Among the over 60 genes that have been linked with HSP (Hensiek et al., 2015), many of them are implicated in the formation of ER-endosome MCSs, such as REEP1, WASH complex subunit strumpellin, ER protein protrudin, and spastin (Beetz et al., 2006, 2008; Mannan et al., 2006; Valdmanis et al., 2007). The gene discussed is REEP1; the disease is hereditary spastic paraplegia.