Spg3a mutation screening in english families with early onset autosomal dominant hereditary spastic paraplegia. (2003 Nov)
spg3a mutation screening in english families with early onset autosomal dominant hereditary spastic paraplegia . mutations in the spg3a gene encoding the novel gtpase atlastin have recently been implicated in causing autosomal dominant hereditary spastic paraplegia ( adhsp ) in six unrelated families . The phenotype of affected individuals in all cases has been of an early onset uncomplicated form of the disease . One particular missense mutation , r239c , in exon 7 of spg3a has been identified in three of these families . We performed mutation screening by direct sequencing of all 14 exons and flanking sequences of the spg3a gene in affected individuals from 12 unrelated english families , all with an early onset uncomplicated adhsp in whom spastin mutations had previously been excluded . The r239c mutation was found to co segregate with the disease in one english adhsp family confirming a widespread prevalence for this commonly occurring mutation . No additional spg3a mutations were identified in the remaining 11 families suggesting that even within this specific sub set of early onset uncomplicated adhsp patients atlastin mutations are relatively rare .

A missense mutation in the coiled coil domain of the kif5a gene and late onset hereditary spastic paraplegia. (2006 Feb)
A missense mutation in the coiled coil domain of the kif5a gene and late onset hereditary spastic paraplegia . background : To our knowledge , up to now , only 2 mutations in the kif5a gene , a member of the kinesin superfamily , have been identified as the molecular cause of early onset autosomal dominant hereditary spastic paraparesis ( adhsp ) . objective : To assess the genetic defect in a family with late onset adhsp . patients AND methods : Only the proband agreed to undergo complete neurological testing and mutational analysis . The proband was screened for mutations in the spastin , atlastin , nipa1 , and kif5a genes , either by denaturing high performance liquid chromatography or sequence analysis . results : The history of the family was consistent with adhsp characterized by late onset of the disease . mutational analysis results were negative for the spastin , atlastin , and nipa1 genes but identified a missense mutation ( c . 1082c T ) in the coiled coil coding region of the kif5a gene . conclusions : This finding enlarges the phenotypic spectrum of adhsp linked to kif5a and enhances the role of that gene in the epidemiology of this disease . We propose that the kif5a gene should be routinely analyzed in patients with hereditary spastic paraplegia negative for spastin and atlastin mutations .

Neurophysiological findings in SPG4 patients differ from other types of spastic paraplegia. (2003 May)
neurophysiological findings in SPG4 patients differ from other types of spastic paraplegia . The authors examined 12 families with autosomal dominant hereditary spastic paraplegia for phenotypic characteristics predicting the underlying genotype . They found no clinical differences between patients with or without mutations in the spastin gene ( SPG4 ) . motor evoked potentials and nerve conduction studies were almost normal in those with SPG4 . In contrast , non SPG4 families had prolonged central motor conduction times or marked peripheral neuropathy , or both .

High frequency of partial spast deletions in autosomal dominant hereditary spastic paraplegia. (2006 Dec)
High frequency of partial spast deletions in autosomal dominant hereditary spastic paraplegia . background : hereditary spastic paraplegia ( HSP ) is a genetically heterogeneous neurodegenerative disease . The most frequent cause of autosomal dominant HSP is mutation of spast ( SPG4 locus ) , but additional pedigrees remain mutation negative by conventional screening despite linkage to SPG4 . objective : To determine the frequency of genomic copy number aberrations of spast in autosomal dominant HSP . methods : We developed and validated a multiplex ligation dependent probe amplification assay targeting spast and spg3a , another gene frequently involved in autosomal dominant HSP . In a multicenter study we subsequently investigated 65 index patients with autosomal dominant HSP , all of whom had previously been screened negative for spast mutations . independent secondary samples , additional family members , and cDNA were analyzed to confirm positive findings . results : aberrant MLPA profiles were identified in 12 cases ( 18 ) . They exclusively affect spast , represent deletions , segregate with the disease , and are largely pedigree specific . internal spast deletions entail expression of correspondingly shortened transcripts , which vary in stability . Age at onset in spast deletion carriers does not differ from that associated with other spast mutations . conclusions : partial spast deletions , but not spast amplifications and spg3a copy number aberrations , represent an underestimated cause of autosomal dominant hereditary spastic paraplegia . partial spast deletions are likely to act via haploinsufficiency …

Recent advances in hereditary spastic paraplegia. (2001 Jul)
recent advances in hereditary spastic paraplegia . The hereditary spastic paraplegias are a group of rare disorders that are characterized by great clinical and genetic heterogeneity . there has been an exponential increase in the number of HSP loci mapped in recent years , with nine out of the 17 loci reported during the past 2 years . eight loci have now been identified for the autosomal dominant form , and seven of these are associated with pure HSP . spastic paraplegia 4 remains the most frequent locus , and is usually associated with a pure phenotype . although the corresponding spastin gene was only recently identified , over 50 mutations have been described to date , which renders molecular diagnosis difficult . Five loci are known for autosomal recessive HSP , and four of these are associated with complex forms , all with different phenotypes . Two genes have been identified : paraplegin and sacsin . finally , three loci have been identified in X linked HSP , two of which are complex forms . The genes that encode L1 and PLP were the first to be identified in HSP disorders . surprisingly , the five genes encode proteins of different families , making understanding and diagnosis of HSP even more difficult . The discovery of new genes should hopefully help to clarify the pathophysiology of these disorders .

The hereditary spastic paraplegia gene , spastin , regulates microtubule stability to modulate synaptic structure and function. (2004 Jul)
The hereditary spastic paraplegia gene , spastin , regulates microtubule stability to modulate synaptic structure and function . background : hereditary spastic paraplegia ( HSP ) is a devastating neurological disease causing spastic weakness of the lower extremities and eventual axonal degeneration . Over 20 genes have been linked to HSP in humans ; however , mutations in one gene , spastin ( SPG4 ) , are the cause of 40 of all cases . spastin is a member of the atpases associated with diverse cellular activities ( AAA ) protein family , and contains a microtubule interacting and organelle transport ( MIT ) domain . previous work in cell culture has proposed a role for spastin in regulating microtubules . results : employing drosophila transgenic methods for overexpression and RNA interference ( RNAi ) , we have investigated the role of spastin in vivo . We show that drosophila spastin ( D spastin ) is enriched in axons and synaptic connections . At neuromuscular junctions ( NMJ ) , dspastin RNAi causes morphological undergrowth and reduced synaptic area . moreover , dspastin overexpression reduces synaptic strength , whereas dspastin RNAi elevates synaptic currents . By using antibodies against posttranslationally modified alpha tubulin , we find that dspastin regulates microtubule stability . functional synaptic defects caused by dspastin RNAi and overexpression were pharmacologically alleviated by agents that destabilize and stabilize microtubules , respectively . conclusions : Loss of dspastin in drosophila causes an aberrantly stabilized microtubule cytoskeleton in neurons and …

Spastin , a new AAA protein , is altered in the most frequent form of autosomal dominant spastic paraplegia. (1999 Dec)
spastin , a new AAA protein , is altered in the most frequent form of autosomal dominant spastic paraplegia . autosomal dominant hereditary spastic paraplegia ( AD HSP ) is a genetically heterogeneous neurodegenerative disorder characterized by progressive spasticity of the lower limbs . among the four loci causing AD HSP identified so far , the SPG4 locus at chromosome 2p2 1p22 has been shown to account for 40 50 of all AD HSP families . using a positional cloning strategy based on obtaining sequence of the entire SPG4 interval , we identified a candidate gene encoding a new member of the AAA protein family , which we named spastin . sequence analysis of this gene in seven SPG4 linked pedigrees revealed several DNA modifications , including missense , nonsense and splice site mutations . Both SPG4 and its mouse orthologue were shown to be expressed early and ubiquitously in fetal and adult tissues . The sequence homologies and putative subcellular localization of spastin suggest that this atpase is involved in the assembly or function of nuclear protein complexes .

Paraplegin gene analysis in hereditary spastic paraparesis ( HSP ) pedigrees in northeast england. (2001 Mar)
paraplegin gene analysis in hereditary spastic paraparesis ( HSP ) pedigrees in northeast england . objective : To identify the frequency and characterize the phenotype of paraplegin mutations in the hereditary spastic paraparesis ( HSP ) population in the northeast of england . background : HSP is a disorder that shows both clinical and genetic heterogeneity . To date , 13 loci have been associated with an HSP phenotype , with the causative gene having been identified in four of these . Two autosomal genes have been identified , paraplegin and spastin , and two X linked genes have been identified , l1cam ( cell adhesion molecule ) and proteolipid protein . methods : thirty HSP pedigrees from the northeast of england were analyzed for mutation in each of the 17 exons of the paraplegin gene . results : A single family with a paraplegin mutation was identified in which the paraplegin mutation co segregates with an HSP phenotype in an apparent dominant manner . The authors also describe frequent polymorphism in the paraplegin gene in both the HSP and control populations . conclusion : mutations in the paraplegin gene are not a common cause of HSP in the northeast of england . The phenotype of the paraplegin related HSP family described had several striking features including amyotrophy , raised creatine kinase , sensorimotor peripheral neuropathy , and oxidative phosphorylation defect on muscle biopsy .

Knot / collier and cut control different aspects of dendrite cytoskeleton and synergize to define final arbor shape. (2007 Dec)
Knot / collier and cut control different aspects of dendrite cytoskeleton and synergize to define final arbor shape . In a complex nervous system , neuronal functional diversity is reflected in the wide variety of dendritic arbor shapes . different neuronal classes are defined by class specific transcription factor combinatorial codes . We show that the combination of the transcription factors Knot and Cut is particular to drosophila class IV dendritic arborization ( da ) neurons . Knot and Cut control different aspects of the dendrite cytoskeleton , promoting microtubule and actin based dendritic arbors , respectively . Knot delineates class IV arbor morphology by simultaneously synergizing with Cut to promote complexity and repressing Cut mediated promotion of dendritic filopodia / spikes . Knot increases dendritic arbor outgrowth through promoting the expression of spastin , a microtubule severing protein disrupted in autosomal dominant hereditary spastic paraplegia ( AD HSP ) . Knot and Cut may modulate cellular mechanisms that are conserved between drosophila and vertebrates . hence , this study gives significant general insight into how multiple transcription factors combine to control class specific dendritic arbor morphology through controlling different aspects of the cytoskeleton .

Mutations of SPG4 are responsible for a loss of function of spastin , an abundant neuronal protein localized in the … (2002 Dec)
mutations of SPG4 are responsible for a loss of function of spastin , an abundant neuronal protein localized in the nucleus . mutations of spastin are responsible for the most common autosomal dominant form of hereditary spastic paraplegia ( AD HSP ) , a disease characterized by axonal degeneration of corticospinal tracts and posterior columns . generation of polyclonal antibodies specific to spastin has revealed two isoforms of 75 and 80 kDa in both human and mouse tissues with a tissue specific variability of the isoform ratio . spastin is an abundant protein in neural tissues and immunolabeling experiments have shown that spastin is expressed in neurons but not in glial cells . these data indicate that axonal degeneration linked to spastin mutations is caused by a primary defect of neurons . protein and transcript analyses of patients carrying either nonsense or frameshift spastin mutations revealed neither truncated protein nor mutated transcripts , providing evidence that these mutations are responsible for a loss of spastin function . identifying agents able to induce the expression of the non mutated spastin allele should represent an attractive therapeutic strategy in this disease .

A de novo spast mutation leading to somatic mosaicism is associated with a later age at onset in HSP. (2007 Jul)
A de novo spast mutation leading to somatic mosaicism is associated with a later age at onset in HSP . SPG4 / spast , the gene encoding spastin , is responsible for the most frequent form of autosomal dominant hereditary spastic paraplegia ( HSP ) . SPG4 HSP is a heterogeneous disorder characterized by both interfamilial and intrafamilial variation , especially regarding the severity and the age at onset . In this study , we investigated the origin of the mutation and the factors involved in intra familial heterogeneity in a family with a SPG4 mutation . We demonstrated that the mutation occurred de novo and show evidence of somatic mosaicism in the grandfather , who was the only affected member of six siblings . His disease began at age 55 , much later than in his daughter , who had onset at age 18 , and his grandson , in whom onset was at age 5 . these observations indicate that de novo mutations can occur in SPG4 , and that somatic mosaicism might account for intra familial variation in SPG4 linked HSP .

Three novel spastin ( SPG4 ) mutations in families with autosomal dominant hereditary spastic paraplegia. (2002 Aug)
three novel spastin ( SPG4 ) mutations in families with autosomal dominant hereditary spastic paraplegia . hereditary spastic paraplegia ( HSP ) is a clinically and genetically heterogeneous condition , characterised principally by progressive spasticity of the lower limbs . forty percent of autosomal dominant ( AD ) pedigrees show linkage to the SPG4 locus on chromosome 2 , which encodes spastin , an atpase associated with diverse cellular activities ( AAA ) protein . We have performed a clinical and genetic study of three AD HSP families linked to SPG4 . sequencing revealed three novel causative mutations . Two of the mutations were located in exon 5 ( a 1 base pair ( bp ) insertion and a 5 bp deletion ) , resulting in frameshift and premature termination of translation , with the predicted protein lacking the entire AAA functional domain . The 5 bp deletion was associated with a later onset and mild cerebellar features . The third mutation was a 3 bp deletion in exon 9 , resulting in the loss of a highly conserved phenylalanine residue within the AAA cassette and an apparently milder phenotype . This is the first example of a deletion of an amino acid in spastin .

Novel spastin mutations and their expression analysis in two italian families. (2003 Aug)
novel spastin mutations and their expression analysis in two italian families . mutations in spastin cause the most common form of pure autosomal dominant hereditary spastic paraparesis ( SPG4 ) . Here , we report two italian families affected with SPG4 linked HSP harboring two novel spastin mutations . SSCP / sequencing analysis of the spastin gene showed a single base pair deletion causing a frame shift in one family ( 1442delt ) and a missense mutation ( 1726t C ) resulting in a leucine to proline amino acid change ( l534p ) in the other family . total RNA from the mutant and the wild type spastin allele in muscle biopsies from patients from the two affected families was quantitated . RNA expression was almost absent from the spastin allele harboring the single base pair deletion , while it was nearly normal for the spastin allele harboring the missense mutation . these data suggest that varying spastin RNA levels are found in out of frame and missense spastin mutations and imply different mechanisms involved in the molecular pathology of SPG4 linked HSP .

Hereditary spastic paraplegia : clinical genetic study of 15 families. (2004 Jun)
hereditary spastic paraplegia : clinical genetic study of 15 families . background : autosomal dominant hereditary spastic paraplegia ( adhsp ) is mainly caused by mutations in the SPG4 gene , which encodes a new member of the AAA ( adenosine triphosphatases associated with diverse cellular activities ) protein family ( spastin ) . accumulation of genotype phenotype correlation is important for better understanding of SPG4 linked hereditary spastic paraplegia . objectives : To perform a clinical and genetic study of families with adhsp and to perform the functional analysis of the founder mutation discovered in the SPG4 gene . design : genetic and clinical study . patients fifteen unrelated families with adhsp originating from southern scotland . MAIN outcome measures : clinical assessment , linkage analysis , haplotype study , expression of mutant spastin protein in cultured cells . results : Nine families with adhsp were linked to the SPG4 locus at 2p21 p24 . sequence analysis of spg4showed a novel n386s mutation in all 9 of these families . expression of mutant spastin showed aberrant distribution in cultured cells . haplotype analysis suggested the existence of a common founder . clinical examination of the affected members carrying the mutation showed phenotypic variations including broad range of age at onset and disease duration and additional neurologic features such as mental retardation . magnetic resonance imaging demonstrated unique features , including thin corpus callosum and atrophy of the cerebellum in 2 patients . linkage and sequence analyses showed no evidence …

The cellular and molecular pathology of the motor system in hereditary spastic paraparesis due to mutation of the spastin gene. (2003 Dec)
The cellular and molecular pathology of the motor system in hereditary spastic paraparesis due to mutation of the spastin gene . hereditary spastic paraparesis ( HSP ) is a genetically heterogeneous disorder , the most common cause of which is mutation of the spastin gene . recent evidence suggests a role for spastin in microtubule dynamics , but the distribution of the protein within the CNS is unknown . The core neuropathology of HSP is distal degeneration of the lateral corticospinal tract and of fasciculus gracilis , but there are few neuropathological studies of cases with a defined mutation . We aimed to determine the distribution of spastin expression in the human CNS and to investigate the cellular pathology of the motor system in HSP due to mutation of the spastin gene . using an antibody to spastin , we have carried out immunohistochemistry on postmortem brain . We have demonstrated that spastin is a neuronal protein . It is widely expressed in the CNS so that the selectivity of the degeneration in HSP is not due to the normal cellular distribution of the protein . We have identified mutation of the spastin gene in 3 autopsy cases of HSP . distal degeneration of long tracts in the spinal cord , consistent with a dying back axonopathy , was accompanied by a microglial reaction . The presence of novel hyaline inclusions in anterior horn cells and an alteration in immunostaining for cytoskeletal proteins and mitochondria indicates that long tract degeneration …

Spectrum of SPG4 mutations in a large collection of north american families with hereditary spastic paraplegia. (2002 Feb)
spectrum of SPG4 mutations in a large collection of north american families with hereditary spastic paraplegia . background : hereditary spastic paraplegia ( HSP ) is a neurodegenerative disease characterized by progressive spasticity and weakness of the lower limbs . The most common form of HSP is caused by mutations in the SPG4 gene , which codes for spastin , an adenosine triphosphatase with various cellular activities ( AAA ) protein family member . objective : To investigate a large collection of predominantly north american patients with HSP for mutations in the spastin encoding gene , SPG4 . methods : DNA from 76 unrelated affected individuals was studied for mutations by single stranded conformational polymorphism analysis and direct sequencing . Each new variant identified was then analyzed in 80 control subjects to determine whether the variant is a common polymorphism or a rare mutation . All DNA samples were amplified by polymerase chain reaction , followed by electrophoresis and autoradiography . results : We identified 8 novel mutations and 5 previously reported mutations in 15 affected individuals . The novel mutations are 4 missense , 1 nonsense , 1 frameshift , and 2 splice mutations . Two polymorphisms ( one in an affected individual ) were also identified . conclusions : Our collection of families with HSP is different on a genetic level from those previously described . The percentage of our families with a SPG4 mutation is 10 lower than the 40 estimate of families with autosomal dominant HSP …

Identification of the drosophila melanogaster homolog of the human spastin gene. (2003 Aug)
identification of the drosophila melanogaster homolog of the human spastin gene . The human SPG4 locus encodes the spastin gene , which is responsible for the most prevalent form of autosomal dominant hereditary spastic paraplegia ( AD HSP ) , a neurodegenerative disorder . Here we identify the predicted gene product cg5977 as the drosophila homolog of the human spastin gene , with much higher sequence similarities than any other related AAA domain protein in the fly . furthermore we report a new potential transmembrane domain in the N terminus of the two homologous proteins . during embryogenesis , the expression pattern of drosophila spastin becomes restricted primarily to the central nervous system , in contrast to the ubiquitous expression of the vertebrate spastin genes . given this nervous system specific expression , it will be important to determine if drosophila spastin loss of function mutations also lead to neurodegeneration .

Identification of a novel mutation in the spastin gene ( SPG4 ) in an italian family with hereditary spastic paresis. (2006 Nov)
identification of a novel mutation in the spastin gene ( SPG4 ) in an italian family with hereditary spastic paresis . hereditary spastic paraparesis ( HSP ) includes a heterogeneous group of neurodegenerative diseases characterised by progressive spasticity and hyper reflexia of the lower limbs . autosomal dominant HSP type 4 is the most common clinical form , accounting for about 40 50 of autosomal dominant HSP families . This form is due to mutation of the gene encoding spastin ( SPG4 ) , an ATP ase associated with a variety of cellular function ( AAA ) . Here we describe a novel missense mutation ( 1297t C ; 391L P ) in exon 8 of SPG4 gene , identified in 2 members ( mother and son ) of an italian family with autosomal dominant HSP , clinically pure in the mother and complicated in the son . The mutation lies in a highly conserved AAA box domain between amino acids 342 and 599 in spastin sequence . In both patients , this novel mutation was associated with the absence of relatively common clinical characteristics , such as vibratory sensory deficit and loss of sphincter control , and partial temporal epilepsy , particularly in the son , with infantile onset , secondarily generalised and moderately severe neuropsychiatric symptoms .

Subcellular localization of spastin : implications for the pathogenesis of hereditary spastic paraplegia. (2005 Oct)
subcellular localization of spastin : implications for the pathogenesis of hereditary spastic paraplegia . hereditary spastic paraplegia ( HSP ) is a group of clinically and genetically heterogeneous diseases characterized by neuronal degeneration that is maximal at the distal ends of the longest axons of the central nervous system . The most common cause of autosomal dominant HSP is mutation of a novel gene encoding spastin , a protein whose function is still being elucidated . One clue concerning spastin function is its intracellular localization . Here , we describe a novel anti spastin antiserum designed to a unique epitope contained within all splicing isoforms . The antiserum exhibits specific immunostaining of recombinant spastin in intact , fixed cells . using this reagent , we find that endogenous spastin is located at the centrosome in a variety of cell types at all points in the cell cycle . This localization is resistant to microtubule disruption , suggesting that spastin may be an integral centrosomal protein . In addition to the centrosome , spastin also localizes at discrete focal regions along the axons of primary cultured neurons . these data lend additional support to the emerging hypothesis that spastin plays a role in microtubule dynamics , with a crucial role in microtubule organization .

Disease related phenotypes in a drosophila model of hereditary spastic paraplegia are ameliorated by treatment with vinblastine. (2005 Nov)
disease related phenotypes in a drosophila model of hereditary spastic paraplegia are ameliorated by treatment with vinblastine . hereditary spastic paraplegias ( HSPs ) are a group of neurodegenerative diseases characterized by progressive weakness and spasticity of the lower limbs . dominant mutations in the human SPG4 gene , encoding spastin , are responsible for the most frequent form of HSP . spastin is an atpase that binds microtubules and localizes to the spindle pole and distal axon in mammalian cell lines . furthermore , its drosophila homolog , drosophila spastin ( dspastin ) , has been recently shown to regulate microtubule stability and synaptic function at the drosophila larval neuromuscular junction . Here we report the generation of a spastin linked HSP animal model and show that in drosophila , neural knockdown of dspastin and , conversely , neural overexpression of dspastin containing a conserved pathogenic mutation both recapitulate some phenotypic aspects of the human disease , including adult onset , locomotor impairment , and neurodegeneration . At the subcellular level , neuronal expression of both dspastin RNA interference and mutant dspastin cause an excessive stabilization of microtubules in the neuromuscular junction synapse . In addition , we provide evidence that administration of the microtubule targeting drug vinblastine significantly attenuates these phenotypes in vivo . Our findings demonstrate that loss of spastin function elicits HSP like phenotypes in drosophila , provide novel insights into the molecular mechanism of spastin mutations , and raise the possibility that therapy with vinca …