Identification of New Human Imprinted Genes: A Novel Approach

“印记”基因对正常的人类生长发育至关重要。几乎我们所有的基因都是成对出现的，每对基因的一个拷贝遗传自母亲（母系），另一个拷贝遗传自父亲（父系）。对于我们绝大多数的基因对来说，从父母双方遗传来的拷贝是平等表达的。然而，印迹基因以亲本起源特异性的方式表达。也就是说，基因是从母系或父系拷贝中转录（读取）的，而不是同时从母系或父系拷贝中转录（读取），这些基因的表达在特定组织中可能不同。这种特殊类型的转录实现的机制被称为表观遗传。表观遗传标记，如DNA甲基化，通过使基因无法进入细胞内的转录机制，从本质上使基因沉默。印迹基因通常在一对亲本基因上有相反的表观遗传标记，一个甲基化（沉默），另一个未甲基化（转录）。这被称为差异DNA甲基化。

"Imprinted" genes are critical for normal human growth and development. Almost all of our genes occur in pairs, with one copy of each gene pair inherited from our mother (maternal) and the other from our father (paternal). For the vast majority of our gene pairs, the copy inherited from each parent is expressed equally. However, imprinted genes are expressed in a parent of origin-specific manner. That is, the genes are transcribed (read) from either the maternal or paternal copy, not both, and the expression of these genes may differ in specific tissues. The mechanism by which this special type of transcription is achieved is termed epigenetic. Epigenetic marks, such as DNA methylation, essentially silence the gene by making it inaccessible to the transcription machinery in the cell. Imprinted genes typically have opposite epigenetic marks on the two parental genes in the pair, one methylated (silenced) and the other not methylated (transcribed). This is called differential DNA methylation.