PNPLA6 and hereditary spastic paraplegia: Chromosome 19 embody three regions p13, q12, and q13.12 linked with AR HSP with homozygous/complex heterozygous alteration in Patatin-Like Phospholipase Domain Containing 6 (SPG39/PNPLA6), Chromosome 19 Open Reading Frame 12 (SPG43/C19ORF12), and Myelin Associated Glycoprotein (SPG75/MAG), respectively.