Advance of research on Hereditary spastic paraplegia type 4 / 中华医学遗传学杂志

Spastic paraplegia type 4 (SPG4) is the most common type of autosomally inherited spastic paraplegia. Its main clinical features include typical simple hereditary spastic paraplegia, with neurological impairments limited to lower limb spasticity, hypertonic bladder dysfunction, and mild weakening of lower limb vibration sensation, without accompanying features such as nerve atrophy, ataxia, cognitive impairment, seizures, and muscle tone disorders. SPAST is the main pathogenic gene underlying SPG4, and various pathogenic SPAST variants have been discovered. This disease has featured a high degree of clinical heterogeneity, and the same pathogenic variant can have different age of onset and severity among different patients and even within the same family. There is a lack of systematic research on the correlation between the genotype and phenotype of SPG4, and the pathogenic mechanism has remained controversial. This article has provided a review for the clinical characteristics, pathogenic gene characteristics, correlation between the genotype and phenotype, and pathogenic mechanism of this disease, with an aim to provide reference for its clinical diagnosis and treatment.

Identification of SPAST gene variant in a pedigree affected with hereditary spastic paraplegia type 4 / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a pedigree affected with hereditary spastic paraplegia type 4 (HSP4).@*METHODS@#Peripheral venous blood samples were taken from members of the four-generation pedigree and 50 healthy controls for the extraction of genomic DNA. Genes associated with peripheral neuropathy and hereditary spastic paraplegia were captured and subjected to targeted capture and next-generation sequencing. The results were confirmed by Sanger sequencing.@*RESULTS@#DNA sequencing suggested that the proband has carried a heterozygous c.1196C>G variant in exon 9 of the SPAST gene, which can cause substitution of serine by threonine at position 399 (p.Ser399Trp) and lead to change in the protein function. The same variant was also detected in other patients from the pedigree but not among unaffected individuals or the 50 healthy controls. Based on the ACMG 2015 guidelines, the variant was predicted to be possibly pathogenic.@*CONCLUSION@#The c.1196C>G variant of the SPAST gene probably underlay the HSP4 in this pedigree.

Novel deletion of SPAST in a Chinese family with hereditary spastic paraplegia

<p><b>INTRODUCTION</b>Hereditary spastic paraplegia (HSP) belongs to a large, heterogeneous group of progressive neurodegenerative diseases characterised by progressive lower extremity weakness and spasticity, which is caused by developmental failure or degeneration of motor axons in the corticospinal tract. Classical genetic studies have identified at least 46 genetic loci responsible for HSP.</p><p><b>METHODS</b>A genetic study was conducted on a four-generation Chinese family with autosomal dominant HSP. The SPAST gene was investigated using linkage analysis and direct sequencing. Findings were compared with unaffected family members and 50 normal, unaffected individuals who were matched for geographical ancestry.</p><p><b>RESULTS</b>We identified a novel 14-bp heterozygous deletion that induced a frameshift mutation in exon 15 of SPAST (SPG4). This mutation is predicted to have functional impact and found to cosegregate with the disease phenotype.</p><p><b>CONCLUSION</b>Our results have expanded the mutation spectrum of the SPAST gene. These findings could help clinicians provide prenatal diagnosis of affected foetuses in families with a known history of such neurodegenerative diseases.</p>

Construction of wild-type and mutant SPAST vectors for the study of molecular mechanism of hereditary spastic paraplegia / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To construct wild-type and mutant pEGFP SPAST vectors and to explore the molecular mechanism of hereditary spastic paraplegia.</p><p><b>METHODS</b>Mutant SPAST vector was constructed using overlap PCR method following construction of wild-type SPAST vector. Wild-type and mutant constructs were transfected to COS7 cells and subcellular localization of spastin was observed. Co-localizations of spastin and microtubule, spastin and mitochondria were viewed by immunofluorescence staining.</p><p><b>RESULTS</b>Wild-type spastin is localized in plasma, and mutant spastin did not change its cellular localization. Wild-type and mutant spastins did not co-localize with microtubules and mitochondria by immunofluorescence analysis.</p><p><b>CONCLUSION</b>Wild-type and mutant SPAST constructs were successfully generated. Mutant spastin did not change its localization in cells. Spastin does not co-localize with microtubules and mitochondria. This study may facilitate further studies on molecular mechanism of hereditary spastic paraplegia.</p>

Advances of genetic research on the SPG4 gene / 中华医学遗传学杂志

The hereditary spastic paraplegia (HSP), also known as Strumpell-Lorrain familial spasmodic paraplegia, is a highlighted clinical and genetic heterogeneity disorder with the prevalence of (2-9.6)/100,000. This disorder is characterized by progressive, usually severe spasticity and pyramidal weakness, predominantly in the lower limbs. Inheritance of this disease has been reported to be autosomal dominant (AD), autosomal recessive (AR), or X-linked recessive (XR), with the AD forms of HSP (ADHSP) being the most common type. At least 40 HSP gene loci have been localized and 19 genes have been identified. Forty percent of HSP cases are caused by mutations in the spastin (spastic paraplegia-4, SPG4) gene. Genetic diagnosis, the gold standard for diagnosis of the disease, may contribute to early diagnosis, presymptomatic diagnosis and prenatal diagnosis. The study of animal models plays an important role in revealing the molecular pathological mechanism of HSP. The known genetic research advances of the SPG4 gene are reviewed in this article.

Clinical characteristics and spastin gene mutation analysis on an autosomal dominant kindred with hereditary spastic paraplegia / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the clinical characteristics and analyze spastin gene mutation on a kindred with hereditary spastic paraplegia (HSP).</p><p><b>METHODS</b>All family members were studied through clinical examinations. The proband and another two patients in this kindred were subjected to electromyography (EMG) examinations. The proband was subjected to thoracic MRI examination too. Mutation analysis of spastin gene was screened by polymerase chain reaction combined with DNA sequencing in the proband and his father.</p><p><b>RESULTS</b>All patients in the kindred manifested as classical HSP. Thoracic MRI revealed atrophies of the spinal cord in the proband. No abnormal spastin gene mutation was detected in these two patients.</p><p><b>CONCLUSION</b>This kindred has typical clinical manifestations of HSP. The pathogenesis has no association with mutation of the exons of spastin gene.</p>

Spastin gene mutation in Chinese patients with hereditary spastic paraplegia / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the mutation characteristics of spastin gene in Chinese patients with hereditary spastic paraplegia (HSP) and thus provide a basis for the gene diagnosis of HSP.</p><p><b>METHODS</b>Mutation of spastin gene was screened by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) combined with DNA direct sequencing in 31 unrelated affected HSP individuals in China, of whom 22 were from autosomal dominant families and 9 were sporadic HSP patients. Co-segregation analysis was carried out after the finding of abnormal SSCP bands.</p><p><b>RESULTS</b>Six cases were found to have abnormal SCP bands, and among them, two missense mutations (T1258A, A1293G in exon 8) and one deletion mutation (1667delACT or 1668delCTA or 1669delTAC in exon 14) were found and all of them were not reported previously. They were all co-segregated with the disease and were localized within the functional domain of spastin gene. Besides, T1258A was seen in two unrelated families.</p><p><b>CONCLUSION</b>The mutation rate (18.2%) in autosomal dominant HSP in Chinese patients is comparatively low. Point mutation is the major mutation type and exon 8 may be the mutation hot spot.</p>