First-line screening is by serum transferrin isoelectrofocusing. It shows a type 2 pattern in the reported patients. This pattern is possibly normal in some patients, as in some patients with other COG-CDG (COG4-CDG and COG6-CDG). Six (likely) pathogenic variants have been reported: missense variant c.904G>A (p.Val302Met), nonsense variant c.614-615delTT (p.Lys205Serfs*7), intronic variant c.435+2T>C (p.Val107_Gln145del), missense variant c.170-7A>G (p.56-57insAT), intronic variant c.IVS1+4A>C and missense variant c.1717C>T (p.Arg573Trp).
COG7