Glucose-galactose transporter DEFICIENCY: a diagnosis based on clinical observations.

Dehydration and major diarrhea in young infants is mainly linked to infectious diseases. However in case leading to denutrition and growth retardation, metabolic causes or malabsorption should be evocated. We report here the case of a few days old infant admitted for early recurrence of liquid stools and vomiting.

XX is born at term (3450 grams, 51 cm) after an uneventful pregnancy. Consanguinity has been reported in the family. He was breastfed but presented rapidly liquid stools and vomiting. At 10 days old he was first admitted for dehydration, loss of weight below his birth weight (2900 grams) and severe hypernatremia. Semi elementary diet led to some improvement but he was readmitted at the age of one month for similar even worse symptoms including abdominal distension and explosive stools. Complementary investigations have excluded infection, parasitosis, malformation and immune deficits. Different diet formulas were tried with no significant benefit what led to the placement of parenteral nutrition thanks to which weight was gained. Hypothesis of peculiar carbohydrate malabsorption was made and the following tests have been carried out:
-Clinitest: presence of reducing substances in the stools.
-Lactose Breath test: between 15 and 90 ppm H2 with a peak value at 90 ppm H2 after 90 minutes.
-Duodenal biopsy: normal histology; normal activity of lactase, maltase, saccharase-isomaltase.
Considering the normality of these enzyme activities, hypothesis of “Na-dependant glucose-galactose transporter” deficit was put forward. This was confirmed according to the results of HGPO and glucose breath test. Search for SGTL1 gene mutation is still in progress.

In conclusion despite of the huge progresses made at molecular biology level, clinical observation remain essential to the diagnosis of malabsorption. Precise reporting of the used milk formula and comparative analysis of their composition can orient the diagnosis and help to select the most accurate molecular test. Here, analyses exclude every enzyme activity deficiencies. Carbohydrate malabsorption from first days of live can be linked to a glucose-galactose transporter deficiency due to a SGLT1 mutation (chr 22). This autosomal recessive disorder has only been reported 200 times until now.