A next-generation sequencing panel analysis was conducted with a focus on the etiology associated with methylmalonic aciduria, involving the genes ABCD4, HCFC1, LMBRD1, MMACHC, and MMADHC. In the analysis, the c.484G > T:p.(Gly162Trp) variant was identified in the homozygous state in the MMACHC gene (NM_015506.3) (Fig. 1). Here, MMACHC is linked to Methylmalonic aciduria.