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Spastic paraplegia 20 (Troyer syndrome)
Protein SPG20 PDB 2dl1.png
PDB rendering based on 2dl1.
Available structures
PDB Ortholog search: PDBe, RCSB
External IDs OMIM607111 MGI2139806 HomoloGene32243 GeneCards: SPG20 Gene
RNA expression pattern
PBB GE SPG20 212526 at tn.png
PBB GE SPG20 216965 x at tn.png
More reference expression data
Species Human Mouse
Entrez 23111 229285
Ensembl ENSG00000133104 ENSMUSG00000036580
UniProt Q8N0X7 Q8R1X6
RefSeq (mRNA) NM_001142294 NM_001144987
RefSeq (protein) NP_001135766 NP_001138459
Location (UCSC) Chr 13:
36.88 – 36.94 Mb
Chr 3:
55.11 – 55.14 Mb
PubMed search [1] [2]

Spartin is a protein that in humans is encoded by the SPG20 gene.[1][2][3]

This gene encodes a protein that contains a MIT (Microtubule Interacting and Trafficking molecule) domain. This protein may be involved in endosomal trafficking, microtubule dynamics, or both functions. Frameshift mutations associated with this gene cause autosomal recessive spastic paraplegia 20 (Troyer syndrome).[3]

Troyer syndrome (SPG20) is a complicated type of hereditary spastic paraplegias (HSPs).[4] HSP is a category of neurological disorder characterized by spasticity and muscle weakness in the lower limbs.[4]


The original description of this gene mutation and associated symptoms were described in 1967.[5] This mutation is commonly found in high frequency with the Amish population.[2] Newer studies have found that the mutation is not isolated to the Amish population, but also resides in the Omani population.[5]


This syndrome is not only characterized by spasticity and weakness in the lower limbs, but also with dysarthria, mental retardation or mild developmental delay, and muscle wasting or muscle atrophy.[4]


Individuals appear to have difficulty walking, and report a clumsy, spastic gait which worsens over time.[5] Some additional common physical features include overgrowth of the jaw bone, hammer toes, hand and feet abnormalities, and pes cavus.[5]


Cognitive challenges, including developmental delay and difficulty with performance in school, may affect individuals with this syndrome.[5]


Neurologic examination of individuals with this mutation may show dysmetria in the upper extremities, hyperreflexia, distal amyotrophy and ankle clonus, in addition to spasticity, weakness and dysarthria.[5]

Diagnostic Imaging[edit]

The cerebellar vermis may present with mild atrophy and a loss of white matter volume.[5]

Through Lifespan[edit]

Facial dysmorphism and subtle skeletal features are common in younger children.[5] The condition progressively worsens, as spasticity and distal amyotrophy symptoms are revealed more in teenage years.[5] SPG20 expression in the adult is relatively modest, however it is widespread in the nervous system.[5] Longitudinal comparison of magnetic resonance imaging concluded that there was a progression of the syndrome; thus, the condition appears to worsen over time.[5]


  1. ^ Cross HE, McKusick VA (Jun 1967). "The Troyer syndrome. A recessive form of spastic paraplegia with distal muscle wasting". Arch Neurol 16 (5): 473–85. doi:10.1001/archneur.1967.00470230025003. PMID 6022528. 
  2. ^ a b Patel H, Cross H, Proukakis C, Hershberger R, Bork P, Ciccarelli FD, Patton MA, McKusick VA, Crosby AH (Jul 2002). "SPG20 is mutated in Troyer syndrome, an hereditary spastic paraplegia". Nat Genet 31 (4): 347–8. doi:10.1038/ng937. PMID 12134148. 
  3. ^ a b "Entrez Gene: SPG20 spastic paraplegia 20, spartin (Troyer syndrome)". 
  4. ^ a b c Bakowska, J.C., Jenkins, R., Pendleton, J., Blackstone, C. (2005). "The Troyer syndrome (SPG20) protein interacts with Eps15". Biochemical and Biophysical Research Communications 334 (4): 1042–1048. doi:10.1016/j.bbrc.2005.06.201. PMID 16036216. 
  5. ^ a b c d e f g h i j k Manzini, M. C., Rajab, A., Maynard, T. M., Mochida, G. H., Tan, W., Nasir, R., . . . Walsh, C.A. (2010). "Developmental and degenerative features in a complicated spastic paraplegic.". Annals of Neurology 67: 516–525. doi:10.1002/ana.21923. 

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