From what I am able to find, if it is a genuinely medical issue (and being born XXY would qualify) if you decided to seek gender reassignment surgery this would be allowed Islamically. Not all scholars have agreed with this (there are plenty who side with the idea that you are as Allah made you) but there have been many fatwas issued that allow it as well. The delineating factors tend to be the sect, school, and basic liberalness of the person issuing the fatwa. My recommendation (and Allah knows best) would be to seek a fatwa for yourself after doing plenty of research and have that research ready to provide the person giving the fatwa.