Several metabolic pathways were affected upon stat5b mutation, and the expression of candidate genes related to the growth traits and stat5b function, such as greb1 (growth regulating estrogen receptor binding 1—an estrogen receptor-regulated tumor promoter), lepr (leptin receptor—involved in the regulation of body weight), and igf2b (insulin-like growth factor 2b—diverse functions in organ development) was modified. The gene discussed is STAT5B; the disease is neoplasm.