GAPDH binds to the carboxyl terminal of β-amyloid precursor protein (APP) and amyloid beta protein (Aβ) implicated in Alzheimer’s disease (AD) (Schulze et al, 1993; Oyama et al, 2000) and to other mutant proteins that contain expanded polyglutamine repeats, such as atrophin-1 implicated in dentatorubral-pallidoluysian atrophy (DRPLA) and ataxin-1, which causes spinocerebellar ataxia type 1 (SCA-1) (Burke et al, 1996; Koshy et al, 1996). The gene discussed is ATN1; the disease is spinocerebellar ataxia type 1.