We performed a pathway analysis for the UCD and iMCD cases and found that the genes involved in the mitogen-activated protein kinase (MAPK) pathways (FAS, PDGFRB, FGFR3, NF1, and TGFBR2) were most commonly affected in UCD (p = 0.001 (Reactome)). The gene discussed is PDGFRB; the disease is urea cycle disorder.