[1] This protein is found mainly in the intestinal tract and, to a lesser extent, in the kidneys, where it is involved in transporting glucose and the structurally similar galactose across cell membranes.

[citation needed] Mutations that prevent the sodium/glucose cotransporter protein from performing this function result in a buildup of glucose and galactose in the intestinal tract.

In addition, the water that normally would have been transported across the brush border with the sugar instead remains in the intestinal tract to be expelled with the stool, resulting in dehydration of the body's tissues and severe diarrhea.

[citation needed] This condition is inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered.

In some cases, individuals with one altered gene have reduced levels of glucose absorption capacity as measured in laboratory tests, but this has not generally been shown to have significant health effects.

[2] Treatment mainly consists of introducing formulas that are based on fructose and a regular diet deficient in glucose and galactose (and the disaccharides sucrose and lactose) products and ingredients.