GRIK4 and episodic ataxia type 6: Episodic ataxia type 6 (EA6) is caused by mutations in SLC1A3. This gene encodes excitatory amino acid transporter 1 (EAA1), which is a glial glutamate transporter that clears glutamate from the synaptic cleft and regulates neurotransmitter concentrations at excitatory glutamatergic synapses [43].