For example, regulation of ICOS affects outcomes in experimental rodent stroke models by modulating T cells.19 Chorea‐acanthocytosis (ChAc), a neurodegenerative disease, results from loss‐of‐function mutations of the chorein‐encoding gene VPS13A.20 Perhaps smoking induced changes in levels of VPS13A would affect red blood cells and predispose to clotting/stroke. The gene discussed is VPS13A; the disease is Choreoacanthocytosis.