In recently years, more and more human NTE/PNPLA6 mutations have been identified to be linked to various complex nervous system diseases, such as hereditary spastic paraplegia 39 (SPG39), Boucher–Neuhäuser syndrome, Gordon–Holmes syndrome, Oliver–McFarlane syndrome and Laurence–Moon syndrome [29,30]. Here, PNPLA6 is linked to hereditary spastic paraplegia 39.