SLC1A3 and proximal spinal muscular atrophy: Various studies have implicated loss of EAAT4 and/or GLAST/EAAT1 in the pathogenesis of several disorders affecting the motor system including several subtypes of spinocerebellar ataxia (SCA), SCA1 (3,4), SCA5 (5–7), SCA7 (8), episodic ataxia type 6 (9–11), spinal muscular atrophy (12) and fragile X associated tremor/ataxia syndrome (13).