I graduated from a top 5 MBA program and the reason why I think I got in was because of my learning disability. Many schools, especially elite graduate schools want to have as diverse student body as possible. That includes race, religion, gender and everything else that can make you different - like a learning disability. Rather than hide it, embrace it, use it to your advantage and talk about it in your essays. Just make sure you can demonstrate that you can also do the work - that is also important.