Prenatal identification of a heterozygous status in two fetuses at risk for glucose-galactose malabsorption.

Glucose-galactose malabsorption (GGM) is an autosomal recessive disorder which presents with severe osmotic diarrhoea shortly after birth. Two proband siblings with GGM were previously demonstrated to contain a missense mutation (D28N) in the Na(+)-dependent glucose/galactose cotransporter (SGLT1) that accounts for the defect in sugar absorption. Prenatal screening for GGM was performed in two subsequent pregnancies in this large consanguineous family. The first exon of the SGLT1 gene was PCR-amplified from genomic DNA and screened for the presence of the D28N mutation by EcoRV restriction digestion. The proband's sibling was heterozygous and a cousin was not a carrier of the D28N mutation. Both children at 2-years of age remain healthy and have had no diarrhoeal symptoms. Molecular biology techniques will allow a prospective determination of the presence of an abnormal SGLT1 allete and potentially decrease the postnatal morbidity.