Both SLC39A8-CDG and TMEM165-CDG are caused by disturbed manganese metabolism and might thus be considered secondary glycosylation disorders in which the deficiency of glycosyltransferases is caused by the lack of a cofactor (see section “Manganese-Sulfate Is a Causative Treatment for SLC39A8-CDG” and “A Potential Role for Manganese in the Treatment of TMEM165-CDG,” Figure 2B). The gene discussed is TMEM165; the disease is disorder of glycosylation.