Molecular Genetics, Function and Therapy, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Leonidas A. Phylactou
- Department of Molecular Genetics, Function and Therapy, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
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Doleschall M, Darvasi O, Herold Z, Doleschall Z, Nyirő G, Somogyi A, Igaz P, Patócs A. Quantitative PCR from human genomic DNA: The determination of gene copy numbers for congenital adrenal hyperplasia and RCCX copy number variation. PLoS One 2022; 17:e0277299. [PMID: 36454796 PMCID: PMC9714944 DOI: 10.1371/journal.pone.0277299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 10/25/2022] [Indexed: 12/05/2022] Open
Abstract
Quantitative PCR (qPCR) is used for the determination of gene copy number (GCN). GCNs contribute to human disorders, and characterize copy number variation (CNV). The single laboratory method validations of duplex qPCR assays with hydrolysis probes on CYP21A1P and CYP21A2 genes, residing a CNV (RCCX CNV) and related to congenital adrenal hyperplasia, were performed using 46 human genomic DNA samples. We also performed the verifications on 5 qPCR assays for the genetic elements of RCCX CNV; C4A, C4B, CNV breakpoint, HERV-K(C4) CNV deletion and insertion alleles. Precision of each qPCR assay was under 1.01 CV%. Accuracy (relative error) ranged from 4.96±4.08% to 9.91±8.93%. Accuracy was not tightly linked to precision, but was significantly correlated with the efficiency of normalization using the RPPH1 internal reference gene (Spearman's ρ: 0.793-0.940, p>0.0001), ambiguity (ρ = 0.671, p = 0.029) and misclassification (ρ = 0.769, p = 0.009). A strong genomic matrix effect was observed, and target-singleplex (one target gene in one assay) qPCR was able to appropriately differentiate 2 GCN from 3 GCN at best. The analysis of all GCNs from the 7 qPCR assays using a multiplex approach increased the resolution of differentiation, and produced 98% of GCNs unambiguously, and all of which were in 100% concordance with GCNs measured by Southern blot, MLPA and aCGH. We conclude that the use of an internal (in one assay with the target gene) reference gene, the use of allele-specific primers or probes, and the multiplex approach (in one assay or different assays) are crucial for GCN determination using qPCR or other methods.
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Affiliation(s)
- Márton Doleschall
- Molecular Medicine Research Group, Eotvos Lorand Research Network and Semmelweis University, Budapest, Hungary
- * E-mail:
| | - Ottó Darvasi
- Hereditary Tumours Research Group, Eotvos Lorand Research Network and Semmelweis University, Budapest, Hungary
| | - Zoltán Herold
- Department of Internal Medicine and Oncology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Zoltán Doleschall
- Department of Pathogenetics, National Institute of Oncology, Budapest, Hungary
| | - Gábor Nyirő
- Molecular Medicine Research Group, Eotvos Lorand Research Network and Semmelweis University, Budapest, Hungary
- Department of Internal Medicine and Oncology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Anikó Somogyi
- Department of Internal Medicine and Hematology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Péter Igaz
- Molecular Medicine Research Group, Eotvos Lorand Research Network and Semmelweis University, Budapest, Hungary
- Department of Internal Medicine and Oncology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
- Department of Endocrinology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Attila Patócs
- Hereditary Tumours Research Group, Eotvos Lorand Research Network and Semmelweis University, Budapest, Hungary
- Department of Internal Medicine and Hematology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
- Department of Molecular Genetics, National Institute of Oncology, Budapest, Hungary
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Abstract
The term CAH-X was coined to describe a subset of patients with 21-hydroxylase deficiency displaying a phenotype compatible with the hypermobility type of Ehlers Danlos syndrome. The genetic defect is due to the monoallelic presence of a CYP21A2 deletion extending into the gene encoding tenascin X (TNXB), a connective tissue extracellular matrix protein. The result is a chimeric TNXA/TNXB gene causing tenascin-X haploinsufficiency. The prevalence of CAH-X was estimated to be around 14-15% in large cohorts of patients with 21-hydroxylase deficiency. However, population studies are still scarce and the clinical picture of the syndrome has yet to be fully defined. In this review, we discuss the current knowledge regarding the genetic and clinical profile of the CAH-X syndrome.
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Karaoğlan M, Nacarkahya G, Aytaç EH, Keskin M. Challenges of CYP21A2 genotyping in children with 21-hydroxylase deficiency: determination of genotype-phenotype correlation using next generation sequencing in Southeastern Anatolia. J Endocrinol Invest 2021; 44:2395-2405. [PMID: 33677812 DOI: 10.1007/s40618-021-01546-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 02/26/2021] [Indexed: 10/22/2022]
Abstract
BACKGROUND/PURPOSE Although it is known that there is generally a good correlation between genotypes and phenotypes, the number of studies reporting discrepancies has recently increased, exclusively between milder genotypes and their phenotypes due to the complex nature of the CYP21A2 gene and methodological pitfalls. This study aimed to assess CYP21A2 genotyping in children with 21-hydroxylase deficiency (21-OHD) and establish their predictive genotype-phenotype correlation features using a large cohort in Southeastern Anatolia's ethnically diverse population. METHODS The patients were classified into three groups: salt-wasting (SW), simple virilizing (SV) and non-classical (NC). The genotypes were categorized into six groups due to residual enzyme activity: null-A-B-C-D-E. CYP21A2 genotyping was performed by sequence-specific primer and sequenced with next generation sequencing (NGS), and the expected phenotypes were compared to the observed phenotypes. RESULTS A total of 118 unrelated children with 21-OHD were included in this study (61% SW, 24.5% SV and 14.5% NC). The pathogenic variants were found in 79.5% of 171 mutated alleles (60.2%, 22.2%, and 17.6% in SW, SV and NC, respectively). Patient distribution based on genotype groups was as follows: null-16.1%, A-41.4%, B-6.0%, C-14.4%, E-22%). In2G was the most common pathogenic variant (33.9% of all alleles) and the most common variant in the three phenotype groups (SW-38.8%, SV-22.2% and NC-23.3%). The total genotype-phenotype correlation was 81.5%. The correlations of the null and A groups were 100% and 76.1%, respectively, while it was lower in group B and poor in group C (71.4% and 23.5%, respectively). CONCLUSION This study revealed that the concordance rates of the severe genotypes with their phenotypes were good, while those of the milder genotypes were poor. The discrepancies could have resulted from the complex characteristics of 21-OHD genotyping and the limitations of using NGS alone without integrating with other comprehensive methods.
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Affiliation(s)
- M Karaoğlan
- Department of Pediatric Endocrinology, Gaziantep University Faculty of Medicine, Gaziantep, Turkey.
| | - G Nacarkahya
- Department of Molecular Biology, Gaziantep University Faculty of Medicine, Gaziantep, Turkey
| | - E H Aytaç
- Department of Pediatric Endocrinology, Gaziantep University Faculty of Medicine, Gaziantep, Turkey
| | - M Keskin
- Department of Pediatric Endocrinology, Gaziantep University Faculty of Medicine, Gaziantep, Turkey
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Carrozza C, Foca L, De Paolis E, Concolino P. Genes and Pseudogenes: Complexity of the RCCX Locus and Disease. Front Endocrinol (Lausanne) 2021; 12:709758. [PMID: 34394006 PMCID: PMC8362596 DOI: 10.3389/fendo.2021.709758] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 07/19/2021] [Indexed: 11/13/2022] Open
Abstract
Copy Number Variations (CNVs) account for a large proportion of human genome and are a primary contributor to human phenotypic variation, in addition to being the molecular basis of a wide spectrum of disease. Multiallelic CNVs represent a considerable fraction of large CNVs and are strictly related to segmental duplications according to their prevalent duplicate alleles. RCCX CNV is a complex, multiallelic and tandem CNV located in the major histocompatibility complex (MHC) class III region. RCCX structure is typically defined by the copy number of a DNA segment containing a series of genes - the serine/threonine kinase 19 (STK19), the complement 4 (C4), the steroid 21-hydroxylase (CYP21), and the tenascin-X (TNX) - lie close to each other. In the Caucasian population, the most common RCCX haplotype (69%) consists of two segments containing the genes STK19-C4A-CYP21A1P-TNXA-STK19B-C4B-CYP21A2-TNXB, with a telomere-to-centromere orientation. Nonallelic homologous recombination (NAHR) plays a key role into the RCCX genetic diversity: unequal crossover facilitates large structural rearrangements and copy number changes, whereas gene conversion mediates relatively short sequence transfers. The results of these events increased the RCCX genetic diversity and are responsible of specific human diseases. This review provides an overview on RCCX complexity pointing out the molecular bases of Congenital Adrenal Hyperplasia (CAH) due to CYP21A2 deficiency, CAH-X Syndrome and disorders related to CNV of complement component C4.
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Affiliation(s)
- Cinzia Carrozza
- Dipartimento di Scienze di Laboratorio e Infettivologiche, UOC Chimica, Biochimica e Biologia Molecolare Clinica, Fondazione Policlinico Universitario “Agostino Gemelli” IRCCS, Roma, Italy
- Dipartimento di Scienze Biotecnologiche di base, Cliniche Intensivologiche e Perioperatorie, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Laura Foca
- Dipartimento di Scienze di Laboratorio e Infettivologiche, UOC Chimica, Biochimica e Biologia Molecolare Clinica, Fondazione Policlinico Universitario “Agostino Gemelli” IRCCS, Roma, Italy
| | - Elisa De Paolis
- Dipartimento di Scienze di Laboratorio e Infettivologiche, UOC Chimica, Biochimica e Biologia Molecolare Clinica, Fondazione Policlinico Universitario “Agostino Gemelli” IRCCS, Roma, Italy
| | - Paola Concolino
- Dipartimento di Scienze di Laboratorio e Infettivologiche, UOC Chimica, Biochimica e Biologia Molecolare Clinica, Fondazione Policlinico Universitario “Agostino Gemelli” IRCCS, Roma, Italy
- *Correspondence: Paola Concolino,
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A rare CYP21A2 haplotype clarifies the phenotype-genotype discrepancy in an Italian patient with Non Classical Congenital Adrenal Hyperplasia (NC-CAH). Mol Biol Rep 2020; 47:3049-3052. [PMID: 32185686 DOI: 10.1007/s11033-020-05379-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 03/12/2020] [Indexed: 10/24/2022]
Abstract
RCCX haplotypes with two copies of the CYP21A2 gene and one copy of the CYP21A1P pseudogene have been widely described in different populations. In most cases, the CYP21A2-like gene downstream of the TNXA gene showed a wild-type sequence or the c.293-13A/C > G variant while the CYP21A2 gene next to TNXB carried the p.(Gln319Ter) variant. Here is the discovery of a novel rare CYP21A2 haplotypes detected in an Italian patient with Non Classical Congenital Adrenal Hyperplasia (NC-CAH). The molecular family study was performed clarifying the previously found phenotype-genotype discrepancy.
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Abstract
Congenital adrenal hyperplasia (CAH) is a group of seven autosomal recessively inherited disorders of various enzymes participating in adrenal steroid hormone synthesis. Patients present with various symptoms depending on the nature and severity of the enzymatic block. More than 95% of all CAH patients suffer from 21-hydroxylase deficiency. The genetic background is well characterized for all CAH subtypes. Characterization of their genetic background has provided important pathophysiologic understanding of steroid biosynthesis disorders. Genotyping is important for confirming diagnosis, determining prognostic factors, and for genetic counseling for family planning and may reveal new therapeutic approaches.
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Affiliation(s)
- Dóra Török
- 2nd Department of Pediatrics, Semmelweis University, Budapest, Hungary.
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