A Missense Mutation in PPP1R15B Causes a Syndrome Including Diabetes, Short Stature, and Microcephaly

Dysregulated endoplasmic reticulum stress and phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2 alpha) are associated with pancreatic beta-cell failure and diabetes. Here, we report the first homozygous mutation in the PPP1R15B gene (also known as constitutive repressor of eIF2 alpha phosphorylation [CReP]) encoding the regulatory subunit of an eIF2 alpha-specific phosphatase in two siblings affected by a novel syndrome of diabetes of youth with short stature, intellectual disability, and microcephaly. The R658C mutation in PPP1R15B affects a conserved amino acid within the domain important for protein phosphatase 1 (PP1) binding. The R658C mutation decreases PP1 binding and eIF2 alpha dephosphorylation and results in beta-cell apoptosis. Our findings support the concept that dysregulated eIF2 alpha phosphorylation, whether decreased by mutation of the kinase (EIF2AK3) in Wolcott-Rallison syndrome or increased by mutation of the phosphatase (PPP1R15B), is deleterious to beta-cells and other secretory tissues, resulting in diabetes associated with multisystem abnormalities.