Day 23 has 23 genes, including CFH (complement factor H.) The CFH protein helps protect your cells from being attacked by part of your immune system (the complement system.) The complement system finds bacteria and pokes holes in their cell walls, killing them. CFH makes sure this system takes aim at bacteria and not your own cells.
One common mutation in CFH, Y402H (rs1061170), strongly influences your chance of developing age-related macular degeneration. 27% of chromosomes carry the mutation, meaning that 44% of people worldwide have either one or two copies of the mutation (ranging from 9% in East Asians to about 60% in Africans and Europeans). Having two copies of the mutation raises your risk 6-fold. It is very unusual for common variants to have such a strong effect on disease.
Click here to see Day 23, jumping to the Y402H mutation flashing.