The SPG20 gene encodes a protein of 666 amino acids with molecular weight of about 73 kDa. The Spartin protein contains a Microtubule-Interacting and Trafficking molecule (MIT) domain in the N-terminus. It localizes to mitochondria and partially co-localizes with microtubules. Spartin is a multifunctional protein, implicated in regulating endosomal trafficking and mitochondria function. It has multiple alternative splice variants, encoding the same protein. Defects in this protein are the cause of autosomal recessive spastic paraplegia 20 (Troyer syndrome), characterized by dysarthria, distal amyotrophy, mild developmental delay and short stature.