Fig. 1.

Algorithm for the detection of genetic disorders and acquired vitamin B₁₂, from 2015 to nowadays. Cut-off values in μmol/L: C3: initial strategy: < 4.5 (99th ptl); current strategy: 3.5 (96th ptl); Met: 7–35 (1th ptl and 99.7th ptl, respectively); C17: < 0.1 (99.9th ptl); C3/C2 ratio: < 0.2 (99.8th ptl); C3/Met ratio: < 0.43 (99.8th ptl). Ptl percentile. CblA methylmalonic acidemia CblA type, CblB methylmalonic acidemia CblB type, CblC methylmalonic acidemia with homocystinuria CblC type, CblD methylmalonic acidemia with homocystinuria CblD type, CblE methylmalonic acidemia with homocystinuria CblE type, CblF methylmalonic acidemia with homocystinuria CblF type, CblG homocystinuria CblG type, CblJ methylmalonic acidemia with homocystinuria CblJ type, CblX methylmalonic acidemia with homocystinuria CblX type, CBS cystathionine β-synthase deficiency, C17 heptadecanoilcarnitine, C2 acetylcarnitine, C3 propionylcarnitine, Hcys homocysteine, MCA methylcitric acid, Met methionine, MMA methylmalonic acid, MS methionine synthase, MTHFR methylenetetrahydrofolate reductase, MUT methylmalonyl-CoA mutase deficiency, NBS newborn screening, PA propionic acidemia