Important unanswered issues include: (1) Which particular essential amino acids control the ability of retinal blood vessel cells to form new vessels, (2) How sensors for amino acid shortages (like HRI and GCN2) communicate with factors that encourage vessel growth, and (3) Whether adjusting metabolic pathways could offer new treatments to slow down AMD. The gene discussed is EIF2AK4; the disease is age-related macular degeneration.