Supplementary Material for: Severe Progressive Autism Associated with Two de novo Changes: A 2.6-Mb 2q31.1 Deletion and a Balanced t(14;21)(q21.1;p11.2) Translocation with Long-Range Epigenetic Silencing of <i>LRFN5</i> Expression

In a 19-year-old severely autistic and mentally retarded girl, a balanced de novo t(14;21)(q21.1;p11.2) translocation was found in addition to a de novo 2.6-Mb 2q31.1 deletion containing 15 protein-encoding genes. To investigate if the translocation might contribute to developmental stagnation at the age of 2 years with later regression of skills, i.e. a more severe phenotype than expected from the 2q31.1 deletion, the epigenetic status and expression of genes proximal and distal to the 14q21.1 breakpoint were investigated in Ebstein Barr Virus-transformed lymphoblast and primary skin fibroblast cells. The 14q21.1 breakpoint was found to be located between a cluster of 7 genes 0.1 Mb upstream, starting with <i>FBXO33</i>, and the single and isolated <i>LRFN5</i> gene 2.1 Mb downstream. Only expression of <i>LRFN5</i> appeared to be affected by its novel genomic context. In patient fibroblasts, <i>LRFN5</i> expression was 10-fold reduced compared to <i>LRFN5</i> expressed in control fibroblasts. In addition, a relative increase in trimethylated histone H3 lysine 9 (H3K9M3)-associated DNA starting exactly at the translocation breakpoint and going 2.5 Mb beyond the <i>LRFN5</i> gene was found. At the <i>LRFN5</i> promoter, there was a distinct peak of trimethylated histone H3 lysine 27 (H3K27M3)-associated DNA in addition to a diminished trimethylated histone H3 lysine 4 (H3K4M3) level. We speculate that dysregulation of <i>LRFN5</i>, a postsynaptic density-associated gene, may contribute to the patient’s autism, even though 2 other patients with 14q13.2q21.3 deletions that included <i>LRFN5</i> were not autistic. More significantly, we have shown that translocations may influence gene expression more than 2 Mb away from the translocation breakpoint.

本研究针对一名19岁重度自闭症伴智力障碍女性患者，检出其同时携带新发平衡型t(14;21)(q21.1;p11.2)染色体易位，以及一段包含15个蛋白编码基因的2.6 Mb 2q31.1区域新发缺失。为探究该易位是否参与了患者2岁时出现的发育停滞及后续技能倒退表型——该表型较单纯2q31.1缺失预期的表型更为严重——我们在EB病毒（Epstein-Barr Virus，EBV）转化的淋巴母细胞与原代皮肤成纤维细胞中，对14q21.1断裂点（breakpoint）上下游区域的基因表观遗传状态（epigenetic status）与表达水平进行了检测。研究发现，14q21.1断裂点位于以<i>FBXO33</i>为起始的上游0.1 Mb处的7个基因簇，与下游2.1 Mb处的孤立基因<i>LRFN5</i>之间。仅<i>LRFN5</i>的表达似乎受到其所处全新基因组环境的影响：患者成纤维细胞中<i>LRFN5</i>的表达量较对照成纤维细胞降低了10倍。此外，我们在易位断裂点起始、延伸至<i>LRFN5</i>基因下游2.5 Mb的区域内，检测到了与组蛋白H3赖氨酸9三甲基化相关的DNA区域相对富集。在<i>LRFN5</i>的启动子（promoter）区域，除了组蛋白H3赖氨酸4三甲基化水平降低外，还出现了显著的组蛋白H3赖氨酸27三甲基化富集峰。我们推测，作为突触后致密物相关基因（postsynaptic density-associated gene）的<i>LRFN5</i>表达失调，可能参与了患者的自闭症表型发生——尽管此前另有2例携带包含<i>LRFN5</i>的14q13.2q21.3区域缺失的患者并未表现出自闭症症状。更为重要的是，本研究证实染色体易位可对易位断裂点2 Mb以外的基因表达产生影响。

搜集汇总

背景与挑战

背景概述

该数据集是自闭症研究的补充材料，包含图表文件，发布于2010年。研究针对一名严重自闭症女性，发现两个de novo遗传变化（2q31.1缺失和t(14;21)易位），并揭示了易位通过长距离表观遗传沉默导致LRFN5基因表达显著降低，这可能与自闭症表型相关，强调了易位对远端基因表达的影响。