Institute of Pediatric Research, Children's Hospital of Soochow University, Suzhou, Jiangsu Province, People's Republic of China.
Institute for Advanced Study and School of Physical Science and Technology, Soochow University, Suzhou, Jiangsu Province, People's Republic of China.
Pediatr Res. 2022 Feb;91(3):565-571. doi: 10.1038/s41390-021-01468-9. Epub 2021 Mar 31.
Lethal neonatal rigidity and multifocal seizure syndrome (RMFSL) is caused by variants in BRAT1 (BRCA1-associated protein required for ATM activation-1). However, the molecular mechanism of RMFSL is still unclear.
An RMFSL infant was recruited and the peripheral blood samples from his trio-family were collected. The genomic DNA was extracted, and then the whole-exome sequencing was performed. The expression of BRAT1 was analyzed by Western blotting. The subcellular localization of BRAT1 and MitoSOX (mitochondrial superoxide level) was investigated by confocal microscopy. The RNA samples were obtained from transfected cells, and then the RNA sequencing was performed.
In this study, a novel homozygous BRAT1 variant c.233G > C with amino acid change of R with P at residue 78 (R78P) was identified. This variant altered the peptide structure and subcellular localization, as well as the expression in vitro. However, R78P did not alter the ability of BRAT1 to downregulate MitoSOX in mitochondria. Meanwhile, R78P BRAT1 was positively correlated with temporal lobe epilepsy, autosomal recessive primary microcephaly, defective/absent horizontal voluntary eye movements, and neuron apoptotic process as indicated by gene set enrichment analysis (GSEA).
The BRAT1 variant spectrum has been expanded, which will be helpful for genetic counseling. We also explored the molecular mechanism altered by R78P, which will provide a better understanding of the pathogenesis of RMFSL.
The detailed course of an infant with lethal neonatal RMFSL was depicted. A novel disease-causing variant R78P in BRAT1 for lethal neonatal RMFSL was identified. R78P led to reduced BRAT1 expression and nuclear localization in vitro. R78P did not alter the ability of BRAT1 to downregulate MitoSOX in the mitochondria. The variant R78P in BRAT1 was positively correlated with temporal lobe epilepsy, autosomal recessive primary microcephaly, defective/absent horizontal voluntary eye movements, and neuron apoptotic process as indicated by GSEA.
致死性新生儿僵硬和多灶性癫痫综合征（RMFSL）是由 BRAT1（BRCA1 相关蛋白，ATM 激活所必需的-1）变异引起的。然而，RMFSL 的分子机制尚不清楚。
招募一名 RMFSL 婴儿，并采集其三代家族的外周血样。提取基因组 DNA，然后进行全外显子组测序。通过 Western blot 分析 BRAT1 的表达。通过共聚焦显微镜研究 BRAT1 和 MitoSOX（线粒体超氧化物水平）的亚细胞定位。从转染细胞中获得 RNA 样品，然后进行 RNA 测序。
本研究鉴定出一种新型纯合 BRAT1 变体 c.233G > C，导致第 78 位氨基酸残基 R 突变为 P（R78P）。该变体改变了肽结构和亚细胞定位，以及体外表达。然而，R78P 并未改变 BRAT1 下调线粒体中 MitoSOX 的能力。同时，基因集富集分析（GSEA）表明，R78P BRAT1 与颞叶癫痫、常染色体隐性原发性小头畸形、水平自主眼球运动缺失/缺陷以及神经元凋亡过程呈正相关。
BRAT1 变异谱得到扩展，这将有助于遗传咨询。我们还探索了 R78P 改变的分子机制，这将有助于更好地了解 RMFSL 的发病机制。
详细描述了一名患有致命性新生儿 RMFSL 婴儿的详细病程。鉴定出 BRAT1 中导致致命性新生儿 RMFSL 的新型致病变异 R78P。R78P 导致体外 BRAT1 表达和核定位减少。R78P 并未改变 BRAT1 下调线粒体中 MitoSOX 的能力。GSEA 表明，BRAT1 中的变体 R78P 与颞叶癫痫、常染色体隐性原发性小头畸形、水平自主眼球运动缺失/缺陷以及神经元凋亡过程呈正相关。
