For some reason this is something that never seems to stick, and it shows up in lots of ways (UW and NBME both like to test your knowledge of type of inheritance of a certain disease and your knowledge of probabilities by combining them... give an obvious case presentation or actually name the disease, and then ask what the chance of an offspring having the disease or being a carrier or whatever, or showing you a pedigree and asking what disease that might represent). I hate it when I know the pathophys of a disease, presentation, treatments, etc. and can't remember whether it is AR or XR. I know there are a few rules of thumb, like most enzyme deficiencies are AR, and I know a few of the AD diseases off the top of my head that have always stuck, but there are a lot that fall through the cracks and I never can seem to remember the inheritance pattern. Anyone have a mnemonic, catchy story, branding iron, or anything else that might help me retain these? I've tried rote memorization, and much like a lot of biochem pathways it's here one day and gone the next. Seems like this could easily be worth a couple of questions on the test, so its worth the time for me to pound it in somehow.