PDX1 and type 2 diabetes mellitus: Absence of PDX1 is the genetic lesion in the type 4 form of MODY (MODY4) in the heterozygous state and causes pancreatic agenesis in the homozygous state, while partial loss-of-function mutations increase the risk of developing Type 2 diabetes but do not directly cause the disease1, 18, 19, 20, 21.