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Concolino P. Chimeric Genes Causing 11β-Hydroxylase Deficiency: Implications in Clinical and Molecular Diagnosis. Mol Diagn Ther 2024; 28:215-224. [PMID: 38324138 DOI: 10.1007/s40291-024-00697-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/16/2024] [Indexed: 02/08/2024]
Abstract
Deficiency of 11β-hydroxylase (11β-OHD) is the second most common cause of congenital adrenal hyperplasia (CAH), accounting for 0.2-8% of all cases. The disease is transmitted as an autosomal recessive trait and the underlying genetic causes of 11β-OHD are primarily small pathogenic variants affecting the CYP11B1 gene coding the 11β-hydroxylase enzyme. However, special events complicate the molecular diagnosis of 11β-OHD such as an unequal crossing over between the CYP11B2 (coding aldosterone synthase enzyme) and CYP11B1 genes. The resulting allele contains a hybrid gene, with a CYP11B2 5'-end and a CYP11B1 3'-end, where the CYP11B1 gene is under the control of the CYP11B2 promoter and thus not responding to the adrenocorticotropin (ACTH) but to angiotensin II and K+. This leads a reduction of cortisol production in 11β-OHD. In particular, CYP11B2/CYP11B1 chimeric genes can be distinguished into two groups depending on the breakpoint site: chimeras with breakpoint after the exon 5 of CYP11B2 preserve the aldosterone synthase activity, the others with breakpoint before exon 5 lose this function. In the last case, a more severe phenotype is expected. The aim of this review was to explore the setting of CYP11B2/CYP11B1 chimeras in 11β-OHD, performing a careful review of clinical literature cases.
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Affiliation(s)
- Paola Concolino
- Dipartimento di Scienze di Laboratorio e Infettivologiche, UOC Chimica, Biochimica e Biologia Molecolare Clinica, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Largo A. Gemelli 8, 00168, Rome, Italy.
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Wijaya M, Ma H, Zhang J, Du M, Li Y, Chen Q, Guo S. Aldosterone signaling defect in young infants: single-center report and review. BMC Endocr Disord 2021; 21:149. [PMID: 34243750 PMCID: PMC8272273 DOI: 10.1186/s12902-021-00811-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 06/28/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Aldosterone (Ald) is a crucial factor in maintaining electrolyte and water homeostasis. Defect in either its synthesis or function causes salt wasting (SW) manifestation. This disease group is rare, while most reported cases are sporadic. This study aimed to obtain an overview of the etiology and clinical picture of patients with the above condition and report our rare cases. METHODS A combination of retrospective review and case studies was conducted at the Pediatric Endocrine unit of The First Affiliated Hospital Sun Yat Sen University from September 1989 to June 2020. RESULTS A total of 187 patients with SW were enrolled, of which 90.4% (n = 169) were diagnosed with congenital adrenal hyperplasia (CAH). SW type 21-hydroxylase deficiency accounted for 98.8% (n = 167) of CAH diagnosis, while 1.2% (n = 2) was of lipoid CAH. Non-CAH comprised 9.6% (n = 18) of the total patients whose etiologies included SF-1 gene mutation (n = 1), X-linked adrenal hypoplasia congenita (n = 9), aldosterone synthase deficiency (ASD, n = 4), and pseudo-hypoaldosteronism type 1 (PHA1, n = 1). Etiologies were not identified in three patients. All of patients with ASD and PHA1 exhibited SW syndrome in their early neonatal period. DNA sequencing showed mutations of CYP11B2 for P1-P4 and NR3C2 for P5. P1 and P2 were sibling brothers affected by compound heterozygous mutations of c.1121G > A (p.R374Q) and c.1486delC p.(L496fs); likewise, P4 was identified with compound heterozygous mutations of c.1200 + 1G > A and c.240-1 G > T; meanwhile P3 demonstrated c.1303G > A p.(G435S) homozygous mutation in CYP11B2 gene. Lastly, P5 showed c.1768 C > T p.(R590*) heterozygous mutation in the NR3C2 gene. CONCLUSION Etiology of infant with aldosterone defect was mostly congenital. Renal and adrenal imaging are recommended to exclude renal causes. If clinical picture is suggestive, normal plasma Ald in early infancy cannot rule out aldosterone insufficiency.
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Affiliation(s)
- Melati Wijaya
- Department of Pediatrics, The First affiliated Hospital, Sun Yat-Sen University, No. 58, Zhongshan II Rd, Guangzhou, 510080, P. R. China
| | - Huamei Ma
- Department of Pediatrics, The First affiliated Hospital, Sun Yat-Sen University, No. 58, Zhongshan II Rd, Guangzhou, 510080, P. R. China.
| | - Jun Zhang
- Department of Pediatrics, The First affiliated Hospital, Sun Yat-Sen University, No. 58, Zhongshan II Rd, Guangzhou, 510080, P. R. China
| | - Minlian Du
- Department of Pediatrics, The First affiliated Hospital, Sun Yat-Sen University, No. 58, Zhongshan II Rd, Guangzhou, 510080, P. R. China
| | - Yanhong Li
- Department of Pediatrics, The First affiliated Hospital, Sun Yat-Sen University, No. 58, Zhongshan II Rd, Guangzhou, 510080, P. R. China
| | - Qiuli Chen
- Department of Pediatrics, The First affiliated Hospital, Sun Yat-Sen University, No. 58, Zhongshan II Rd, Guangzhou, 510080, P. R. China
| | - Song Guo
- Department of Pediatrics, The First affiliated Hospital, Sun Yat-Sen University, No. 58, Zhongshan II Rd, Guangzhou, 510080, P. R. China
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Jia M, Yang B, Li Z, Shen H, Song X, Gu W. Computational analysis of functional single nucleotide polymorphisms associated with the CYP11B2 gene. PLoS One 2014; 9:e104311. [PMID: 25102047 PMCID: PMC4125216 DOI: 10.1371/journal.pone.0104311] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 07/07/2014] [Indexed: 12/17/2022] Open
Abstract
Single nucleotide polymorphisms (SNPs) are the most common type of genetic variations in humans and play a major role in the genetics of human phenotype variation and the genetic basis of human complex diseases. Recently, there is considerable interest in understanding the possible role of the CYP11B2 gene with corticosterone methyl oxidase deficiency, primary aldosteronism, and cardio-cerebro-vascular diseases. Hence, the elucidation of the function and molecular dynamic behavior of CYP11B2 mutations is crucial in current genomics. In this study, we investigated the pathogenic effect of 51 nsSNPs and 26 UTR SNPs in the CYP11B2 gene through computational platforms. Using a combination of SIFT, PolyPhen, I-Mutant Suite, and ConSurf server, four nsSNPs (F487V, V129M, T498A, and V403E) were identified to potentially affect the structure, function, and activity of the CYP11B2 protein. Furthermore, molecular dynamics simulation and structure analyses also confirmed the impact of these nsSNPs on the stability and secondary properties of the CYP11B2 protein. Additionally, utilizing the UTRscan, MirSNP, PolymiRTS and miRNASNP, three SNPs in the 3'UTR region were predicted to exhibit a pattern change in the upstream open reading frames (uORF), and eight microRNA binding sites were found to be highly affected due to 3'UTR SNPs. This cataloguing of deleterious SNPs is essential for narrowing down the number of CYP11B2 mutations to be screened in genetic association studies and for a better understanding of the functional and structural aspects of the CYP11B2 protein.
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Affiliation(s)
- Minyue Jia
- Department of Endocrinology and Metabolism, the Second Affiliated Hospital Zhejiang University School of Medicine, Hangzhou, China
| | - Boyun Yang
- Department of Endocrinology and Metabolism, the Second Affiliated Hospital Zhejiang University School of Medicine, Hangzhou, China
| | - Zhongyi Li
- Department of Urology, the Second Affiliated Hospital (Binjiang Branch) Zhejiang University School of Medicine, Hangzhou Binjiang Hospital, Hangzhou, China
| | - Huiling Shen
- Department of Endocrinology and Metabolism, the Second Affiliated Hospital Zhejiang University School of Medicine, Hangzhou, China
| | - Xiaoxiao Song
- Department of Endocrinology and Metabolism, the Second Affiliated Hospital Zhejiang University School of Medicine, Hangzhou, China
| | - Wei Gu
- Department of Endocrinology and Metabolism, the Second Affiliated Hospital Zhejiang University School of Medicine, Hangzhou, China
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Todkar A, Picard N, Loffing-Cueni D, Sorensen MV, Mihailova M, Nesterov V, Makhanova N, Korbmacher C, Wagner CA, Loffing J. Mechanisms of renal control of potassium homeostasis in complete aldosterone deficiency. J Am Soc Nephrol 2014; 26:425-38. [PMID: 25071088 DOI: 10.1681/asn.2013111156] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Aldosterone-independent mechanisms may contribute to K(+) homeostasis. We studied aldosterone synthase knockout (AS(-/-)) mice to define renal control mechanisms of K(+) homeostasis in complete aldosterone deficiency. AS(-/-) mice were normokalemic and tolerated a physiologic dietary K(+) load (2% K(+), 2 days) without signs of illness, except some degree of polyuria. With supraphysiologic K(+) intake (5% K(+)), AS(-/-) mice decompensated and became hyperkalemic. High-K(+) diets induced upregulation of the renal outer medullary K(+) channel in AS(-/-) mice, whereas upregulation of the epithelial sodium channel (ENaC) sufficient to increase the electrochemical driving force for K(+) excretion was detected only with a 2% K(+) diet. Phosphorylation of the thiazide-sensitive NaCl cotransporter was consistently lower in AS(-/-) mice than in AS(+/+) mice and was downregulated in mice of both genotypes in response to increased K(+) intake. Inhibition of the angiotensin II type 1 receptor reduced renal creatinine clearance and apical ENaC localization, and caused severe hyperkalemia in AS(-/-) mice. In contrast with the kidney, the distal colon of AS(-/-) mice did not respond to dietary K(+) loading, as indicated by Ussing-type chamber experiments. Thus, renal adaptation to a physiologic, but not supraphysiologic, K(+) load can be achieved in aldosterone deficiency by aldosterone-independent activation of the renal outer medullary K(+) channel and ENaC, to which angiotensin II may contribute. Enhanced urinary flow and reduced activity of the thiazide-sensitive NaCl cotransporter may support renal adaptation by activation of flow-dependent K(+) secretion and increased intratubular availability of Na(+) that can be reabsorbed in exchange for K(+) secreted.
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Affiliation(s)
- Abhijeet Todkar
- Institutes of Anatomy and Physiology, and Zurich Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | | | | | | | | | - Viatcheslav Nesterov
- Institute for Cellular and Molecular Physiology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany; and
| | - Natalia Makhanova
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, North Carolina
| | - Christoph Korbmacher
- Institute for Cellular and Molecular Physiology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany; and
| | - Carsten A Wagner
- Physiology, and Zurich Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Johannes Loffing
- Institutes of Anatomy and Zurich Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland;
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Hui E, Yeung MCW, Cheung PT, Kwan E, Low L, Tan KCB, Lam KSL, Chan AOK. The clinical significance of aldosterone synthase deficiency: report of a novel mutation in the CYP11B2 gene. BMC Endocr Disord 2014; 14:29. [PMID: 24694176 PMCID: PMC3976226 DOI: 10.1186/1472-6823-14-29] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 03/31/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Aldosterone synthase (CYP11B2) deficiency is a rare autosomal recessive disorder, usually presenting with severe salt-wasting in infancy or stress-induced hyperkalaemia and postural hypotension in adulthood. Neonatal screening for congenital adrenal hyperplasia, another cause of salt wasting, using 17-hydroxyprogesterone measurement would fail to detect aldosterone synthase deficiency, a diagnosis which may be missed until the patient presents with salt-wasting crisis. Due to this potential life-threatening risk, comprehensive hormonal investigation followed by genetic confirmation for suspected patients would facilitate clinical management of the patient and assessment of the genetic implication in their offspring. CASE PRESENTATION We describe a 33-year old Chinese man who presented in infancy with life-threatening hyponatraemia and failure to thrive, but remained asymptomatic on fludrocortisone since. Chromosomal analysis confirmed a normal male karyotype of 46, XY. Plasma steroid profile showed high plasma renin activity, low aldosterone level, and elevated 18-hydroxycorticosterone, compatible with type 2 aldosterone synthase deficiency. The patient was heterozygous for a novel CYP11B2 mutation: c.977C > A (p.Thr326Lys) in exon 3. He also carried a heterozygous mutation c.523_525delAAG (p.Lys175del) in exon 6, a known pathogenic mutation causing aldosterone synthase deficiency. Sequencing of CYP11B2 in his parents demonstrated that the mother was heterozygous for c.977C > A, and the father was heterozygous for c.523_525delAAG. CONCLUSION Although a rare cause of hyperreninaemic hypoaldosteronism, aldosterone synthase deficiency should be suspected and the diagnosis sought in patients who present with life-threatening salt-wasting in infancy, as it has a good long-term prognosis when adequate fludrocortisone replacement is instituted. To our knowledge, this is the first Chinese patient in which the molecular basis of aldosterone synthase deficiency has been identified.
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Affiliation(s)
- Elaine Hui
- Department of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Pokfulam, Hong Kong
| | - Matthew CW Yeung
- Department of Pathology, The University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Pokfulam, Hong Kong
| | - Pik To Cheung
- Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Pokfulam, Hong Kong
| | - Elaine Kwan
- Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Pokfulam, Hong Kong
| | - Louis Low
- Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Pokfulam, Hong Kong
| | - Kathryn CB Tan
- Department of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Pokfulam, Hong Kong
| | - Karen SL Lam
- Department of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Pokfulam, Hong Kong
| | - Angel OK Chan
- Department of Pathology, The University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Pokfulam, Hong Kong
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