T1DM presents with a variety of clinical features and is classified into three types, according to the mode of onset: typical acute-onset type; SPIDDM, which presents with T2DM pathology at the time of diagnosis and endogenous insulin secretion gradually decreases, with progression to insulin dependence; and fulminant type, characterized by a rapid destruction of pancreatic β cells, leading to severe hyperglycemia which can sometimes be fatal. The gene discussed is INS; the disease is type 1 diabetes mellitus.