No, an LOA from medical school could be due to many reasons. Medical, psych, personal, pursuing another degree, etc. You'll get a chance to explain it on your application (there is a specific question about whether or not you took an LOA, and if so you get to write a short summary of why). You don't need anything "official" from your Dean as you'll have your MSPE/Dean's letter, and it can be explained also in that. Will you be screwed for the USMLE? Well, that's up to you. If you go away for 1 year and don't read/study/review anything, then perhaps. If you spend the year reviewing 1st year stuff, and maybe even starting on 2nd year stuff, you might even do better. From a PD perspective, the major issue is whether a long leave like this is likely to recur. If your father gets the care he needs and you can move on with your studies, then I expect you'd be fine. If he remains chronically ill and you require other leaves, or you try to "push through it" and your grades suffer, that wouldn't be good. Going to medical school with the plan of "being a surgeon" is fine, but you could get disappointed in the end. It might have nothing to do with the LOA, but might be due to Step 1, grades, LOR's, etc. If you are not successful getting a GS spot, you'll always wonder whether the LOA was a problem (although, again, if it's a resolved issue I expect not many will care). I guess my point is that going to medical school to "only be a surgeon" is a risk by itself, even without an LOA.