ED is not associated with thal minor, but then again, almost none of the things thal minors suffer from are officially associated with thal minor, which remains asymptomatic according to most "authorities."
Priapism is associated with sickle cell disease, which is a disorder of the beta globin gene, just like beta thal is also caused by the beta globin gene. Although sickling is not present in most thals (with a specific type of Hemoglobin C being the exception), I would ask are there similarities that would duplicate the mechanics of sickle cell which cause priapism? My own take on this is yes, there may be some similarities between the effect of sickling in blood vessels and the "clutter" found in the blood of thalassemics. If this "clutter" builds in the blood vessels in the penis, could priapism be the result? This may be the first time this question has even been asked. Don't expect anyone to go out and research this, as the problems of thal minors are virtually ignored by medical research and doctors.