G6PD and lysosomal storage disease: For function-based bioanalysis, DBS storage temperatures greater than 4°C reduced the activity of all five enzymes measured to diagnose newborns at risk of lysosomal storage disorders, with the degree of variability dependent on the properties of a specific enzyme.120–123 Quantitative measurements of glucose-6-phosphate dehydrogenase (G6PD) are used by both malaria and newborn screening programs to identify individuals deficient of this essential enzyme.