INS and gestational diabetes: The HHEX gene has been mapped to the 23.33 region in the long arm of chromosome 10 (10q23.33), with a total length of 5.7 kb and 4 introns.[10] In recent years, several studies have confirmed that HHEX is a GDM susceptibility gene.[11–14] Changes in HHEX expression, associated with its polymorphism, may contribute to altered paracrine regulation of insulin secretion.