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Duraisamy AJ, Liu R, Sureshkumar S, Rose R, Jagannathan L, da Silva C, Coovadia A, Ramachander V, Chandrasekar S, Raja I, Sajnani M, Selvaraj SM, Narang B, Darvishi K, Bhayal AC, Katikala L, Guo F, Chen-Deutsch X, Balciuniene J, Ma Z, Nallamilli BRR, Bean L, Collins C, Hegde M. Focused Exome Sequencing Gives a High Diagnostic Yield in the Indian Subcontinent. J Mol Diagn 2024; 26:510-519. [PMID: 38582400 DOI: 10.1016/j.jmoldx.2024.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 09/11/2023] [Accepted: 03/01/2024] [Indexed: 04/08/2024] Open
Abstract
The genetically isolated yet heterogeneous and highly consanguineous Indian population has shown a higher prevalence of rare genetic disorders. However, there is a significant socioeconomic burden for genetic testing to be accessible to the general population. In the current study, we analyzed next-generation sequencing data generated through focused exome sequencing from individuals with different phenotypic manifestations referred for genetic testing to achieve a molecular diagnosis. Pathogenic or likely pathogenic variants are reported in 280 of 833 cases with a diagnostic yield of 33.6%. Homozygous sequence and copy number variants were found as positive diagnostic findings in 131 cases (15.7%) because of the high consanguinity in the Indian population. No relevant findings related to reported phenotype were identified in 6.2% of the cases. Patients referred for testing due to metabolic disorder and neuromuscular disorder had higher diagnostic yields. Carrier testing of asymptomatic individuals with a family history of the disease, through focused exome sequencing, achieved positive diagnosis in 54 of 118 cases tested. Copy number variants were also found in trans with single-nucleotide variants and mitochondrial variants in a few of the cases. The diagnostic yield and the findings from this study signify that a focused exome test is a good lower-cost alternative for whole-exome and whole-genome sequencing and as a first-tier approach to genetic testing.
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Affiliation(s)
| | - Ruby Liu
- Revvity Omics, Pittsburgh, Pennsylvania
| | | | - Rajiv Rose
- PerkinElmer Genomics, Revvity Omics, Chennai, India
| | | | | | | | | | | | - Indu Raja
- PerkinElmer Genomics, Revvity Omics, Chennai, India
| | | | | | | | | | | | | | - Fen Guo
- Revvity Omics, Pittsburgh, Pennsylvania
| | | | | | | | | | - Lora Bean
- Revvity Omics, Pittsburgh, Pennsylvania
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Pande S, Majethia P, Nair K, Rao LP, Mascarenhas S, Kaur N, do Rosario MC, Neethukrishna K, Chaurasia A, Hunakunti B, Jadhav N, Xavier S, Kumar J, Bhat V, Bhavani GS, Narayanan DL, Yatheesha BL, Patil SJ, Nampoothiri S, Kamath N, Aroor S, Bhat Y R, Lewis LE, Sharma S, Bajaj S, Sankhyan N, Siddiqui S, Nayak SS, Bielas S, Girisha KM, Shukla A. De novo variants underlying monogenic syndromes with intellectual disability in a neurodevelopmental cohort from India. Eur J Hum Genet 2023:10.1038/s41431-023-01513-7. [PMID: 38114583 PMCID: PMC7616498 DOI: 10.1038/s41431-023-01513-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 09/21/2023] [Accepted: 11/27/2023] [Indexed: 12/21/2023] Open
Abstract
The contribution of de novo variants as a cause of intellectual disability (ID) is well established in several cohorts reported from the developed world. However, the genetic landscape as well as the appropriate testing strategies for identification of de novo variants of these disorders remain largely unknown in low-and middle-income countries like India. In this study, we delineate the clinical and genotypic spectrum of 54 families (55 individuals) with syndromic ID harboring rare de novo variants. We also emphasize on the effectiveness of singleton exome sequencing as a valuable tool for diagnosing these disorders in resource limited settings. Overall, 46 distinct disorders were identified encompassing 46 genes with 51 single-nucleotide variants and/or indels and two copy-number variants. Pathogenic variants were identified in CREBBP, TSC2, KMT2D, MECP2, IDS, NIPBL, NSD1, RIT1, SOX10, BRWD3, FOXG1, BCL11A, KDM6B, KDM5C, SETD5, QRICH1, DCX, SMARCD1, ASXL1, ASXL3, AKT3, FBN2, TCF12, WASF1, BRAF, SMARCA4, SMARCA2, TUBG1, KMT2A, CTNNB1, DLG4, MEIS2, GATAD2B, FBXW7, ANKRD11, ARID1B, DYNC1H1, HIVEP2, NEXMIF, ZBTB18, SETD1B, DYRK1A, SRCAP, CASK, L1CAM, and KRAS. Twenty-four of these monogenic disorders have not been previously reported in the Indian population. Notably, 39 out of 53 (74%) disease-causing variants are novel. These variants were identified in the genes mainly encoding transcriptional and chromatin regulators, serine threonine kinases, lysosomal enzymes, molecular motors, synaptic proteins, neuronal migration machinery, adhesion molecules, structural proteins and signaling molecules.
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Affiliation(s)
- Shruti Pande
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Purvi Majethia
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Karthik Nair
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Lakshmi Priya Rao
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Selinda Mascarenhas
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Namanpreet Kaur
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Michelle C do Rosario
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Kausthubham Neethukrishna
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Ankur Chaurasia
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Bhagesh Hunakunti
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Nalesh Jadhav
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Sruthy Xavier
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Jeevan Kumar
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Vivekananda Bhat
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Gandham SriLakshmi Bhavani
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Dhanya Lakshmi Narayanan
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - B L Yatheesha
- Dheemahi Child Neurology and Development Center, Shivamogga, India
| | - Siddaramappa J Patil
- Division of Medical Genetics, Mazumdar Shaw Medical Center, Narayana Hrudayalaya Hospitals, Bangalore, India
| | - Sheela Nampoothiri
- Department of Pediatric Genetics, Amrita Institute of Medical Sciences & Research Centre, Cochin, India
| | - Nutan Kamath
- Department of Paediatrics, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Manipal, India
| | - Shrikiran Aroor
- Department of Paediatrics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Ramesh Bhat Y
- Department of Paediatrics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Leslie E Lewis
- Department of Paediatrics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Suvasini Sharma
- Neurology Division, Department of Pediatrics, Lady Hardinge Medical College and Associated Kalawati Saran Children's Hospital, New Delhi, India
| | | | - Naveen Sankhyan
- Pediatric Neurology Unit, Department of Pediatrics, Advanced Pediatrics Centre, Postgraduate Institute of Medical Education & Research, Chandigarh, India
| | - Shahyan Siddiqui
- Department of Neuro and Vascular Interventional Radiology, Yashoda Hospitals, Secunderabad, Hyderabad, India
| | - Shalini S Nayak
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Stephanie Bielas
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, United States of America
| | - Katta Mohan Girisha
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
- Suma Genomics Private Limited, Manipal Center for Biotherapeutics Research, Manipal Academy of Higher Education, Manipal, India
- Department of Genetics, College of Medicine & Health Sciences, Sultan Qaboos University, Muscat, Oman
| | - Anju Shukla
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India.
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