transcription-coupled repair|Germ|HK|TS|Mutation|四类变异

生命组学-可遗传变异

GC content：碱基：

GC content不同的植物对应的gene length，可看作上图的转置：

由GC content看出来碱基变异程度，可以找到对应碱基改变，所以gene expression也会相应改变，比如亲水到疏水。

转录偶联变异transcription-coupled repair

核苷酸切除修复(nucleotide excision repair)是一种DNA修复方法。[1]由于化学、辐射和很多其他因素的都会对DNA碱基对造成破坏，DNA时常需要修复。核苷酸切除修复是其中一种很重要的方法，通过移除绝大部分紫外线导致的DNA损伤，使得细胞免于受到有害变异的影响（主要形式为胸腺嘧啶二聚体及6,4-光产物）。其发现者，瑞典生物化学家托马斯·林达尔凭此获得2015年诺贝尔化学奖。

Housekeeping gene：In molecular biology, housekeeping genes are typically constitutive genes that are required for the maintenance of basic cellular function, and are expressed in all cells of an organism under normal and patho-physiological conditions.

Germ lineage 胚芽系可遗传变异：TCR：transcription coupled repair

Transcription结构：

Promoter是TATA box；Activator 与enhancer结合

HK (housekeeping)or TS(condition-related)通过图示来界定基因

The higher GC and CpG island content may indicate HK promoters are more stable than the TS promoters. HK genes with high density CpG islands have higher transcriptional activity across tissues, that is, it has a higher level of expression, while TS genes may be restricted by strict expression in specific tissue

HK gene有高CpG岛，tissue specific gene 与其相反，可以用于识别肿瘤。