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The Hereditary Spastic Paraplegias
Nine Genes and Counting
John K. Fink, MD
Arch Neurol. 2003;60:1045-1049.
ABSTRACT
The hereditary spastic paraplegias (HSPs) are inherited neurologic disorders in which the primary symptom is insidiously progressive difficulty walking due to lower extremity weakness and spasticity. There have been great strides in our knowledge of this group of disabling disorders; 20 HSP loci and 9 HSP genes have been discovered. Insights into the molecular causes of HSPs are beginning to emerge. This review summarizes these advances in HSPs' genetics.
INTRODUCTION
Hereditary spastic paraplegia (HSP) is a syndromic designation encompassing more than 30 disorders in which the predominant feature is spastic gait.1 The HSP syndromes are classified clinically as uncomplicated (also known as pure or nonsyndromic) if symptoms are limited to progressive spastic weakness in the legs, often accompanied by urinary urgency and subtle dorsal column impairment. The HSP syndromes are classified as complicated or syndromic if the inherited disorder includes other neurologic abnormalities (eg, neuropathy, amyotrophy, ataxia, mental retardation, or thin corpus callosum) or systemic disturbances (eg, cataracts) for which alternate disorders have been excluded. Postmortem studies of uncomplicated HSP have shown axonal degeneration that is most marked in the distal terminals of corticospinal tracts and fasciculus gracilis fibers.2
Symptoms of HSP may begin at any age, from infancy to older than 60 years. If symptoms begin during the teenage years or later, then spastic gait disturbance usually progresses insidiously over many years. Canes, walkers, and wheelchairs may eventually be required. If symptoms begin in late infancy or early childhood, however, then there may be relatively little functional worsening, even over many years. Individuals with early-onset, apparently nonprogressive HSP may be distinguishable from those with spastic diplegic cerebral palsy only by family history (which may be absent in recessive, X-linked, or dominantly inherited HSP with variable age of symptom onset).
Autosomal dominant, autosomal recessive, and X-linked HSP are each genetically heterogeneous. Genetic mapping has identified 20 different HSP loci (Table 1) designated SPG (SPastic parapleGia) 1 through 21 in order of their discovery (SPG18 has been identified but not published). Thus far, 10 loci for autosomal dominant HSP, 7 loci for autosomal recessive HSP, and 3 loci for X-linked HSP have been published. The occurrence of HSP in families for which known HSP loci are excluded indicates the existence of additional loci (J.K.F. and S. Rainier, PhD, unpublished observations, 2003).
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Hereditary Spastic Paraplegia (HSP)*
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Different genetic types of uncomplicated HSP usually cannot be distinguished by clinical and neuroimaging parameters alone. This reflects both the clinical similarity between different types of HSP and the phenotypic variability within a given genetic type of HSP. There may be significant clinical variability both within a given family in which all subjects have the same HSP gene mutation; between families with the same genetic type of HSP; and between families with different genetic types of HSP. For example, some families with SPG4 HSP (due to spastin gene mutations described in the next section) include individuals with child hood-onset symptoms and individuals whose symptoms begin after age 30 years.
FIVE AUTOSOMAL DOMINANT HSP GENES
Spastin
Mutations in the SPG4 gene (spastin protein) are responsible for approximately 40% of autosomal dominant HSP cases.4 Hereditary spastic paraplegia due to SPG4 gene mutation is the single most common form of autosomal dominant HSP, and possibly the single most common form of any type of HSP. At this stage, we know very little about the function of spastin, the encoded protein of SPG4, and the mechanisms by which spastin abnormalities lead to axonal degeneration in HSP. It is widely held that most, if not all, SPG4 mutations are pathogenic because of haploinsufficiency (ie, decreased abundance of functionally normal spastin) rather than a dominant negative mechanism.5-10 This conclusion is based on (1) the fact that many mutations reduce the abundance of full-length, sequence-normal spastin, such as mutations that cause premature translation termination, insertions, or deletions that lead to nonsense transcripts and mutations that cause aberrant messenger RNA splicing, and (2) recent studies in which expression of SPG4 bearing nonsense or frameshift mutations resulted in the absence of immunologically detectable spastin.11
SPG4 is expressed widely and undergoes alternate splicing variable inclusion of exon 4. Thus far, none of the more than 80 reported HSP-specific SPG4 mutations have occurred in exon 4. In addition to variable splicing, there is also evidence that tissue-specific posttranslational modification results in 75- and 80-kDa spastin isoforms.11 Charvin et al11 showed spastin was present in neurons, particularly in the brain, and also in anterior horn motor neurons, but not within glia. Spastin contains an ATPase associated with diverse cellular activities (AAA) domain.5 It also contains a nuclear localization signal,5 and very recent immunofluorescent studies indicate spastin is a nuclear protein. The intracellular location of spastin is controversial because previous studies indicated that spastin was distributed within the cytoplasm.12
Emerging evidence suggests that spastin may interact with microtubules. Azim et al13 showed that antitubulin antibodies could precipitate spastin in vitro. More recently, Errico et al11 showed that a spastin fusion protein colocalized with microtubules in Cos-7 and HeLa cells transfected with wild-type and mutant SPG4 expression vectors. Findings that spastin may interact directly with microtubules support the hypothesis that disturbances in axonal cytoskeleton or transport underlie some forms of HSP.14
Atlastin
Autosomal dominant HSP linked to the chromosome 14q SPG3A locus represents approximately 10% of dominantly inherited HSP cases15 and is particularly prevalent among those autosomal dominant HSP kindreds in which each affected subject developed symptoms in childhood.16 Zhao et al17 identified mutations in a novel gene (SPG3A) as the cause of this form of HSP. At this stage, insight into the possible function of SPG3A comes only from analysis of the sequence of its encoded protein, atlastin. Atlastin does not contain an AAA motif and is not homologous to spastin or other proteins implicated in HSP. In contrast, atlastin contains conserved motifs for GTPase binding and hydrolysis17 and is structurally homologous to guanylate binding protein 1. The functional importance of atlastin's GTPase motif is indicated by a recently identified HSP mutation that disrupted a conserved GTPase domain.18
Guanylate binding protein 1, to which atlastin shows homology, is a member of the dynamin family of large GTPases. Dynamins play essential roles in a wide variety of vesicle trafficking events.19-24 Dynamins play essential roles in the action of many neurotrophic factors and are critical elements in the rapid and efficient process of recycling of synaptic vesicles. Dynamins are also involved in the maintenance and distribution of mitochondria25 and, through their association with actin and microtubules, have been implicated in maintenance of the cytoskeleton.26 The important and diverse functions of dynamins raise many interesting possibilities by which atlastin mutations could cause axonal degeneration. These possibilities include defective synaptic vesicle recycling leading to abnormal synaptic structure and impaired neurotransmission, impaired activation of selected neurotrophic factors, and impaired mitochondrial distribution.
Kinesin Heavy Chain
Kinesin heavy chain (KIF5A) is a molecular motor that participates in the intracellular movement of organelles and macromolecules along microtubules in both anterograde and retrograde directions. KIF5A gene mutation was recently identified in affected subjects with HSP linked to the SPG10 locus.27 Subjects with KIF5A mutation exhibited either uncomplicated HSP or HSP associated with distal muscle atrophy.27 The HSP-specific KIF5A mutation disrupted an invariant asparagine residue that, when mutated in orthologous kinesin heavy chain motor proteins, prevented stimulation of the motor ATPase by microtubule binding.27 Finding KIF5A mutations in SPG10 HSP suggests that degeneration of distal axons in this and possibly of other forms of HSP may be related to disturbance of axonal transport.28
Heat Shock Protein 60 or Chaperonin 60
Mutation in the mitochondrial protein heat shock protein 60, also known as chaperonin 60, causes SPG13-linked autosomal dominant HSP. SPG13 HSP is an autosomal dominant form of uncomplicated HSP mapped to chromosome 2q24-34. Recently, Hansen et al29 identified a mutation in heat shock protein 60 in affected subjects from an SPG13-linked HSP kindred. The mechanism by which heat shock protein 60 mutations cause HSP are not yet known. It is intriguing however, that 2 HSP genes, heat shot protein 60 or chaperonin 60 and SPG7 or paraplegin, encode mitochondrial proteins.
NIPA1
NIPA1 gene mutations cause autosomal dominant HSP linked to chromosome 15q (SPG6 HSP). SPG6 HSP is a prototypical example of adolescent or adult-onset, slowly progressive, uncomplicated HSP. SPG6 and SPG8 are perhaps the most severe forms of dominantly inherited, uncomplicated HSP.30 Chai et al31 identified nonimprinted Prader-Willi/Angleman (NIPA) locus genes as candidate's for SPG6. Rainier et al32 identified a disease-specific mutation in a novel gene (NIPA1) in an SPG6-linked HSP kindred and in an unrelated kindred that was too small for linkage analysis. Precisely the same NIPA1 gene mutation (T45R) was discovered in 2 unrelated kindreds.32 The function of NIPA1 is unknown. It is widely expressed, particularly in the central nervous system. The presence of 9 alternating hydrophobic-hydrophilic domains suggests that NIPA1 encodes a membrane protein.32 This feature makes NIPA1 unique among HSP proteins. The NIPA1 mutation T45R appears to act through a "dominant negative" gain of function. This prediction is based on the observation that subjects who are missing one NIPA1 gene entirely (eg, subjects with Prader-Willi and Angleman syndromes who have deletions involving this region of chromosome 15q) do not develop HSP.
TWO AUTOSOMAL RECESSIVE HSP GENES
Paraplegin
SPG7 encodes a mitochondrial protein (paraplegin). De Michele et al33 discovered disease-specific mutations in SPG7 as the cause of chromosome 16q–linked autosomal recessive HSP. This is a rare form of autosomal recessive HSP with only a few reported families affected.33-34 Within these families, some individuals had pure HSP, and others had HSP complicated by dysarthria, dysphagia, optic disc pallor, axonal neuropathy, and evidence of vascular lesions, cerebellar atrophy, or cerebral atrophy on cranial magnetic resonance imaging. Paraplegin is highly homologous to the yeast mitochondrial ATPases AFG3, RCA1, and YME1, which have both proteolytic and chaperone-like activities at the inner mitochondrial membrane. Paraplegin is also localized to mitochondria.33 Muscle biopsy specimens from some, but not all, HSP patients with SPG7 gene mutations showed ragged-red and cytochrome-oxidase–negative fibers and abnormal mitochondrial structure typical of mitochondriopathy.33
SPG7 knockout mice exhibit signs of HSP. Ferreirinha et al35 reported preliminary studies in homozygous SPG7/paraplegin knockout mice. These animals displayed impaired performance on a rotorod apparatus that started at age 6 months and worsened with age. Histological analysis of the spinal cord showed axonal swelling, particularly in the lateral columns of the lumbar spinal cord, consistent with a retrograde axonopathy. The changes were progressive with signs of axonal degeneration becoming prominent at age 12 months.
Although 2 HSP genes (SPG7/paraplegin and SPG13/chaperonin 60) are mitochondrial proteins, it does not appear that all types of HSP are due to mitochondrial dysfunction. Biochemical and histological evidence of mitochondrial abnormalities has been sought but has not been observed in SPG4 (spastin), SPG3A (atlastin), SPG8, and SPG6 autosomal dominant HSP.5, 36-38
Spartin
Spartin mutations cause HSP associated with distal muscle wasting (SPG20 Troyer syndrome).39 This gene is designated "spartin" (spastin-related autosomal recessive Troyer protein) because its amino-terminal region is similar to that of spastin, mutations in which cause SPG4 HSP. Spartin is also homologous to proteins involved in endosome morphology and membrane trafficking.
TWO X-LINKED HSP GENES
Proteolipid Protein
Proteolipid protein (PLP) is an intrinsic myelin protein. PLP gene duplications and point mutations cause Pelizaeus-Merzbacher disease, an infantile-onset, progressive leukodystrophy, and are responsible for dysmyelination in jimpy mice.40-41 In addition, some individuals with X-linked HSP linked to the SPG2 locus on Xq22 also have PLP mutations.42-43 Although some of these patients have clinical features consistent with uncomplicated HSP, others have abnormal-appearing white matter on brain magnetic resonance imaging scans or evidence of peripheral neuropathy. Leukodystrophy is not a feature of other forms of uncomplicated HSP.
Some of the phenotypic variation of PLP mutation syndromes (infantile-onset leukodystrophy vs childhood-onset slowly progressive spastic paraparesis) can be attributed to different mutations in the PLP gene. However, both syndromes have occurred in the same family in individuals who share the same PLP gene mutation (F. Cambi, MD, PhD, J.K.F., unpublished observation, 2001). This observation indicates that, in some cases, the neurologic consequences of PLP gene mutation are influenced by modifying factors that presumably include additional genes and possibly environmental factors.
L1 Cell Adhesion Molecule
Neuronal cell adhesion molecule L1 (L1CAM) gene mutations cause a variety of X-linked neurologic disorders, including complicated spastic paraplegia, hydrocephalus, and mental retardation aphasia, shuffling gait, and adducted thumbs (MASA) syndrome.44 Although there is correlation between some of these syndromes and specific L1CAM mutations,45 X-linked hydrocephalus, MASA syndrome, and X-linked spastic paraplegia have occurred in kindreds in which affected individuals had the same L1CAM mutation.46 L1CAM is an integral membrane glycoprotein and a member of the immunoglobulin superfamily of cell adhesion molecules that mediate cell-to-cell attachment. L1CAM is found primarily in the nervous system, and its functions include guidance of neurite outgrowth during development, neuronal cell migration, and neuronal cell survival.47-48 Dahme et al49 used gene targeting to create transgenic mice in which the L1CAM gene was disrupted. These animals exhibited weak hind limbs and reduced size of corticospinal tracts.
CONCLUSIONS
The very recent discovery of many HSP genes is rapidly shaping new concepts of the pathophysiologic mechanisms of HSP. Whereas the uniform clinical appearance of uncomplicated HSPs initially suggested that a common biochemical disturbance underlies most types of HSP, this appears to not be the case. Rather, it appears that very long central nervous system axons (ie, corticospinal tracts and dorsal column fibers) are particularly vulnerable to a number of distinct biochemical disturbances and that the highly similar clinical features of genetically diverse types of uncomplicated HSP reflect the limited repertoire of symptoms from corticospinal tract and, to a lesser extent, dorsal column fiber disturbance.
Based on the diversity of the HSP genes discovered, a biochemical classification of HSP is emerging. For example, one can consider (1) HSP due to mitochondrial abnormality (including SPG13 due to chaperonin 60 mutation and SPG7 due to paraplegin mutation); (2) HSP due to axonal transport abnormality (including SPG10 due to kinesin heavy chain mutation and possibly SPG3A due to atlastin mutation and SPG4 due to spastin mutation; (3) HSP due to primary myelin disturbance (SPG2 due to PLP mutation); and (4) HSP due to embryonic development of corticospinal tract neurons (SPG1 due to L1CAM mutation). Whether these disparate primary biochemical disturbances converge into one or more common pathways remains to be determined. Each HSP gene discovery permits direct exploration of the molecular mechanisms that underlie HSP, insights that bring us one step closer to developing real treatment.
AUTHOR INFORMATION
Corresponding author and reprints: John K. Fink, MD, 5214 Cancer Geriatrics Center Bldg, Box 0940, 1500 E Medical Center Dr, Ann Arbor, MI 48109 (e-mail: jkfink{at}umich.edu).
Accepted for publication March 25, 2003.
This study was supported by grants R01NS33645, R01NS36177 and R01NS38713 from the National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Md, and grants from the Veterans Affairs Merit Review, Washington, DC, and the National Organization for Rare Disorders, Danbury, Conn.
I gratefully acknowledge the expert secretarial assistance of Lynette Girbach and the participation of subjects with HSP and their families, without whom our investigations of HSP would not be possible.
From the Department of Neurology, University of Michigan, and the Geriatric Research Education and Clinical Center, Ann Arbor Veterans Affairs Medical Center, Ann Arbor.
REFERENCES
1. Fink JK. Hereditary spastic paraplegia. In: Rimoin DL, Connor JM, Pyeritz R, Korf B, Emery AEH, eds. Emery & Rimoin's Principles and Practice of Medical Genetics. 4th ed. New York, NY: Churchill Livingstone; 2002:3124-3145.
2. Behan W, Maia M. Strumpell's familial spastic paraplegia: genetics and neuropathology. J Neurol Neurosurg Psychiatry. 1974;37:8-20.
FREE FULL TEXT
3. Hodgkinson CA, Bohlega S, Abu-Amero SN, et al. A novel form of autosomal recessive pure hereditary spastic paraplegia maps to chromosome 13q14. Neurology. 2002;59:1905-1909.
FREE FULL TEXT
4. Fink JK. Hereditary spastic paraplegia. In: Katirji B, Kaminsky HJ, Preston DC, Ruff RL, Shapiro BE, eds. Woburn, Mass: Butterworth-Heinemann; 2002:1290-1297.
5. Hazan J, Fonknechten N, Mavel D, et al. Spastin, a new AAA protein, is altered in the most frequent form of autosomal dominant spastic paraplegia. Nat Genet. 1999;23:296-303.
FULL TEXT
|
ISI
| PUBMED
6. Hentati A, Deng H-X, Zhai BA, et al. Novel mutations in spastin gene and absence of correlation with age at onset of symptoms. Neurology. 2000;55:1388-1390.
FREE FULL TEXT
7. Lindsey JC, Lusher ME, McDermott CJ, et al. Mutation analysis of the spastin gene (SPG4) in patients with hereditary spastic paraparesis. J Med Genet. 2000;37:759-765.
FREE FULL TEXT
8. Fonknechten N, Mavel D, Byrne P, et al. Spectrum of SPG4 mutations in autosomal dominant spastic paraplegia. Hum Mol Genet. 2000;9:637-644.
FREE FULL TEXT
9. Svenson IK, Ashley-Koch AE, Gaskell PC, et al. Identification and expression analysis of spastin gene mutations in hereditary spastic paraplegia. Am J Hum Genet. 2001;68:1077-1085.
FULL TEXT
|
ISI
| PUBMED
10. Wang J, Hennigan AN, Morini A, Ananth U, Seltzer WK. Molecular diagnostic testing for autosomal dominant hereditary spastic paraplegia: identification of novel mutations in the SPG4 gene [abstract]. Am J Hum Genet. 2002;71:386.
11. Charvin D, Fonknechten N, Cifuentes-Diaz C, et al. Mutations in SPG4 are responsible for a loss of function of spastin, an abundant neuronal protein localized to the nucleus [abstract]. Am J Hum Genet. 2002;71:516.
12. Errico A, Ballabio A, Rugarli E. Spastin, the protein mutated in autosomal dominant hereditary spastic paraplegia, is involved in microtubule dynamics. Hum Mol Genet. 2002;11:153-163.
FREE FULL TEXT
13. Azim AC, Hentati A, Haque MFU, Hirano M, Ouachi K, Siddique T. Spastin, a new AAA protein, binds to a and b tubulins [abstract]. Am J Hum Genet. 2000;67(suppl):197.
FULL TEXT
|
ISI
| PUBMED
14. Rainier S, Jones SM, Esposito C, Otterud B, Leppert M, Fink JK. Analysis of microtubule-associated protein 1a gene in hereditary spastic paraplegia. Neurology. 1998;51:1509-1510.
FREE FULL TEXT
15. Fink JK, Heiman-Patterson T, Bird T, et al. Hereditary spastic paraplegia: advances in genetic research. Neurology. 1996;46:1507-1514.
FREE FULL TEXT
16. Alvarado DM, Ming L, Hedera P, et al. Atlastin gene analysis in early onset hereditary spastic paraplegia [abstract]. Am J Hum Genet. 2001;69:597.
17. Zhao X, Alvarado D, Rainier S, et al. Mutations in a novel GTPase cause autosomal dominant hereditary spastic paraplegia. Nat Genet. 2001;29:326-331.
FULL TEXT
|
ISI
| PUBMED
18. Muglia M, Magariello A, Nicoletti G, et al. Further evidence that SPG3A gene mutations cause autosomal dominant hereditary spastic paraplegia. Ann Neurol. 2002;51:669-672.
FULL TEXT
|
ISI
| PUBMED
19. Zhang Y, Moheban DB, Conway BR, Bhattacharyya A, Segal RA. Cell surface Trk receptors mediate NGF-induced survival while internalized receptors regulate NGF-induced differentiation. J Neurosci. 2000;20:5671-5678.
FREE FULL TEXT
20. Nicoziani P, Vilhardt F, Llorente A, et al. Role for dynamin in late endosome dynamics and trafficking of the cation-independent mannose 6-phosphate receptor. Mol Biol Cell. 2000;11:481-495.
FREE FULL TEXT
21. Carroll RC, Beattie EC, Xia H, et al. Dynamin-dependent endocytosis of inotropic glutamate receptors. Proc Natl Acad Sci U S A. 1999;96:14112-14117.
FREE FULL TEXT
22. Della Rocca GJ, Mukhin YV, Garnovskaya MN, et al. Serotonin 5-HT1A receptor-mediated Erk activation requires calcium/calmodulin-dependent receptor endocytosis. J Biol Chem. 1999;274:4749-4753.
FREE FULL TEXT
23. Vogler O, Bogatkewitsch GS, Wriske C, Krummeneri P, Jakobs KH, van Kopopen CJ. Receptor subtype-specific regulation of muscarinic acetylcholine receptor sequestration by dynamin: distinct sequestration of m2 receptors. J Biol Chem. 1998;273:12155-12160.
FREE FULL TEXT
24. Jones SM, Howell KE, Henley JR, Cao H, McNiven MA. Role of dynamin in the formation of transport vesicles from the trans-Golgi network. Science. 1998;279:573-577.
FREE FULL TEXT
25. Pitts KR, Yoon Y, Krueger EW, McNiven MA. The dynamin-like protein DLP1 is essential for normal distribution and morphology of the endoplasmic reticulum and mitochondria in mammalian cells. Mol Biol Cell. 1999;10:4403-4417.
FREE FULL TEXT
26. Ochoa GC, Slepnev VI, Neff L, et al. A functional link between dynamin and the actin-cytoskeleton at podosomes. J Cell Biol. 2000;150:377-389.
FREE FULL TEXT
27. Pericak-Vance MA, Kloos MT, Reid E, et al. A kinesin heavy chain (K1F5A) mutation in hereditary spastic paraplegia (SPG10) [abstract]. Am J Hum Genet. 2002;71:165.
FULL TEXT
|
ISI
| PUBMED
28. Crosby AH, Proukakis C. Is the transportation highway the right road for hereditary spastic paraplegia? Am J Hum Genet. 2002;71:1009-1016.
FULL TEXT
|
ISI
| PUBMED
29. Hansen JJ, Durr A, Cournu-Rebeix I, et al. Hereditary spastic paraplegia SPG13 is associated with a mutation in the gene encoding the mitochondrial chaperonin Hsp60. Am J Hum Genet. 2002;70:1328-1332.
FULL TEXT
|
ISI
| PUBMED
30. Fink JK, Hedera P. Hereditary spastic paraplegia: genetic heterogeneity and genotype-phenotype correlation. Semin Neurol. 1999;19:301-310.
ISI
| PUBMED
31. Chai JH, Locke DP, Greally JM, et al. Identification of four highly conserved genes between breakpoint hotspots BP1 and BP2 of the Prader-Willi/Angelman syndromes deletion region that have undergone evolutionary transposition mediated by flanking duplicons. Am J Hum Genet. In press.
32. Rainier S, Chai JH, Tokarz D, Nicholls RD, Fink JK. NIPA1 gene mutations cause autosomal dominant hereditary spastic paraplegia (SPG6). Am J Hum Genet. In press.
33. De Michele G, De Fusco M, Cavalcanti F, et al. A new locus for autosomal recessive hereditary spastic paraplegia maps to chromosome 16q24.3. Am J Hum Genet. 1998;63:135-139.
FULL TEXT
|
ISI
| PUBMED
34. Pratt VM, Boyadjiev S, Dlouhy SR, Silver K, Der Kaloustian VM, Hodes ME. Pelizaeus-Merzbacher disease in a family of Portuguese origin caused by a point mutation in exon 5 of the proteolipid protein gene. Am J Med Genet. 1995;55:402-404.
FULL TEXT
|
ISI
| PUBMED
35. Ferreirinha F, Quattrini A, Valsecchi V, Errico A, Ballabio A, Rugarli EI. Mice lacking paraplegin, a mitochondrial AAA protease involved in hereditary spastin paraplegia, show axonal degeneration and abnormal mitochondria [abstract]. Am J Hum Genet. 2001;69(suppl):196.
36. Nance MA, Raabe WA, Midani H, et al. Clinical heterogeneity of familial spastic paraplegia linked to chromosome 2p21. Hum Hered. 1998;48:169-178.
FULL TEXT
|
ISI
| PUBMED
37. Hedera P, DiMauro S, Bonilla E, Wald J, Eldevik OP, Fink JK. Phenotypic analysis of autosomal dominant hereditary spastic paraplegia linked to chromosome 8q. Neurology. 1999;53:44-50.
FREE FULL TEXT
38. Zelnik N, Leshinsky E, Kolodny EH. Familial spastic paraparesis: is it mitochondrial disorder? Pediatr Neurosurg. 1995;23:225-226.
ISI
| PUBMED
39. Patel H, Cross H, Proukakis C, et al. SPG20 is mutated in Troyer syndrome, an hereditary spastic paraplegia. Nat Genet. 2002;31:347-348.
ISI
| PUBMED
40. Hudson LD, Berndt JA, Puckett C, Kozak CA, Lazzarini RA. Aberrant splicing of proteolipid protein mRNA in the demyelinating jimpy mutant mouse. Proc Natl Acad Sci U S A. 1987;84:1454-1458.
FREE FULL TEXT
41. Dautigny A, Mattei M-G, Morello D, et al. The structural gene coding for myelin-associated proteolipid protein is mutated in jimpy mice. Nature. 1986;321:867-869.
FULL TEXT
| PUBMED
42. Cambi F, Tartaglino L, Lublin FD, McCarren D. X-linked pure familial spastic paraparesis: characterization of a large kindred with magnetic resonance imaging studies. Arch Neurol. 1995;52:665-669.
FREE FULL TEXT
43. Dube M-P, Boutros M, Figlewicz DA, Rouleau GA. A new pure hereditary spastic paraplegia kindred maps to the proteolipid protein gene locus [abstract]. Am J Hum Genet. 1997;61:A169.
44. Fransen E, Vits L, VanCamp G, Willems PJ. The clinical spectrum of mutations in L1, a neuronal cell adhesion molecule. Am J Med Genet. 1996;64:73-77.
FULL TEXT
|
ISI
| PUBMED
45. Weller S, Gartner J. Genetic and clinical aspects of X-linked hydrocephalus (L1 disease): mutations in the L1CAM gene. Hum Mutat. 2001;18:1-12.
FULL TEXT
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ISI
| PUBMED
46. Fryns JP, Spaepen A, Cassiman JJ, van den Berghe H. X-linked complicated spastic paraplegia, MASA syndrome, and X-linked hydrocephaly owing to congenital stenosis of the aqueduct of Sylvius: a variable expression of the same mutation at Xq28. J Med Genet. 1991;28:429-431.
47. Kenwrick S, Watkins A, De Angelis E. Neural cell recognition molecule L1: relating biological complexity to human disease mutations. Hum Mol Genet. 2000;9:879-886.
FREE FULL TEXT
48. Bateman A, Jouet M, MacFarlane J, Du JS, Kenwrick S, Chothia C. Outline structure of the human L1 cell adhesion molecule and the sites where mutations cause neurological disorders. EMBO J. 1996;15:6050-6059.
ISI
| PUBMED
49. Dahme M, Bartsch U, Martini R, Anliker B, Schachner M, Mantei N. Disruption of the mouse L1 gene leads to malformations of the nervous system. Nat Genet. 1997;17:346-349.
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ISI
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Bohan and Azizi
Arch Neurol 2004;61:1470-1471.
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August 24 Highlight and Commentary
Neurology 2004;63:603-603.
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Incomplete penetrance in an SPG3A-linked family with a new mutation in the atlastin gene
D'Amico et al.
Neurology 2004;62:2138-2139.
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Hereditary Spastic Paraplegia: Spastin Phenotype and Function
Fink and Rainier
Arch Neurol 2004;61:830-833.
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A new SPG4 mutation in a variant form of spastic paraplegia with congenital arachnoid cysts
Orlacchio et al.
Neurology 2004;62:1875-1878.
ABSTRACT
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ARSACS goes global
Gomez
Neurology 2004;62:10-11.
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