NovaSeq™ 6000 System Quality Scores and RTA3 Software - Illumina

NovaSeq 测序仪更改了碱基质量打分的方法,详见下面文章

https://www.illumina.com/content/dam/illumina-marketing/documents/products/appnotes/novaseq-hiseq-q30-app-note-770-2017-010.pdf
所以,下机fastq文件里碱基质量长下面这样,只有F,,,:三种符号,一般碱基质量都是用ASCII字符表表示的。这三种符号通过查表可以看出分别代表77,58,44数值,而 -phred33 方法要求再减去33,所以三种符号代表的碱基质量为37,25,11.

F,FFFFFFFFFFFFFFF,FFFFFFFFFFFFFFFFFFFFFFFFFFF:FF:FFFFFFFFFFFFFF,FF:FF,F,FFFFFFFFFFFFFFFFFFFFFFFFFF,FFFFFFFFFFFFFFFFFFFFFFF:F:FFF:FFF:FFFFFFFF:F::FFFFF

NovaSeq™ 6000 System Quality Scores and RTA3 Software - Illumina_第1张图片

F=70-33=37
:=58-33=25
,=44-33=11

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