Explaining heritability for a disease, which is the portion of risk shaped by genetics, has been a question that has puzzled scientists for decades. Much of what we know has been found from studies of twins or other closely related families. However, much of the “missing heritability” for complex disorders, which are influenced by both genetic and environmental risk factors, is unknown.
Andrea Waksmunski and Michelle Grunin, postdoctoral fellows from the Department of Population and Quantitative Health Sciences and members of the CWRU Postdoctoral Association, set out to unravel missing heritability in age-related macular degeneration (AMD), the leading cause of blindness in individuals over age 65. They identified that two novel genes for AMD contribute a small portion of heritability, and the known genes contribute another 44-62% of heritability. Beyond the individual effects of individual genes, interactions between genes (also called epistatic interactions) may be another contributor to AMD genetics. This adds another piece to the puzzle of the genetic architecture of AMD.