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Tyagi N, Uppili B, Sharma P, Parveen S, Saifi S, Jain A, Sonakar A, Ahmed I, Sahni S, Shamim U, Anand A, Suroliya V, Asokachandran V, Srivastava A, Sivasubbu S, Scaria V, Faruq M. Investigation of RFC1 tandem nucleotide repeat locus in diverse neurodegenerative outcomes in an Indian cohort. Neurogenetics 2024; 25:13-25. [PMID: 37917284 DOI: 10.1007/s10048-023-00736-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 10/10/2023] [Indexed: 11/04/2023]
Abstract
An intronic bi-allelic pentanucleotide repeat expansion mutation, (AAGGG)400-2000, at AAAAG repeat locus in RFC1 gene, is known as underlying genetic cause in cases with cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) and late-onset sporadic ataxia. Biallelic positive cases carry a common recessive risk haplotype, "AAGA," spanning RFC1 gene. In this study, our aim is to find prevalence of bi-allelic (AAGGG)exp in Indian ataxia and other neurological disorders and investigate the complexity of RFC1 repeat locus and its potential association with neurodegenerative diseases in Indian population-based cohorts. We carried out repeat number and repeat type estimation using flanking PCR and repeat primed PCR (AAAAG/AAAGG/AAGGG) in four Indian disease cohorts and healthy controls. Haplotype assessment of suspected cases was done by genotyping and confirmed by Sanger sequencing. Blood samples and consent of all the cases and detailed clinical details of positive cases were collected in collaboration with A.I.I.M.S. Furthermore, comprehension of RFC1 repeat locus and risk haplotype analysis in Indian background was performed on the NGS data of Indian healthy controls by ExpansionHunter, ExpansionHunter Denovo, and PHASE analysis, respectively. Genetic screening of RFC1-TNR locus in 1998 uncharacterized cases (SCA12: 87; uncharacterized ataxia: 1818, CMT: 93) and 564 heterogenous controls showed that the frequency of subjects with bi-allelic (AAGGG)exp are 1.15%, < 0.05%, 2.15%, and 0% respectively. Two RFC1 positive sporadic late-onset ataxia cases, one bi-allelic (AAGGG)exp and another, (AAAGG)~700/(AAGGG)exp, had recessive risk haplotype and CANVAS symptoms. Long normal alleles, 15-27, are significantly rare in ataxia cohort. In IndiGen control population (IndiGen; N = 1029), long normal repeat range, 15-27, is significantly associated with A3G3 and some rare repeat motifs, AGAGG, AACGG, AAGAG, and AAGGC. Risk-associated "AAGA" haplotype of the original pathogenic expansion of A2G3 was found associated with the A3G3 representing alleles in background population. Apart from bi-allelic (AAGGG)exp, we report cases with a new pathogenic expansion of (AAAGG)exp/(AAGGG)exp in RFC1 and recessive risk haplotype. We found different repeat motifs at RFC1 TNR locus, like AAAAG, AAAGG, AAAGGG, AAAAGG, AAGAG, AACGG, AAGGC, AGAGG, and AAGGG, in Indian background population except ACAGG and (AAAGG)n/(AAGGG)n. Our findings will help in further understanding the role of long normal repeat size and different repeat motifs, specifically AAAGG, AAAGGG, and other rare repeat motifs, at the RFC1 locus.
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Affiliation(s)
- Nishu Tyagi
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Bharathram Uppili
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Pooja Sharma
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Shaista Parveen
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
| | - Sheeba Saifi
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
| | - Abhinav Jain
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Akhilesh Sonakar
- Department of Neurology, Neuroscience Centre, All India Institute of Medical Sciences (AIIMS), 110608, New Delhi, India
| | - Istaq Ahmed
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
| | - Shweta Sahni
- Department of Neurology, Neuroscience Centre, All India Institute of Medical Sciences (AIIMS), 110608, New Delhi, India
| | - Uzma Shamim
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
| | - Avni Anand
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
| | - Varun Suroliya
- Department of Neurology, Neuroscience Centre, All India Institute of Medical Sciences (AIIMS), 110608, New Delhi, India
| | - Vivekanand Asokachandran
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Achal Srivastava
- Department of Neurology, Neuroscience Centre, All India Institute of Medical Sciences (AIIMS), 110608, New Delhi, India
| | - Sridhar Sivasubbu
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
| | - Vinod Scaria
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India
| | - Mohammed Faruq
- Genomics and Molecular Medicine Division, CSIR - Institute of Genomics and Integrative Biology, New Delhi, 110007, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
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Bajaj A, Senthivel V, Bhoyar R, Jain A, Imran M, Rophina M, Divakar MK, Jolly B, Verma A, Mishra A, Sharma D, Deepti S, Sharma G, Bansal R, Yadav R, Scaria V, Naik N, Sivasubbu S. 1029 genomes of self-declared healthy individuals from India reveal prevalent and clinically relevant cardiac ion channelopathy variants. Hum Genomics 2022; 16:30. [PMID: 35932045 PMCID: PMC9354277 DOI: 10.1186/s40246-022-00402-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 07/11/2022] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND The prevalence and genetic spectrum of cardiac channelopathies exhibit population-specific differences. We aimed to understand the spectrum of cardiac channelopathy-associated variations in India, which is characterised by a genetically diverse population and is largely understudied in the context of these disorders. RESULTS We utilised the IndiGenomes dataset comprising 1029 whole genomes from self-declared healthy individuals as a template to filter variants in 36 genes known to cause cardiac channelopathies. Our analysis revealed 186,782 variants, of which we filtered 470 variants that were identified as possibly pathogenic (440 nonsynonymous, 30 high-confidence predicted loss of function ). About 26% (124 out of 470) of these variants were unique to the Indian population as they were not reported in the global population datasets and published literature. Classification of 470 variants by ACMG/AMP guidelines unveiled 13 pathogenic/likely pathogenic (P/LP) variants mapping to 19 out of the 1029 individuals. Further query of 53 probands in an independent cohort of cardiac channelopathy, using exome sequencing, revealed the presence of 3 out of the 13 P/LP variants. The identification of p.G179Sfs*62, p.R823W and c.420 + 2 T > C variants in KCNQ1, KCNH2 and CASQ2 genes, respectively, validate the significance of the P/LP variants in the context of clinical applicability as well as for large-scale population analysis. CONCLUSION A compendium of ACMG/AMP classified cardiac channelopathy variants in 1029 self-declared healthy Indian population was created. A conservative genotypic prevalence was estimated to be 0.9-1.8% which poses a huge public health burden for a country with large population size like India. In the majority of cases, these disorders are manageable and the risk of sudden cardiac death can be alleviated by appropriate lifestyle modifications as well as treatment regimens/clinical interventions. Clinical utility of the obtained variants was demonstrated using a cardiac channelopathy patient cohort. Our study emphasises the need for large-scale population screening to identify at-risk individuals and take preventive measures. However, we suggest cautious clinical interpretation to be exercised by taking other cardiac channelopathy risk factors into account.
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Affiliation(s)
- Anjali Bajaj
- grid.417639.eCSIR-Institute of Genomics and Integrative Biology, Sukhdev Vihar, Mathura Road, New Delhi, 110025 India ,grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India
| | - Vigneshwar Senthivel
- grid.417639.eCSIR-Institute of Genomics and Integrative Biology, Sukhdev Vihar, Mathura Road, New Delhi, 110025 India ,grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India
| | - Rahul Bhoyar
- grid.417639.eCSIR-Institute of Genomics and Integrative Biology, Sukhdev Vihar, Mathura Road, New Delhi, 110025 India
| | - Abhinav Jain
- grid.417639.eCSIR-Institute of Genomics and Integrative Biology, Sukhdev Vihar, Mathura Road, New Delhi, 110025 India ,grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India
| | - Mohamed Imran
- grid.417639.eCSIR-Institute of Genomics and Integrative Biology, Sukhdev Vihar, Mathura Road, New Delhi, 110025 India ,grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India
| | - Mercy Rophina
- grid.417639.eCSIR-Institute of Genomics and Integrative Biology, Sukhdev Vihar, Mathura Road, New Delhi, 110025 India ,grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India
| | - Mohit Kumar Divakar
- grid.417639.eCSIR-Institute of Genomics and Integrative Biology, Sukhdev Vihar, Mathura Road, New Delhi, 110025 India ,grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India
| | - Bani Jolly
- grid.417639.eCSIR-Institute of Genomics and Integrative Biology, Sukhdev Vihar, Mathura Road, New Delhi, 110025 India ,grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India
| | - Ankit Verma
- grid.417639.eCSIR-Institute of Genomics and Integrative Biology, Sukhdev Vihar, Mathura Road, New Delhi, 110025 India
| | - Anushree Mishra
- grid.417639.eCSIR-Institute of Genomics and Integrative Biology, Sukhdev Vihar, Mathura Road, New Delhi, 110025 India
| | - Disha Sharma
- grid.417639.eCSIR-Institute of Genomics and Integrative Biology, Sukhdev Vihar, Mathura Road, New Delhi, 110025 India ,grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India
| | - Siddharthan Deepti
- grid.413618.90000 0004 1767 6103Department of Cardiology, All India Institute of Medical Sciences (AIIMS), New Delhi, 110029 India
| | - Gautam Sharma
- grid.413618.90000 0004 1767 6103Department of Cardiology, All India Institute of Medical Sciences (AIIMS), New Delhi, 110029 India
| | - Raghav Bansal
- grid.413618.90000 0004 1767 6103Department of Cardiology, All India Institute of Medical Sciences (AIIMS), New Delhi, 110029 India
| | - Rakesh Yadav
- grid.413618.90000 0004 1767 6103Department of Cardiology, All India Institute of Medical Sciences (AIIMS), New Delhi, 110029 India
| | - Vinod Scaria
- grid.417639.eCSIR-Institute of Genomics and Integrative Biology, Sukhdev Vihar, Mathura Road, New Delhi, 110025 India ,grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India
| | - Nitish Naik
- grid.413618.90000 0004 1767 6103Department of Cardiology, All India Institute of Medical Sciences (AIIMS), New Delhi, 110029 India
| | - Sridhar Sivasubbu
- grid.417639.eCSIR-Institute of Genomics and Integrative Biology, Sukhdev Vihar, Mathura Road, New Delhi, 110025 India ,grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India
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