Transcriptional Profiling Shows Dampening of Interferon Gene Signatures by NAD⁺ Augmentation in Ataxia-Telangiectasia

Ataxia-Telangiectasia (A-T) is a multisystem disorder caused by loss of A-T mutated (ATM) protein activity, characterized clinically by immunodeficiency and cerebellar ataxia. ATM is a master regulator of DNA damage responses and loss of ATM function is accompanied by persistent activation of PARP1 leading to depletion of intracellular NAD⁺ and dysfunction of a series of cellular signalling pathways dependent on NAD⁺, providing a mechanistic rationale for NAD⁺ augmentation therapy. We performed a clinical trial of NAD⁺ augmentation with nicotinamide riboside (NR) over 24 months in A-T patients where we observed improved coordination and eye movements in A-T patients. Here, by using peripheral blood mononuclear cells, we performed longitudinal transcriptome profiling to define molecular signatures of A-T and to assess pathway-level responses to NR supplementation. A-T patients exhibited reproducible transcriptomic alterations involving immune, vascular, and inflammatory pathways. NAD⁺ augmentation was associated with suppression of interferon response genes and modulation of networks correlated with neurological improvement. These findings establish systemic molecular signatures of A-T and identify potential blood-based biomarkers that reflect disease processes and therapeutic response, supporting the use of NAD⁺ augmentation as a disease-modifying strategy in A-T by dampening interferon signalling.