Mice with sub-renal transplanted pseudo-islets from a pancreatic β-cell line leading to severe hypoglycaemia displayed decreased overall mass of insulin-positive cells in endogenous islets with coinciding β-cell hypotrophy and an increase in apoptotic insulin-positive cells32; attenuated immunoreactivity of insulin in islets and blood glucose levels was normalized within four days after removal of exogenous islets, however, while β-cell size had returned to normal after 21 days, overall insulin-positive cell mass was still decreased. The gene discussed is INS; the disease is Hypoglycemia.