PDGFB stands for "platelet derived growth factor subunit B". Along with AMD, it's also associated with 'primary brain calcification'. It seems the common thread is capillaries. I'm something of a noob to the circulatory system, but capillaries look to be one of the more complicated parts (regulating flow, letting immune cells through when necessary - more going on in the brain).

Brain *calcification* makes me think of vitamin K2 - for reasons I've gone into. I checked the 'certain vitamins' link to see if the study predates the discovery of K2, but I get a "we can't find that page" when I follow it.