Duplications of large genomic segments provide genetic diversity in genome evolution. Despite their importance, how these duplications are generated remains uncertain, particularly for distant duplicated genomic segments. Here we provide evidence of the participation of circular DNA intermediates in the single generation of some large human segmental duplications. A specific reversion of sequence order from A-B/C-D to B-A/D-C between duplicated segments and the presence of only microhomologies and short indels at the evolutionary breakpoints suggest a circularization of the donor ancestral locus and an accidental replicative interaction with the acceptor locus. This novel mechanism of random genomic mutation could explain several distant genomic duplications including some of the ones that took place during recent human evolution.

中文翻译：

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环状DNA中间体在人类大片段复制中的产生。

大的基因组片段的重复提供了基因组进化的遗传多样性。尽管它们很重要，但是如何产生这些重复仍然不确定，特别是对于遥远的重复基因组片段。在这里，我们提供了环状DNA中间体参与某些大型人类节段重复的单代证据。重复段之间从AB / CD到BA / DC的序列顺序的特定还原，以及在进化断点处仅存在微同源性和短indels，表明供体祖先基因座已被环化，并与受体基因座发生了偶然的复制性相互作用。这种新颖的随机基因组突变机制可以解释几个遥远的基因组重复，包括最近人类进化过程中发生的一些重复。