Erythrocyte Galactose-1-phosphate measurement by GC-MS in the monitoring of classical galactosemia

Background. Classical galactosemia is a rare but very severe disease characterized by a deficiency of the galactose-1-phosphate uridyltransferase enzyme. The confirmed galactosemic patients are treated with a galactose-restricted diet. Nevertheless, metabolites such as galactose-1-phosphate can accumulate in red blood cells of treated patients and its measurement is a standard practice for their monitoring. At present, no commercial methods for measuring galactose-1-phosphate in erythrocytes are available. Methods. In this study, we will describe the optimization and laboratory validation of a previously published quantitative gas chromatographic-mass spectrometric method and its clinical validation on normal donors and galactosemic patients both at the diagnosis and during the follow-up. Results. The method was technically optimized and validated for its clinical use on normal donors and galactosemic newborns, children and adults. The method was suitable for the monitoring of dietary compliance. Galactose-1-phosphate levels were found to be well correlated with the clinical signs in the galactosemic patients at the follow-up. Conclusions. This paper provides information on the measurement of Galactose-1-phosphate levels that can be very useful for the management of classical galactosemia.