CLPB and severe congenital neutropenia: More recently, it was reported that missense mutations in the ATP-binding site of SKD3 are also responsible for severe congenital neutropenia (SCN)8,9, an inborn error of granulopoiesis but without 3-methylglutaconic aciduria, suggesting that non-overlapping SKD3 mutations affecting the ATPase activity can be causal for either MGCA7 or SCN.