Regions of genomic DNA can become single-stranded in the course of normal replication and transcription as well as during DNA repair. Abnormal repair and replication intermediates can contain large stretches of persistent single-stranded DNA, which is extremely vulnerable to DNA damaging agents and hypermutation. Since such single-stranded DNA spans only a fraction of the genome at a given instance, hypermutation in these regions leads to tightly-spaced mutation clusters. This phenomenon of hypermutation in single-stranded DNA has been documented in several experimental models as well as in cancer genomes. Recently, hypermutated single-stranded RNA viral genomes also have been documented. Moreover, indications of hypermutation in single-stranded DNA may also be found in the human germline. This review will summarize key current knowledge and the recent developments in understanding the diverse mechanisms and sources of ssDNA hypermutation.

中文翻译：

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单链DNA的超突变。

基因组DNA区域可以在正常复制和转录过程以及DNA修复过程中变成单链。异常的修复和复制中间体可能含有大量的持久单链DNA，这极易受到DNA破坏剂和超突变的影响。由于这种单链DNA在给定的情况下仅跨越基因组的一小部分，因此这些区域的超突变会导致紧密排列的突变簇。单链DNA中的这种高突变现象已经在一些实验模型以及癌症基因组中得到了证明。最近，也已经记录了超突变的单链RNA病毒基因组。此外，在人种系中也可能发现单链DNA超突变的迹象。