Spastin related hereditary spastic paraplegia with dysplastic corpus callosum

Thin corpus callosum has been recently observed in two patients with an autosomal dominant trait of hereditary spastic paraplegia (HSP) linked to a novel mutation in the spastin gene (SPG4). In the same two patients cerebellar atrophy has been found. Reportedly, in other members of the same family, there has been a variable presence of mental retardation. We report on the clinical and genetic investigation of an Austrian family with a novel mutation in the spastin gene. Genetic analysis of the SPG4 locus revealed a mutation (C1120A) and a known intronic polymorphism (996-47G>A) of the spastin gene. In one affected family member, previously undescribed dysplasia of the corpus callosum (CC) was found in conjunction with otherwise uncomplicated HSP. Dysplastic CC was not paralleled with cortical atrophy, cognitive impairment or other phenotypic variations. Two further affected family members showed the same mutation and polymorphism, but no evidence of CC abnormalities. We conclude that apparently pure HSP may present with MRI features of dysplastic CC. This finding extended the spastin-related phenotype which is distinct from previous reports of thin CC in HSP.     

Novel spastin (SPG4) mutations in Italian patients with hereditary spastic paraplegia

Spastic paraplegia type 4 is caused by mutations in the gene that encodes spastin (SPG4), a member of the AAA protein family. A cohort of 34 unrelated Italian patients with pure spastic paraplegia, of which 18 displayed autosomal dominant inheritance and 16 were apparently sporadic, were screened for mutations in the SPG4 gene by denaturing high performance liquid chromatography. We identified a previously reported mutation in a sporadic patient with pure hereditary spastic paraplegia. We also identified eight unrelated patients with pure autosomal dominant hereditary spastic paraplegia carrying five novel mutations in the SPG4 gene (one missense mutation, c.1304 C>T; one nonsense mutation, c.807C>A; two frameshift mutations, c.1281dupT, c.1514_1515insATA; and one splicing mutation, c.1322-2A>C). The frequency for SPG4 mutations detected in autosomal dominant hereditary spastic paraplegia was 44.4%. This study contributes to expand the spectrum of SPG4 mutations in Italian population.     

遗传性痉挛性截瘫一家系的临床特点与spastin基因突变分析

目的　探讨常染色体显性遗传的遗传性痉挛性截瘫 (SPG)一家系的临床特点,并行spastin基因突变分析。方法　对整个家系进行详细的临床检查,先证者和另一例家系内患者进行了心肌酶学、头颅核磁共振成像(MRI)、胸髓MRI、肌电图、体感诱发电位检查。应用聚合酶链式反应 单链构象多态性(PCR SSCP)结合DNA序列分析方法,检测该家系中所有 5例患者和 4名有血缘关系的健康人及家系外 50名无血缘关系健康对照者spastin基因的突变情况。结果　先证者和家系内另一例SPG患者胸髓MRI显示胸髓萎缩;PCR SSCP检测发现家系内患者均出现异常SSCP电泳带,经测序证实为Leu378Gln突变。结论　该常染色体显性遗传SPG家系的患者具有典型的临床表现,为spastin基因Leu378Gln突变所致。     

Novel mutation in the SPG3A gene in an African American family with an early onset of hereditary spastic paraplegia

BACKGROUND: Mutations in a novel GTPase gene SPG3A cause an autosomal dominant hereditary spastic paraplegia linked to chromosome 14q (SPG3), which accounts for approximately 10% to 15% of all autosomal dominant hereditary spastic paraplegia cases. The mutational spectrum of the SPG3A gene and the phenotype/genotype correlations have not yet been established. OBJECTIVE: To describe a kindred with an infantile onset of hereditary spastic paraplegia caused by a novel mutation in the SPG3A gene. PATIENTS: Complete neurological examination and genetic analysis were performed on 6 affected members of a small African American kindred. Linkage analysis to genetic markers near autosomal dominant hereditary spastic paraplegia loci on chromosomes 2p and 14q was performed. The coding sequence of the SPG3A gene was analyzed, and the identified change in the sequence was tested for being a benign polymorphism by sequencing 200 chromosomes from normal controls. RESULTS: Every affected individual had signs of uncomplicated spastic paraparesis without additional neurological abnormalities. None of the affected family members had ever walked normally. The history was consistent with an infantile onset, despite the normal acquisition of motor milestones. Genetic analysis suggested linkage to the SPG3A locus on chromosome 14q. Analysis of the SPG3A gene revealed a missense mutation C635T, predicted to result in a threonine to isoleucine substitution at codon 156. Analysis of 200 normal chromosomes did not identify the same change in healthy subjects. CONCLUSION: We report a novel mutation in the SPG3A gene in an African American family with an infantile onset of autosomal dominant hereditary spastic paraplegia.     

Complicated hereditary spastic paraplegia with thin corpus callosum (HSP-TCC) and childhood onset

The hereditary spastic paraplegias (HSPs) are a group of rare disorders with the predominant clinical feature of progressive spastic paraplegia. They are subdivided into pure and complicated forms according to whether the disorder is associated with other neurological abnormalities. We report on two unrelated female Caucasian patients with complicated HSP, aged 16 and 24 years, who showed progressive gait disturbance with spasticity and ataxia as well as cognitive impairment. Onset of symptoms was at age 3 and 10 years, respectively. MRI revealed mild diffuse non-progressive T (2)-signal alterations of cerebral white matter and thinning of the body and genu of the corpus callosum. Some similarity of clinical symptoms and MRI patterns with the phenotype of Mast syndrome prompted a mutation analysis of the SPG21 gene, encoding maspardin, which revealed a wild-type sequence in both patients. Clinical and neuroradiological features in our patients are diagnostic for complicated autosomal recessive hereditary spastic paraplegia with thin corpus callosum (HSP-TCC, SPG11). This disorder, characterized by a typical MRI pattern and a progressive spastic paraplegia that may be associated with dementia and ataxia, may have an onset in early childhood and probably is one of the more common forms of complicated HSP.     

Three novel mutations of the spastin gene in Chinese patients with hereditary spastic paraplegia

BACKGROUND: Hereditary spastic paraplegia is a group of genetically heterogeneous neurodegenerative disorders characterized by progressive spasticity of the lower limbs. The most common form of hereditary spastic paraplegia is caused by mutations in the spastin gene (SPG4), which encodes spastin, an adenosine triphosphatase associated with various cellular activities protein. OBJECTIVE: To investigate the Chinese patients with hereditary spastic paraplegia for mutations in SPG4. METHODS: DNA samples from 31 unrelated patients were analyzed for mutations in SPG4 by single-strand conformation polymorphism analysis and direct sequencing. All DNA samples were screened for mutations by the polymerase chain reaction, followed by electrophoresis and silver staining. Each new variant identified was analyzed in 50 control subjects to determine whether it is a polymorphism or a mutation. RESULTS: Three novel mutations were detected in 4 affected individuals, including 2 missense mutations (T1258A and A1293G) and 1 deletion mutation (1668-1670delCTA). CONCLUSIONS: To our knowledge, this is the first report of SPG4 mutations in the People's Republic of China. The percentage of involved Chinese families with autosomal dominant hereditary spastic paraplegia with an SPG4 mutation is 18% (4/22), lower than the estimated 40% linked to this locus.     

A large Japanese SPG4 family with a novel insertion mutation of the SPG4 gene: a clinical and genetic study

We studied a large Japanese family with autosomal dominant pure hereditary spastic paraplegia (ADPHSP) clinically and genetically. To date, seven loci causing ADPHSP have been mapped to chromosomes 14q, 2p, 15q, 8q, 12q, 2q, and 19q. Among these loci, the SPG4 locus on chromosome 2p21--p22 has been shown to account for approximately 40% of all autosomal dominant hereditary spastic paraplegia (ADHSP) families. Very recently, Hazan et al. identified the SPG4 gene encoding a new member of the AAA (ATPases associated with diverse cellular activities) protein family, named spastin. We found a novel insertion mutation (nt1272--1273insA) in exon 8 of the SPG4 gene in the present family. Our study is the first to confirm the causative mutation of the SPG4 gene in Japanese. Clinically, it is noteworthy that the disease progression in the patients of this family was slow in spite of the late onset, and more than half of the patients showed severe constipation in addition to pure spastic paraplegia.     

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.     

Spastic paraplegia, ataxia, mental retardation (SPAR): a novel genetic disorder

OBJECTIVE: To describe a kindred with a dominantly inherited neurologic disorder manifested either as uncomplicated spastic paraplegia or ataxia, spastic paraplegia, and mental retardation. METHODS: Neurologic examinations and molecular genetic analysis (exclusion of known SCA and HSP genes and loci; and trinucleotide repeat expansion detection [RED]) were performed in six affected and four unaffected subjects in this family. MRI, electromyography (EMG), and nerve conduction studies were performed in three affected subjects. RESULTS: The phenotype of this dominantly inherited syndrome varied in succeeding generations. Pure spastic paraplegia was present in the earliest generation; subsequent generations had ataxia and mental retardation. MRI showed marked atrophy of the spinal cord in all patients and cerebellar atrophy in those with ataxia. Laboratory analysis showed that the disorder was not caused by mutations in genes that cause SCA-1, SCA-2, SCA-3, SCA-6, SCA-7, SCA-8, and SCA-12; not linked to other known loci for autosomal dominant ataxia (SCA-4, SCA-5, SCA-10, SCA-11, SCA-13, SCA-14, and SCA-16); and not linked to known loci for autosomal dominant hereditary spastic paraplegia (HSP) (SPG-3, SPG-4, SPG-6, SPG-8, SPG-9, SPG-10, SPG-12, and SPG-13) or autosomal recessive HSP SPG-7. Analysis of intergenerational differences in age at onset of symptoms suggests genetic anticipation. Using RED, the authors did not detect expanded CAG, CCT, TGG, or CGT repeats that segregate with the disease. CONCLUSIONS: The authors describe an unusual, dominantly inherited neurologic disorder in which the phenotype (pure spastic paraplegia or spastic ataxia with variable mental retardation) differed in subsequent generations. The molecular explanation for apparent genetic anticipation does not appear to involve trinucleotide repeat expansion.     

A large family with hereditary spastic paraparesis due to a frame shift mutation of the spastin (SPG4) gene: association with multiple sclerosis in two affected siblings and epilepsy in other affected family members

Hereditary spastic paraparesis (HSP) is a clinically and genetically heterogeneous neurodegenerative disorder characterised by progressive lower limb spasticity and weakness. Some forms have been associated with white matter lesions and complex phenotypes. This study was prompted by the diagnosis of multiple sclerosis (MS) in two sisters from a large pedigree with hereditary spastic paraparesis. Twelve affected members of the extended family were examined (MRI and EEG were carried out and evoked potentials measured in five), and historical information was obtained from six affected deceased persons. The inherited disease phenotype was confirmed as autosomal dominant hereditary spastic paraparesis associated with epilepsy in four affected persons. None of the extended family had evidence of MS. Genetic analysis of the family has shown linkage to chromosome 2p and sequencing of the spastin gene has identified a 1406delT frameshift mutation in exon 10. This kindred demonstrates the clinical heterogeneity of HSP associated with spastin mutations. The possible relevance of the concurrence of HSP and MS in the sib pair is discussed.     

Motor system abnormalities in hereditary spastic paraparesis type 4 (SPG4) depend on the type of mutation in the spastin gene

BACKGROUND: Hereditary spastic paraparesis (HSP) denotes a group of inherited neurological disorders with progressive lower limb spasticity as their clinical hallmark; a large proportion of autosomal dominant HSP belongs to HSP type 4, which has been linked to the SPG4 locus on chromosome 2. A variety of mutations have been identified within the SPG4 gene product, spastin. OBJECTIVE: Correlation of genotype and electrophysiological phenotype. MATERIAL: Two large families with HSP linked to the SPG4 locus with a very similar disease with respect to age of onset, progression, and severity of symptoms. METHODS: Mutation analysis was performed by PCR from genomic DNA and cDNA, and direct sequencing. The motor system was evaluated using transcranial magnetic stimulation. RESULTS: Patients differ in several categories depending on the type of mutation present. CONCLUSIONS: For the first time in hereditary spastic paraparesis, a phenotypic correlate of a given genetic change in the spastin gene has been shown.     

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.     

Thinning of the Corpus Callosum and Cerebellar Atrophy is Correlated with Phenotypic Severity in a Family with Spastic Paraplegia Type 11

Background

Mutations in the spatacsin gene are associated with spastic paraplegia type 11 (SPG11), which is the most-common cause of autosomal recessive hereditary spastic paraplegia. Although SPG11 has diverse phenotypes, thinning of the corpus callosum is an important feature.

Case Report

Clinical, genetic, and radiological evaluations were undertaken in a large family from Gujarat in North India with hereditary spastic paraplegia, whose affected members presented with varying degrees of spasticity, ataxia, and cognitive impairment. The clinical severity and the degree of corpus callosum and cerebellar atrophy varied among the four affected individuals in the family. Genetic testing of the affected members revealed recessive mutations in the spatacsin gene, consistent with a diagnosis of SPG11.

Conclusions

We believe that the extent of corpus callosum thinning and cerebellar atrophy is correlated with disease severity in affected patients. The addition of extrapyramidal features in the most-affected members suggests that SPG11 exhibits considerable phenotypic heterogeneity.     

Complex phenotype in an Italian family with a novel mutation in SPG3A

Mutations in the SPG3A gene represent a significant cause of autosomal dominant hereditary spastic paraplegia with early onset and pure phenotype. We describe an Italian family manifesting a complex phenotype, characterized by cerebellar involvement in the proband and amyotrophic lateral sclerosis-like syndrome in her father, in association with a new mutation in SPG3A. Our findings further widen the notion of clinical heterogeneity in SPG3A mutations.     

Novel mutations in spastin gene and absence of correlation with age at onset of symptoms

Autosomal dominant hereditary spastic paraplegia is genetically heterogeneous, with at least five loci identified by linkage analysis. Recently, mutations in spastin were identified in SPG4, the most common locus for dominant hereditary spastic paraplegia that was previously mapped to chromosome 2p22. We identified five novel mutations in the spastin gene in five families with SPG4 mutations from North America and Tunisia and showed the absence of correlation between the predicted mutant spastin protein and age at onset of symptoms.     

SPG3A is the most frequent cause of hereditary spastic paraplegia with onset before age 10 years

Seven families with six different SPG3A mutations were identified among 106 with autosomal dominant hereditary spastic paraplegia (HSP). Two mutations were novel (T162P, C375R). SPG3A was twice as frequent as SPG4 in patients with onset before age 10 years (31.8%). Later onset was not observed. The phenotype was pure HSP, but disease duration was longer than in non-SPG3A/SPG4 patients, leading ultimately to greater handicap.     

Novel SPG6 mutation p.A100T in a Japanese family with autosomal dominant form of hereditary spastic paraplegia.

We describe a Japanese family in which inheritance of a novel mutation p.A100T in SPG6 resulted in an autosomal dominant form of hereditary spastic paraplegia (ADHSP). Clinical investigation showed a pure form of HSP. Our study demonstrates further allelic heterogeneity of SPG6.     

Investigation of mitochondrial function in hereditary spastic paraparesis

Following the association of hereditary spastic paraparesis (HSP) with mutation in the paraplegin gene (SPG7) and mitochondrial dysfunction, we wished to investigate whether mitochondrial dysfunction might be associated with other forms of HSP. Five cases of HSP caused by mutation in the spastin gene (SPG4) and nine cases with HSP with mutation in the spastin and paraplegin genes excluded (non-SPG4/SPG7), were investigated for mitochondrial dysfunction. Muscle tissue from the HSP groups and a control group was analysed histochemically and spectrophotometrically for mitochondrial dysfunction. A significant decrease in mitochondrial respiratory chain complexes I and IV was demonstrated in the non-SPG4/SPG7 group. No abnormality was detected in the SPG4 group. We therefore conclude that there is evidence for mitochondrial dysfunction in non-SPG4/SPG7 HSP. There is no evidence for mitochondrial dysfunction in the pathogenesis of spastin-related HSP.     

Clinical and genetic findings in a series of Italian children with pure hereditary spastic paraplegia

Background: Hereditary spastic paraplegias (HSP) are a group of neurodegenerative disorders characterized by progressive lower extremity spastic weakness. SPG7, SPG4 and SPG3A are some of the autosomal genes recently found as mutated in recessive or dominant forms of HSP in childhood. SPG31 is more often associated with a pure spastic paraplegia phenotype, but genotype–phenotype correlation is still unclear. The aims of the current study was: (i) to verify the mutational frequency of SPG4, SPG3A, SPG31 and SPG7 genes in our very‐well‐selected childhood sample, and (ii) to improve our knowledge about the clinical and electrophysiological HSP phenotypes and their possible correlation with a specific mutation. Methods: A sample of 14 Italian children affected by pure HSP (mean age at diagnosis 5.9 years) was extensively investigated with electrophysiological, neuroradiological and genetic tests. Results: Three SPG4 mutations were identified in three patients: two novel missense mutations, both sporadic, and one multiexonic deletion already reported. A novel large deletion in SPG31 gene involving exons 2–5 was also detected in one young patient. No mutations in the SPG7 and in the SPG3A genes were found. Conclusions: Our data confirm that HSP represent a heterogeneous group of genetic neurodegenerative disorders, also in sporadic or autosomal recessive early onset forms. Multiplex Ligation‐dependent Probe Amplification‐based mutation screening for SPG4 and SPG31 genes would be added to sequencing‐based screening of SPG4, SPG31 and SPG3A genes in the routine diagnosis of HSP children.     

Exome sequencing in a family with intellectual disability, early onset spasticity, and cerebellar atrophy detects a novel mutation in EXOSC3

Whole exome sequencing in two-generational kindred from Bangladesh with early onset spasticity, mild intellectual disability, distal amyotrophy, and cerebellar atrophy transmitted as an autosomal recessive trait identified the following two missense mutations in the EXOSC3 gene: a novel p.V80F mutation and a known p.D132A change previously associated with mild variants of pontocerebellar hypoplasia type 1. This study confirms the involvement of RNA processing proteins in disorders with motor neuron and cerebellar degeneration overlapping with spinocerebellar ataxia 36 and rare forms of hereditary spastic paraplegia with cerebellar features.