*PLS HELP, I'LL GIVE 25 POINTS AND BRAINLIEST TO THE RIGHT ANSWER!*
Thomas has a condition where his body does not produce myelin. Myelin forms an insulating layer around cells and allows stimuli to be transmitted between cells and throughout the body.
Which cell type would be affected by Thomas' condition?
Without the body producing myelin the electrical impulses from your brain would not be able to get to the nerve, and therefore most (almost all parts) of your body would not be able to communicate to each other.