Fancello Tatiana, Dardis Andrea, Rosano Camillo, Tarugi Patrizia, Tappino Barbara, Zampieri Stefania, Pinotti Elisa, Corsolini Fabio, Fecarotta Simona, D'Amico Adele, Di Rocco Maja, Uziel Graziella, Calandra Sebastiano, Bembi Bruno, Filocamo Mirella
Dipartimento di Scienze Biomediche, Università di Modena e Reggio Emilia, Modena, Italy.
Neurogenetics. 2009 Jul;10(3):229-39. doi: 10.1007/s10048-009-0175-3. Epub 2009 Feb 28.
Niemann-Pick C, the autosomal recessive neuro-visceral disease resulting from a failure of cholesterol trafficking within the endosomal-lysosomal pathway, is due to mutations in NPC1 or NPC2 genes. We characterized 34 unrelated patients including 32 patients with mutations in NPC1 gene and two patients in NPC2 gene. Overall, 33 distinct genotypes were encountered. Among the 21 unpublished NPC1 alleles, 15 were due to point mutations resulting in 13 codon replacements (p.C100S, p.P237L, p.R389L, p.L472H, p.Y634C, p.S636F, p.V780G, p.Q921P, p.Y1019C, p.R1077Q, p.L1102F, p.A1187V, and p.L1191F) and in two premature stop codons (p.R934X and p.Q447X); a new mutant carried two in cis mutations, p.[L648H;M1142T] and four other NPC1 alleles were small deletions/insertions leading both to frame shifts and premature protein truncations (p.C31WfsX26, p.F284LfsX26, p.E1188fsX54, and p.T1205NfsX53). Finally, the new intronic c.464-2A>C change at the 3' acceptor splice site of intron 4 affected NPC1 messenger RNA processing. We also found a new NPC2 mutant caused by a change of the first codon (p.M1L). The novel missense mutations were further investigated by two bioinformatics approaches. Panther proein classification system computationally predicted the detrimental effect of all new missense mutations occurring at evolutionary conserved positions. The other bioinformatics approach was based on prediction of structural alterations induced by missense mutations on the NPC1 atomic models. The in silico analysis predicted protein malfunctioning and/or local folding alteration for most missense mutations. Moreover, the effects of the missense mutations (p.Y634C, p.S636F, p.L648H, and p.V780G) affecting the sterol-sensing domain (SSD) were evaluated by docking simulation between the atomic coordinates of SSD model and cholesterol.
尼曼-皮克病C型是一种常染色体隐性神经内脏疾病，由内体-溶酶体途径中胆固醇转运功能障碍引起，是由NPC1或NPC2基因突变所致。我们对34例无亲缘关系的患者进行了特征分析，其中包括32例NPC1基因突变患者和2例NPC2基因突变患者。总体而言，共发现33种不同的基因型。在21个未发表的NPC1等位基因中，15个是点突变，导致13个密码子替换（p.C100S、p.P237L、p.R389L、p.L472H、p.Y634C、p.S636F、p.V780G、p.Q921P、p.Y1019C、p.R1077Q、p.L1102F、p.A1187V和p.L1191F）以及两个提前终止密码子（p.R934X和p.Q447X）；一个新的突变体携带两个顺式突变，p.[L648H;M1142T]，另外四个NPC1等位基因是小的缺失/插入，均导致移码和蛋白质提前截短（p.C31WfsX26、p.F284LfsX26、p.E1188fsX54和p.T1205NfsX53）。最后，内含子4的3'剪接受体位点处新的内含子c.464-2A>C变化影响了NPC1信使核糖核酸的加工过程。我们还发现了一个由第一个密码子改变（p.M1L）引起的新的NPC2突变体。通过两种生物信息学方法对这些新的错义突变进行了进一步研究。Panther蛋白质分类系统通过计算预测了所有发生在进化保守位置的新错义突变的有害影响。另一种生物信息学方法是基于预测错义突变对NPC1原子模型诱导的结构改变。计算机模拟分析预测大多数错义突变会导致蛋白质功能异常和/或局部折叠改变。此外，通过固醇感应结构域（SSD）模型的原子坐标与胆固醇之间的对接模拟，评估了影响SSD的错义突变（p.Y634C、p.S636F、p.L648H和p.V780G）的作用。
