LoF mutations in ITPR1, encoding IP3R type 1, cause Gillepsie syndrome (GLSP), characterized by muscular hypotonia, mydriasis, ataxia, and intellectual disability (Gerber et al., 2016), and Itpr1-null mice manifest severe ataxia and epileptic seizures (Matsumoto et al., 1996). The gene discussed is ITPR1; the disease is cerebellar ataxia.