Identification and expression analysis of spastin gene mutations in hereditary spastic paraplegia
Identification and expression analysis of spastin gene mutations in hereditary spastic paraplegia
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DOI：
10.1086/320111
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发表时间：
2001-05-01
影响因子：
9.8
通讯作者：
Marchuk, DA
中科院分区：
文献类型：
--
作者：
Svenson, IK;Ashley-Koch, AE;Marchuk, DA
纯遗传性痉挛性截瘫（SPG）4型是常染色体显性遗传性SPG的最常见形式，SPG是一种主要以下肢反射亢进和进行性痉挛为特征的神经退行性疾病。它是由编码痉挛蛋白（ATP酶AAA家族的成员）的基因突变引起的。我们已经筛选了15个家庭的痉挛基因突变与连锁的痉挛基因位点，SPG 4一致，并已确定11个突变，其中10个是新的。五个突变的确定是在非不变的剪接序列。来自患者的mRNA的逆转录PCR分析显示，这五种突变中的每一种都导致异常剪接。一个突变被发现是“渗漏”或部分渗透;也就是说，突变等位基因产生突变（跳过外显子）和野生型（全长）转录本。这种现象在体外剪接实验中再现，其中小基因剪接载体构建体仅在内源性剪接点侧接跳过的外显子的剪接点的背景下。在不存在内源性剪接点的情况下，仅检测到突变体转录物。至少一个泄漏突变的存在表明，野生型痉挛蛋白表达水平的相对较小的差异可以有显着的功能后果。这可能至少部分地解释了与SPG 4相关的SPG家族中和家族内发生的发病年龄、症状严重程度和症状进展率的广泛范围。此外，这些结果表明，谨慎的解释数据单独获得的小基因构建体，以研究序列变异对剪接的影响。在这些构建体中缺乏完整的基因组序列背景可以掩盖突变的重要功能后果。
Pure hereditary spastic paraplegia (SPG) type 4 is the most common form of autosomal dominant hereditary SPG, a neurodegenerative disease characterized primarily by hyperreflexia and progressive spasticity of the lower limbs. It is caused by mutations in the gene encoding spastin, a member of the AAA family of ATPases. We have screened the spastin gene for mutations in 15 families consistent with linkage to the spastin gene locus, SPG4, and have identified 11 mutations, 10 of which are novel. Five of the mutations identified are in noninvariant splice-junction sequences. Reverse transcription-PCR analysis of mRNA from patients shows that each of these five mutations results in aberrant splicing. One mutation was found to be "leaky," or partially penetrant; that is, the mutant allele produced both mutant (skipped exon) and wild-type (full-length) transcripts. This phenomenon was reproduced in in vitro splicing experiments, with a minigene splicing-vector construct only in the context of the endogenous splice junctions flanking the splice junctions of the skipped exon. In the absence of endogenous splice junctions, only mutant transcript was detected. The existence of at least one leaky mutation suggests that relatively small differences in the level of wild-type spastin expression can have significant functional consequences. This may account, at least in part, for the wide ranges in age at onset, symptom severity, and rate of symptom progression that have been reported to occur both among and within families with SPG linked to SPG4. In addition, these results suggest caution in the interpretation of data solely obtained with minigene constructs to study the effects of sequence variation on splicing. The lack of full genomic sequence context in these constructs can mask important functional consequences of the mutation.