背景:马凡氏综合征(MFS)是一种复杂的遗传性系统性结缔组织疾病。众所周知,遗传因素在MFS的进展中起着关键作用,几乎所有病例都归因于FBN1基因的变异。
方法:我们调查了一个跨越两代的MFS的中国家庭。全外显子组测序,在硅分析中,小基因构建体,转染,RT-PCR,和蛋白质二级结构分析用于分析先证者及其父亲的基因型。
结果:先证者及其父亲的主要临床表现为左侧晶状体半脱位和高度近视伴胸肌畸形。全外显子组测序在FBN1基因的一个非经典剪接位点发现了一个新的单核苷酸变异体(SNV),c.443-3C>G.这种变异导致两种异常的mRNA转录物,导致移码和帧内插入。进一步的体外实验表明,FBN1中的c.443-3C>G变体是致病性的,并且在功能上是有害的。
结论:这项研究发现了一种新的内含子致病性FBN1:c.443-3C>G基因变体,这导致了两种不同的异常剪接效应。进一步的功能分析扩展了变异谱,并为单基因疾病(PGT-M)的植入前遗传测试提供了强有力的指示和充分的基础。
BACKGROUND: Marfan syndrome (MFS) is a complex genetic systemic connective tissue disorder. It is well known that genetic factors play a critical role in the progression of MFS, with nearly all cases attributed to variants in the FBN1 gene.
METHODS: We investigated a Chinese family with MFS spanning two generations. Whole exome sequencing, in silico analysis, minigene constructs, transfection, RT-PCR, and protein secondary structure analysis were used to analyze the genotype of the proband and his father.
RESULTS: The main clinical manifestations of the proband and his father were subluxation of the left lens and high myopia with pectus deformity. Whole exome sequencing identified a novel single nucleotide variant (SNV) in the FBN1 gene at a non-canonical splice site, c.443-3C>G. This variant resulted in two abnormal mRNA transcripts, leading to a frameshift and an in-frame insertion. Further in vitro experiments indicated that the c.443-3C>G variant in FBN1 was pathogenic and functionally harmful.
CONCLUSIONS: This research identified a novel intronic pathogenic FBN1: c.443-3C>G gene variant, which led to two different aberrant splicing effects. Further functional analysis expands the variant spectrum and provides a strong indication and sufficient basis for preimplantation genetic testing for monogenic disease (PGT-M).