Additionally, homozygous/compound heterozygous truncating mutations and heterozygous deletions and missense mutations in ITPR1 have been associated with Gillespie syndrome (MIM 206700), a disorder characterized by hypotonia, progressive hypoplasia, ataxia, and variable cognitive impairment with onset occurring within the first year of life [61]. This evidence concerns the gene ITPR1 and cerebellar ataxia.