5-hydroxymethylcytosine (5hmC) is a naturally existing component in mammalian genomic DNA and is regarded as the sixth DNA base. Accumulating studies have revealed the essential role of 5hmC in embryonic devel-opment, brain function and cancer research. Compared to another well-known cytosine methylation derivate, 5-methyl-cytosine (5mC), the detection of 5hmC is difficult for its lower lever existing in most tissues. To distinguish 5hmC from other cytosine derivates, the methods using chemical or enzymatic DNA treatment, have been applied in target-ed 5hmC detection or non-targeted 5hmC enrichment. Therefore, profiling DNA hydroxymethylcytosine by sensitive, accurate and reliable method is crucial for epigenetic study. This review discusses the principles behind recently de-veloped techniques for 5hmC quantification and mapping. By comparing the advantages and shortcomings of these methods, the general guidelines were provided on how to select appropriate methods for specific experimental contexts.%被称为"第六种碱基"的5-羟甲基胞嘧啶(5-hydroxymethylcytosine,5hmC),广泛分布于多种哺乳动物的组织和细胞中,与胚胎发育、神经系统功能以及肿瘤研究高度相关.与5-甲基胞嘧啶(5-methylcytosine,5mC)相比,5hmC在组织中含量更低,难以精确的检测.随着研究的深入,5hmC参与的重要生物学作用逐渐被人们发现,同时也促使着5hmC的检测和定量方法不断发展.为了区分5hmC与其他胞嘧啶衍生物,很多利用化学或者酶学修饰实现靶向检测或非靶向富集5hmC的方法应运而生.因此,选择并发展灵敏、准确、可靠的5hmC检测技术对于表观遗传研究至关重要.本文重点综述了近年来发展起来的5hmC检测和测序技术,通过比较分析各种方法的优缺点,为研究人员选择特定合适的方法开展相关研究提供重要的参考.
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