The human gene SLC5A2 encodes a sodium-dependent glucose transporter (SGLT2), expressed in many tissues but primarily in the kidney, specifically S1 and S2 proximal tubule segments. It is a low affinity, high capacity transporter of glucose across the apical membrane, with co-transport of Na+ ions in a 1:1 ratio and is the main transporter of glucose in the kidney, responsible for approximately 98% of glucose reabsorption (reaminder by SGLT1). Defects in SLC5A2 are the cause of renal glucosuria (GLYS1; MIM:233100), an autosomal recessive renal tubular disorder characterised by glucosuria in the absence of both hyperglycemia and generalized proximal tubular dysfunction. Mutations that cause GLYS1 include W440*, Q167fs*186, N654S and R479G (van den Heuvel et al. 2002, Calado et al. 2004, Yu et al. 2011).