When a shinobi overuses the mangekyou sharingan, other than the vision (blindness), does he lose any other abilities as well? If so, what are they?
I was also wondering for a bit as well as I do know that it eventually makes the user blind which leads them to snatching the eyes from a blood relative Sharingan user. Whether that impacts their abilities is something I wasn't sure of.
But, fret not, now I am!
Once Mangekyou Sharingan has been awakened, it grants them a lot nice extra's, but also the negative effect of turning blind over time. As far as I could find, the only negative effect is blindness, meaning that they retain their abilities from their eyes. Of course, it might be a bit difficult to cast Amaterasu accurately based on the sound of footsteps when you're blind, but that is essentially what is possible.
When they awaken the eternal variant, they can unlock eventually what they had with their original eyes. Meaning that in the end, they gain a lot more.
So in short to answer your question, no, you don't. You only lose your sight unless you have the eternal variant.
They do not lose fire-weilding and other genjustu learned however when they lose their sight they do lose the Sharingan abilities. What happens is their eyes lose light and in essence, die. If they retained the eyes abilities, Madara would have had no need to steal as many eyes as he had, for his other senses would have filled in and in essence made the Sharingan stronger with practice without actual sight (much like Daredevil). Loss of sight= loss of Sharingan. That creates hatred among the clan though because when an Uchiha outuses his abilities, he steals them from another clan member.