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Objective To analyze the clinical manifestations and genetic mutations in 3 pedigrees with hereditary spastic paraplegia (HSP).Methods Three pedigrees diagnosed as having HSP in our hospital from January 2014 to November 2015,were chosen;the clinical manifestations,electrophysiology and imaging features of the patients in these three families were analyzed.Genomic DNA was extracted from peripheral venous blood,and the targeted gene capturing was employed to identify the disease-causing genes of these patients.Results The patients from the first family was familiar HSP,and the main clinical features were progressive lower limbs weakness and abnormal gait without cognitive impairment;the patients from the second family were familiar HSP and those from the third family were HSP without family history,and the main clinical features of the two pedigrees were slowly progressive spastic paraplegia and cognitive impairment.In addition,thin corpus callosum was visible in MR imaging of family three.Genetic testing showed the first family presented with a known mutation c.715C＞T ofA TL1 exon 7 and the loci co-segregated in the family.The second family presented with novel compound heterozygous mutations in the SPG11 gene:c.3099_3103delGTTTG mutation of exon 17and c3817 3818insTGA mutation of exon 22;novel compound heterozygous mutations in the SPG11 gene in the third family were detected as follows:c.6194C ＞G mutation of exon 32 and c.5121+1C＞T splicing mutation ofintro 29.Conclusions Four novel mutations in SPG11 gene and one known mutation in A TL1 gene are found,which enriches the known HSP mutation types.Targeted gene capture is an efficient and rapid tool for identifying the causation of some complex and genetically heterogeneous neurodegenerative diseases.
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BACKGROUND AND PURPOSE: Hereditary spastic paraplegia (HSP) is a genetically heterogeneous group of neurodegenerative disorders that are characterized by progressive spasticity and weakness of the lower limbs. Mutations in the spastin gene (SPAST) are the most common causes of HSP, accounting for 40-67% of autosomal dominant HSP (AD-HSP) and 12-18% of sporadic cases. Mutations in the atlastin-1 gene (ATL1) and receptor expression-enhancing protein 1 gene (REEP1) are the second and third most common causes of AD-HSP, respectively. METHODS: Direct sequence analysis was used to screen mutations in SPAST, ATL1, and REEP1 in 27 unrelated Korean patients with pure and complicated HSP. Multiplex ligation-dependent probe amplification was also performed to detect copy-number variations of the three genes. RESULTS: Ten different SPAST mutations were identified in 11 probands, of which the following 6 were novel: c.760A>T, c.131C>A, c.1351_1353delAGA, c.376_377dupTA, c.1114A>G, and c.1372A>C. Most patients with SPAST mutations had AD-HSP (10/11, 91%), and the frequency of SPAST mutations accounted for 66.7% (10/15) of the AD-HSP patients. No significant correlation was found between the presence of the SPAST mutation and any of the various clinical parameters of pure HSP. No ATL1 and REEP1 mutations were detected. CONCLUSIONS: We conclude that SPAST mutations are responsible for most Korean cases of genetically confirmed AD-HSP. Our observation of the absence of ATL1 and REEP1 mutations needs to be confirmed in larger series.