For decades, infants with Duarte galactosemia (DG) have been identified by newborn screening (NBS), but whether they should be treated with dietary restrictions of galactose has remained unknown. To clarify, we conducted a study of dietary and developmental outcomes in 206 children with DG (case patients) and 144 controls, all of whom were 6 to 12 years old.
We recruited case patients from states where they were identified by NBS; unaffected siblings served as controls. Diet in infancy was ascertained by retrospective parent surveys; developmental outcomes were assessed in 5 domains, yielding 73 outcome measures for each child. We divided subjects randomly into independent discovery (n = 87) and validation (n = 263) sets. We tested the discovery set to order the 73 outcome measures by ascending P values and tested the 10 outcomes with the lowest P values for possible association with DG in the validation set. We also tested these same 10 outcomes for possible association with milk exposure in infancy among case patients in the validation set.
None of the 73 outcomes tested in the discovery set revealed significant association with DG, and none of the 10 outcomes tested in the validation set revealed either significant association with DG or significant association with milk exposure among children with DG.
Through our results, we demonstrated that there were no significant differences in outcomes tested between case patients and controls or among case patients as a function of milk exposure in infancy. In this study, we provide a long-needed foundation of knowledge for health care providers, families, and NBS professionals seeking to make evidence-based decisions about DG.