There is quite the list of "more common" diagnoses found in the trans populace than genpop:
Chronic Bowel Diseases:
Crohns Disease, Ulcerative Colitis, IBS.
Connective Tissue Disorders:
Rheumatoid Arthritis, Ehlers-Danlos, Marfan, Lupus etc
(the above means Raynauds as an issue with blood circulation is also common)
Hormone disorders:
PCS and AIS
Autism, ADHD/ADD.
Some you may be aware of prior to transition, some you may become aware of after in the "oh so thats why my body has always done that". Transition can heighten certain conditions, reduce symptoms or bring them into a new light through different changes to the body or the sudden onset of being in your body and no longer ethereally detached from it as a coping mechanism.
The list above is worthwhile looking through and briefly reading up on, partly because you're going to meet a lot of people in community who have these issues, but also because it may be you who does.