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. The gene discussed is PMM2; the disease is PMM2-congenital disorder of glycosylation.