Seven of 35 children with OAs were “late” diagnosed, between 3 months and 2.5 years (n = 3 methylmalonic acidemia [MMA]; n = 1 propionic acidemia [PA]; n = 2 glutaric aciduria type 1 [GA1]; and n = 1 malonic acidemia [MA]), as well as one of 14 children with a UCD (n = 1 ornithine transcarbamylase [OTC] deficiency, diagnosed at 1.5 years), and 2 of 58 children with FAODs (n = 2 medium‐chain acyl‐coenzyme A dehydrogenase [MCAD] deficiency, diagnosed at 2 months and 3.5 years). The gene discussed is OTC; the disease is medium chain acyl-CoA dehydrogenase deficiency.