Recessive loss-of-function mutations in EIF2S3 (15), DNAJC3 [encoding a BiP co-chaperone (16)] and PPP1R15B [encoding a constitutive repressor of eIF2α phosphorylation (17)] all result in syndromic early-onset monogenic diabetes subtypes with excessive signaling downstream of PERK. This evidence concerns the gene EIF2AK3 and diabetes mellitus.