Three diseases, namely Neurofibromatosis type 1 (OMIM 162200), Duchenne/Becker muscular dystrophies (OMIM 310200), and Methylmalonic aciduria mut (0) type (OMIM 251000), which were caused by variants in the NF1, DMD, and MUT (MIM 609058) genes, were observed in 14 diagnosed infants (19.44%, 14/72). The gene discussed is MMUT; the disease is Methylmalonic aciduria.