BACKGROUND: Protein kinase RNA-like endoplasmic reticulum kinase (PERK) is an endoplasmic reticulum stress kinase whose loss of function disturbs human development, leading to skeletal dysplasia and permanent neonatal diabetes, as in the Wolcott-Rallison Syndrome (WRS). The gene discussed is EIF2AK3; the disease is Wolcott-Rallison syndrome.