Munshi Anjana, Duvvuri Shanti
Department of Genetics, Shadan PG Centre for Biosciences, Khairtabad Hyderabad 500016, India.
J Genet Genomics. 2007 Feb;34(2):93-103. doi: 10.1016/S1673-8527(07)60010-1.
Genomic imprinting is an epigenetic mechanism that produces functional differences between the paternal and maternal genomes and plays an essential role in mammalian development and growth. There are a number of genes in our genomes that are subject to genomic imprinting where one parent's copy of the gene is expressed while the other is silent. Silencing of one allele predetermines that any function ascribed to that gene are now dependant on the single active copy. Possession of only a single active allele can lead to deleterious health consequences in humans. If imprinted genes are crucial in mammalian development, one would also expect mutations in these genes to cause diseases. Since imprinting is an epigenetic mechanism, mistakes in maintaining epigenetic mark also cause imprinting disorders. Here we in this review focus on the current understanding of this unique genetic mechanism more than two decades after the first description of the imprinting phenomenon was given by McGrath and Solter. Although the possible molecular mechanisms by which imprinting is imposed and maintained are being identified, we have a long way to go in understanding the molecular mechanisms that regulate the expression of these oddly behaving genes, the function of imprinting and the evolution. Post genomic technologies might ultimately lead to a better understanding of the 'imprinting effects'.
基因组印记是一种表观遗传机制，它在父本和母本基因组之间产生功能差异，并在哺乳动物的发育和生长中发挥重要作用。我们的基因组中有许多基因受到基因组印记的影响，其中一个亲本的基因拷贝表达，而另一个则沉默。一个等位基因的沉默决定了该基因的任何功能现在都依赖于单一的活性拷贝。仅拥有一个活性等位基因会给人类带来有害的健康后果。如果印记基因在哺乳动物发育中至关重要，人们也会预期这些基因的突变会导致疾病。由于印记是一种表观遗传机制，维持表观遗传标记时的错误也会导致印记障碍。在McGrath和Solter首次描述印记现象二十多年后，我们在这篇综述中重点关注对这种独特遗传机制的当前理解。尽管正在确定施加和维持印记的可能分子机制，但在理解调节这些行为异常基因表达的分子机制、印记的功能和进化方面，我们还有很长的路要走。后基因组技术最终可能会让我们更好地理解“印记效应”。
