DBS results of primary biomarkers by individual groups are shown in Fig. 3; C3 and C3/C2 values were clearly above the cut-off values in MUT, CblA, CblB, CblC, and propionic acidemia while patients with SUCLA2 or ACSF3 defects showed values slightly above the cut-off for both biomarkers. Here, MMAA is linked to propionic acidemia.