A Reliable Method Using In-house Prepared Reagents For Total Galactose Measurement As A Screening Tool For Galactosaemia
Galactosaemia is an autosomal recessive inherited disorder of galactose metabolism. Classical galactosaemia (CG), a disorder due to galactose-1-phosphate uridyl transferase (GALT) deficiency, is the most common and severe form in Caucasian population. In Malaysia, the incidence of Galactosaemia is still unknown. Currently, the diagnosis of galactosaemia in Malaysia is using commercialized kit which is expensive. The purpose of this studies is to establish and evaluate the method for total galactose (TG) assay utilising in-house prepared reagents and to diagnosis of classical galactosemia among high risk neonates and infants in Malaysia. The TG assay was based on the enzymatic end point assay using fluorometer measurement. Performance characteristics were determined for this method and reference range were established using dried blood spot samples from normal healthy babies. The validated TG assay was then used as a screening marker in 5313 neonates and infants with prolonged jaundice to make diagnosis of galactosaemia. The TG calibrators showed linearity up to 10000 μM while the precision coefficient variation (CV) was less than 10%. Limit of detection and quantitation were 56 and 176 µmol/L respectively. Glucose and ascorbic acids were found to have interference with TG assay. Comparison study of the TG assay with commercial kits showed a significant relationship (p<0.05). From this screening, two patients were diagnosed as CG, galactokinase or galactose-4-epimerase deficiency (n=5) and citrin deficiency (n=10). In conclusion, TG assay method was successfully established and validated in Malaysia and also serves as a confirmatory test for diagnosis of citrin deficiency diagnosis.