[30 years' work on congenital glucose and galactose malabsorption: from phenotype to genotype].

Intestinal absorption of glucose plays a key role in water economy as attested by the congenital and selective glucose and galactose malabsorption which is expressed as severe watery diarrhea just after birth, leading to life-threatening dehydration. This syndrome, transmitted on an autosomal recessive mode, is the consequence of a functional defect of the glucose-sodium cotransporter at the luminal membrane of the enterocyte of the small intestine. In one family, this defect was associated with a misense mutation at position 92 of the SGLT1 gene coding for the cotransporter. The mutant RNA reproduced the transport defect after injection in xenopus oocytes. These results confirm the genetic origin of the congenital defect; in addition they indicate that the study of the relationship between phenotype and genotype of congenital defects of intestinal transport may help in the understanding of basic intestinal functions in relation with human nutrition.