Clinical and Molecular Spectrum of Ataxia Telangiectasia in Thirteen Indian Families: A Case Series

Abstract Background: Ataxia-telangiectasia (A-T) is a rare, progressive neurodegenerative disorder caused by biallelic pathogenic variants in ATM, characterised by childhood-onset ataxia, recurrent infections, immunological abnormalities, and oculocutaneous telangiectasia. Objectives: To describe the clinical, laboratory, and molecular spectrum of genetically confirmed A-T in Indian families. Materials and Methods: Thirteen Indian families with genetically confirmed A-T were evaluated. Clinical, laboratory, immunological, and molecular findings were retrospectively reviewed. Exome sequencing was used for molecular diagnosis. Results: We describe thirteen Indian families with genetically confirmed A-T, highlighting their clinical, laboratory, and molecular features. Affected individuals commonly presented with early-onset progressive ataxia, ocular telangiectasia and variable immunoglobulin abnormalities. Exome sequencing identified a total of 18 variants in the ATM gene, including 6 nonsense, 5 frameshift, 4 missense, and 3 splice-site variants. Conclusion: This series highlights the clinical and molecular spectrum of A-T in Indian families and emphasises the importance of early recognition and molecular diagnosis for timely management and genetic counselling.