The ITPR1Δ18/wt and ITPR1Δ18/Δ18 mice (mouse models for SCA15/16 [3]) possess heterozygous and homozygous, respectively, in-frame 18 bp deletions in exon 36 of the gene that encodes IP3R1. The gene discussed is ITPR1; the disease is spinocerebellar ataxia type 15/16.