Ataxia telangiectasia (Louis Bar syndrome): Clinical, Immunological, and Genetic Insights

Ataxia telangiectasia (A T), also known as Louis-Bar syndrome, is a rare autosomal recessive disorder characterised by progressive neurodegeneration, immunodeficiency, and a heightened predisposition to malignancies. This study provides a comprehensive review of the recent literature to examine the clinical, immunological, and genetic features of A T, highlighting the variability in disease presentation and progression. The majority of patients present with cerebellar ataxia, oculomotor apraxia, and dysarthria, with onset typically in early childhood. Immunological deficiencies, including selective IgA and IgG subclass deficits, contribute to recurrent infections and overall morbidity. The spectrum of ATM gene mutations plays a critical role in determining the severity of neurological symptoms, immune dysfunction, and cancer risk. Genotype-phenotype correlations reveal that truncating mutations often result in more severe clinical manifestations, whereas missense and splicing variants may lead to milder or atypical phenotypes. This review also underscores the importance of early diagnosis, multidisciplinary management, and long-term surveillance to optimise patient outcomes. Although no curative therapies currently exist, advances in understanding ATM function and the molecular pathways affected by its deficiency offer promising avenues for targeted interventions. Overall, an integrated approach combining genetic, clinical, and immunological insights is essential to guide individualised care and improve quality of life for individuals living with A T.