PROJECT SUMMARY/ ABSTRACT Cerebellar ataxia is a disabling symptom and can have a variety of causes, among which immune-mediated gluten ataxia is one of the most common causes. Gluten ataxia is associated with autoimmunity against transglutaminase 6 (TG6) and some patients with gluten ataxia will respond to gluten-free diet. However, the responses to gluten-free diet in patients with gluten ataxia might be variable and there is no clear understanding how TG6 could play a role in ataxia and/or in response to gluten-free diet. Recently, genetic mutations of TGM6, the gene that encodes TG6 protein, have been identified to cause spinocerebellar ataxia type 35 (SCA35). We recently identified a SCA35 patient with a truncated TGM6 mutation and cerebellar ataxia, and his ataxia improved with gluten-free diet, demonstrating that both genetic and immune- mediated causes can converge at the TG6 biology, which serves as a window to probe the dietary contribution in neurological disorders. In this R03 proposal, we will establish the first mouse model of SCA35 and monitor its responses to gluten-diet in ataxia progression (Specific Aim 1), neurophysiology (Specific Aim 2), and neuropathology (Specific Aim 3). This mouse model will serve as a benchmark for future mechanistic studies to understand gluten biology and cerebellar ataxia.