GLUT-1 is a fructose transporter [39], and upregulation of expression in the AC of the HE-C group may reflect an imbalance between the fructose needs of an embryo that initially developed in an HE donor mare and presumed lower supply of fructose in the uterine environment of a control recipient mare. The gene discussed is SLC2A1; the disease is hereditary elliptocytosis.