SEMA3A and Motor neuron atrophy: In fact, it is also well known that there is an association of certain semaphorins with other diseases, such as Sema4A with retinal degeneration [141], Sema3A-Np1 signaling with motor neuron degeneration [142,143], Sema3A, Sema7A, and Sema4D with multiple sclerosis [144,145], and Sema3A and Sema5A with Parkinson’s disease [146,147] (see also [47] for review).