Molecular assay for an intronic variant in NUP93 that causes steroid resistant nephrotic syndrome
Molecular assay for an intronic variant in NUP93 that causes steroid resistant nephrotic syndrome
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DOI：
10.1038/s10038-019-0606-4
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发表时间：
2019-07-01
影响因子：
3.5
通讯作者：
Iijima, Kazumoto
中科院分区：
文献类型：
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作者：
Rossanti, Rini;Shono, Akemi;Iijima, Kazumoto
分子遗传学的进展显示，大约30%的类固醇耐药肾病综合征（SRNS）病例是由单基因突变引起的。超过50个基因负责SRNS。一个这样的基因是核孔蛋白，93-KD（NUP 93）。到目前为止，很少有研究报道NUP 93在SRNS中的突变。在这里，我们描述了一个NUP 93双等位基因突变的9岁男孩与局灶节段性肾小球硬化症（FSGS）。值得注意的是，一个突变包括一个内含子变体;我们进行了体内和体外分析，以表征这种变体。我们在NUP 93中发现了两个杂合突变：内含子19中的c.2137- 18 G>A和外显子8中的一个新的无义突变c.727A>T（p.Lys243*）。我们进行了RNA测序和体外剪接试验，通过使用minigene构建，结合蛋白质表达分析，以确定内含子变异的致病性。RNA测序和体外剪接分析均显示内含子变体的外显子20跳跃。在蛋白质表达分析中，观察到内含子变体的异常亚细胞定位，在细胞质中具有小的点状囊泡。综上所述，我们得出结论，c.2137- 18 G>A与异常剪接引起的致病性有关。NUP 93变异非常罕见;然而，我们已经证明，即使是NUP 93中的内含子变异也会导致SRNS。这项研究提供了一个基本的方法来验证内含子变异，以及关于罕见基因变异引起的SRNS的临床谱的新见解。
Advances in molecular genetics have revealed that approximately 30% of cases with steroid-resistant nephrotic syndrome (SRNS) are caused by single-gene mutations. More than 50 genes are responsible for SRNS. One such gene is the nucleoporin, 93-KD (NUP93). Thus far, few studies have reported mutations of NUP93 in SRNS. Here, we describe an NUP93 biallelic mutation in a 9-year-old boy with focal segmental glomerular sclerosis (FSGS). Notably, one mutation comprised an intronic variant; we conducted in vivo and in vitro analysis to characterize this variant. We found two heterozygous mutations in NUP93: c.2137-18G>A in intron 19 and a novel nonsense mutation c.727A>T (p.Lys243*) in exon 8. We conducted RNA sequencing and in vitro splicing assays by using minigene construction, combined with protein expression analysis to determine the pathogenicity of the intronic variant. Both RNA sequencing and in vitro splicing assay showed exon 20-skipping by the intronic variant. In protein expression analysis, aberrant subcellular localization with small punctate vesicles in the cytoplasm was observed for the intronic variant. Taken together, we concluded that c.2137-18G>A was linked to pathogenicity due to aberrant splicing. NUP93 variants are quite rare; however, we have shown that even intronic variants in NUP93 can cause SRNS. This study provides a fundamental approach to validate the intronic variant, as well as new insights regarding the clinical spectrum of SRNS caused by rare gene variants.