[Intestinal malabsorption of glucose and galactose. Study of a family].

A girl with congenital glucose-galactose malabsorption and her two parents were studied. Hydrogen breath tests performed on the child during glucose and galactose tolerance tests (0.5 g/kg) were positive (increase in expired pH concentration of 21 p.p.m. and 32.5 p.p.m. from the basal level respectively). This was negative for fructose (2 g/kg). In vitro intestinal transport studies showed: 1) a selective decrease in active glucose accumulation (intracellular concentration 0.34 mM in 0.1 mM glucose bathing solution - controls: 1.58 +/- 0.56 (means +/- SD), and 12.1 mM in 10 mM bathing solution - controls: 38.4 +/- 12.4). 2) absence of net glucose absorption during in vitro Ussing chamber measurements with a marked decrease in mucosal membrane glucose permeability. For the parents, the hydrogen breath test was negative after glucose and galactose ingestion (2 g/kg) and intestinal transport was normal (father; intracellular concentration 1.32 mM and mother 2.04 for 0.1 mM bathing glucose concentration). The marked decrease in brush border permeability explains the absence of net glucose absorption in the child. The parents who are presumed to be heterozygotes did not exhibit any detectable transport defect.