Analysis performed on human mammary epithelial cells (HMECs) incubated in medium supplemented with 15% of LS patients’ serum showed that these cells are characterized by reduced levels of RAS, PKA and TOR, leading to reduced DNA damage and increase apoptosis upon stimulation with oxidative stress compared to cells incubated with 15% of serum derived from LS patients’ relatives, not affected by GHR deficiency [6]. The gene discussed is RORC; the disease is Leigh syndrome.