After diagnosis, exclusive HMF was reported in 64 HM‐fed infants: n = 37/48 (77%) HM‐fed infants with MCAD deficiency, n = 4/8 with LCHAD or VLCAD deficiency, n = 1/1 with CPTII deficiency, n = 3/4 with OTC deficiency, n = 2/2 with arginase deficiency, n = 1/2 with CPS1 deficiency, n = 2/2 with GALE deficiency, n = 8/14 with MMA, n = 4/12 with PA, n = 1/1 with MA, and n = 1/1 with hypermethioninemia (Table S3). Here, CPS1 is linked to disorder of methionine catabolism.