Mannose supplementation in PMM2-CDG.

In this response to the letter by Witters et al., we refer to the authors' arguments regarding spontaneous enhancement of glycosylation and the claim, that mannose has no place in the treatment of PMM2-CDG. Our paper "Dietary mannose supplementation in phosphomannomutase 2 deficiency (PMM2-CDG)" has shown that further investigation of mannose in PMM2-CDG is worthwhile alongside other treatment options and should not be dismissed off-hand without the willingness to prove or disprove it in controlled prospective clinical trials.