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Abstract：
The most common form of hereditary spastic paraplegia (HSP), SPG4 is caused by single nucleotide variants and microrearrangements in the SPAST gene. The high percentage of multi-exonic deletions or duplications observed in SPG4 patients is predisposed by the presence of a high frequency of Alu sequences in the gene sequence. In the present study, we analyzed DNA and RNA samples collected from patients with different microrearrangements in SPAST to map gene breakpoints and evaluate the mutation mechanism. The study group consisted of 69 individuals, including 50 SPG4 patients and 19 healthy relatives from 18 families. Affected family members from 17 families carried varying ranges of microrearrangements in the SPAST gene, while one individual had a single nucleotide variant in the 5\'UTR of SPAST. To detect the breakpoints of the SPAST gene, long-range PCR followed by sequencing was performed. The breakpoint sequence was detected for five different intragenic SPAST deletions and one duplication, revealing Alu-mediated microhomology at breakpoint junctions resulting from non-allelic homologous recombination in these patients. Furthermore, SPAST gene expression analysis was performed using patient RNA samples extracted from whole blood. Quantitative real-time PCR tests performed in 14 patients suggest no expression of transcripts with microrearrangements in 5 of them. The obtained data indicate that nonsense-mediated decay degradation is not the only mechanism of hereditary spastic paraplegia in patients with SPAST microrearrangements.
摘要：
遗传性痉挛性截瘫（HSP）的最常见形式，SPG4是由SPAST基因中的单核苷酸变体和微重排引起的。在SPG4患者中观察到的高百分比的多外显子缺失或重复是由于在基因序列中存在高频率的Alu序列而易感的。在本研究中,我们分析了SPAST中不同微重排患者的DNA和RNA样本,以定位基因断点并评估突变机制.研究组由69人组成，包括50名SPG4患者和来自18个家庭的19名健康亲属。来自17个家庭的受影响的家庭成员在SPAST基因中携带不同范围的微重排，而一个个体在SPAST的5'UTR中具有单核苷酸变异。为了检测SPAST基因的断点，进行长范围PCR,然后进行测序.检测到断点序列有五个不同的基因内SPAST缺失和一个重复，揭示了这些患者中非等位基因同源重组导致的断点连接处的Alu介导的微同源性。此外，使用从全血提取的患者RNA样品进行SPAST基因表达分析。在14例患者中进行的定量实时PCR测试表明，其中5例未表达具有微重排的转录本。获得的数据表明，无义介导的衰变降解并不是SPAST微重排患者遗传性痉挛性截瘫的唯一机制。
