METHODS: We studied 5 affected individuals from 3 unrelated families manifesting global developmental delay, postnatal microcephaly, and hypotonia. We used exome sequencing and prioritized variants that were subsequently characterized using immunofluorescence, immunoblotting, pulldown assays, and RNA sequencing.
RESULTS: We identified biallelic variants in ZFTRAF1, encoding a protein of yet unknown function. Four affected individuals from 2 unrelated families segregated 2 homozygous frameshift variants in ZFTRAF1, whereas, in the third family, an intronic splice site variant was detected. We investigated ZFTRAF1 at the cellular level and signified it as a nucleocytoplasmic protein in different human cell lines. ZFTRAF1 was completely absent in the fibroblasts of 2 affected individuals. We also identified 110 interacting proteins enriched in mRNA processing and autophagy-related pathways. Based on profiling of autophagy markers, patient-derived fibroblasts show irregularities in the protein degradation process.
CONCLUSIONS: Thus, our findings suggest that biallelic variants of ZFTRAF1 cause a severe neurodevelopmental disorder.
方法:我们研究了来自三个不相关家庭的五个受影响的个体,这些个体表现出整体发育迟缓,产后小头畸形,和低张力。我们采用外显子组测序和优先变异,随后使用免疫荧光进行表征,免疫印迹,下拉分析,和RNA测序。
结果:我们在ZFTRAF1中鉴定了双等位基因变体,编码一种功能未知的蛋白质。来自两个无关家庭的四个受影响的个体在ZFTRAF1中隔离了两个纯合移码变体,而在第三个家庭,检测到内含子剪接位点变异。我们在细胞水平上研究了ZFTRAF1,并将其表示为不同人类细胞系中的核质蛋白。ZFTRAF1在两个受影响个体的成纤维细胞中完全不存在。我们还鉴定了110种富含mRNA加工和自噬相关途径的相互作用蛋白。基于自噬标志物的分析,患者来源的成纤维细胞在蛋白质降解过程中显示不规则。
结论:因此,我们的发现提示ZFTRAF1双等位基因变异体可导致严重的神经发育障碍.