Impaired neurite complexity and length has been described in many other forms of HSP including SPG4 (Rehbach et al., 2019), SPG11 (Pérez-Brangulí et al., 2014), SPG15 (Denton et al., 2018) and SPG48 (Denton et al., 2018). Here, AP5Z1 is linked to hereditary spastic paraplegia.