Though a review of the genetics of HSP and role of REEP1 and the other mentioned proteins is beyond the scope of this review, it is apparent that loss of REEP1 function can have major effects of ER structure and neuronal function, eventually leading to neurodegeneration of spinal cord motor neurons and development of HSP (Blackstone, 2018a). The gene discussed is REEP1; the disease is hereditary spastic paraplegia.