Galactitol and galactonate in red blood cells of children with the Duarte/galactosemia genotype

We measured galactitol, galactonate, and galactose-1-phosphate in the red blood cell (RBC) to elucidate the biochemical phenotype of infants with a Duarte/galactosemia (D/G) genotype by isotope dilution GC/MS. The RBC galactonate, galactitol and Gal-1-P were quantified in 14 D/G newborns on a lactose containing formula or breast milk, eight D/G newborns on a galactose-free formula, and 18 D/G children between 1 and 2 years of age that were on a regular diet. The results were compared with those of non-galactosemic subjects of comparable age. In the D/G newborns on regular formula/breast milk, the levels of RBC galactitol, galactonate, and Gal-1-P were significantly higher than those of D/G newborns on diet treatment and non-galactosemic newborns. There was no difference in the levels of RBC galactitol, galactonate, and Gal-1-P between D/G newborns on a lactose-restricted diet and the control group. There appears to be two different responses to dietary galactose intake in D/G children. The first group of D/G children placed on a regular diet after a year of lactose restriction had higher RBC galactitol, galactonate levels than those of non-galactosemic children. The mean level of RBC galactonate was higher and the mean value of RBC galactitol was as high as that of galactosemic (G/G) patients on diet treatment. The second group of D/G children on a regular diet had normal levels of RBC galactitol and galactonate. The levels of RBC Gal-1-P were normal in both groups of D/G patients. The alternative pathway products may reflect galactose intake better than RBC Gal-1-P in D/G children.