Skip to content

测序质量分值

测序质量分值简介

测序质量分值用来评估碱基的错误检出率。利用边合成边测序(SBS)技术,read中的每个碱基会得到基于phred样算法1,2与最初为桑格测序实验开发的算法类似)的质量分值。

Sequencing Technology Video
测序技术视频

了解Illumina SBS如何工作。

Q值定义

指定碱基的测序质量分值Q是按照如下公式定义的:

 Q = -10log10(e)

其中e是预估的碱基错误检出率。

  • Q值高,说明错误率低。
  • Q值低,可能会导致不可用read的比例显著增高。还可能导致假阳性变异检出率增加,得出不正确的结论。

如下所示,20的质量分值代表了错误率为1/100,对应的检出准确率为99%。

SBS技术综述

Illumina技术对SBS测序化学进行了优化,支持大规模平行测序。

了解更多
测序质量分值与碱基检出精确度的关系
质量分值 碱基的错误检出率 推断的碱基检出精确度
10 (Q10) 1/10 90%
20 (Q20) 1/100 99%
30 (Q30) 1/1000 99.9%

Illumina测序质量分值

Illumina测序化学过程提供较高的精确度,绝大多数碱基得分在Q30及以上。这种精确度水平是多种测序应用的理想选择,包括临床研究。了解为何PhiX可以作为Illumina NGS运行中的质控品,进行运行质量监测。

Run Quality Monitoring

Learn what PhiX is and how it can be used as an in-run control for sequencing run quality monitoring in Illumina NGS.

Read Bulletin

有关质量分值的更多信息

关于测序质量分值的更多深度信息,请阅读如下技术说明:

Benefits of SBS Technology

Proven base-calling accuracy and uniform coverage enable robust base calling across the genome, giving you confidence in your results.

Learn More
Next-Generation Sequencing

Learn how NGS compares to conventional methods, how the technology works, and what it can do for you.

Choosing an NGS Company

Seek out a best-in-class NGS company with user-friendly bioinformatics tools and industry-leading support and service.

NGS Experimental Design

Learn about read length, coverage, and other experimental considerations to help you plan your sequencing run.

参考文献
  1. Ewing B, Hillier L, Wendl MC, Green P. (1998): Base-calling of automated sequencer traces using phred. I. Accuracy assessment. Genome Res. 8(3):175-185
  2. Ewing B, Green P. (1998): Base-calling of automated sequencer traces using phred. II. Error probabilities. Genome Res. 8(3):186-194