In adult pancreas, EIF2AK3 is expressed extensively in the islet, with a predominance in B cells. The normal birth weights of infants with Wolcott-Rallison syndrome and the unremarkable pancreatic organogenesis in Eif2ak3 -/- mice might suggest a minimal role for EIF2AK3 during pancreatic development in utero. Also, EIF2AK3 is widely expressed within the human fetal pancreas at eight weeks postconception, at which stage the organ is composed of epithelial progenitor cells before islet or exocrine differentiation. Taken together, these observations indicate that the human fetal pancreas may not be normal in Wolcott-Rallison syndrome. Consistent with this suggestion, mutation of the Eif2ak3 enzyme target (Ser51Ala of Eif2a) results in a 50% diminution of pancreatic insulin content between mouse embryonic days 16.5 and 18.5.