Sodium-glucose cotransporters SGLT1 (encoded by SGLT1, also known as SLC5A1) and SGLT2 (encoded by SGLT2, also known as SLC5A2) are important mediators of epithelial glucose transport. Mutations in the SLC5A1 gene cause glucose/galactose malabsorption, whereas mutations in SLC5A2 are associated with glucosuria. Congenital glucose-galactose malabsorption (cGGM) is a rare autosomal recessive disorder, caused by mutations in the Na(+)/glucose cotransporter gene SLC5A1, which may result in severe life-threatening osmotic diarrhea due to the accumulation of unabsorbed sugars in the intestinal lumen. If treated early with the elimination of glucose and galactose from the diet, patients usually recover and develop normally. More than 300 subjects of diverse origin have been reported worldwide, most of whom are a result of a consanguineous union.