NovaSeq 測序儀更改了堿基質(zhì)量打分的方法,詳見下面文章
https://www.illumina.com/content/dam/illumina-marketing/documents/products/appnotes/novaseq-hiseq-q30-app-note-770-2017-010.pdf
所以,下機(jī)fastq文件里堿基質(zhì)量長下面這樣,只有F,,,:三種符號,一般堿基質(zhì)量都是用ASCII字符表表示的。這三種符號通過查表可以看出分別代表77,58,44數(shù)值,而 -phred33 方法要求再減去33,所以三種符號代表的堿基質(zhì)量為37,25,11.
F,FFFFFFFFFFFFFFF,FFFFFFFFFFFFFFFFFFFFFFFFFFF:FF:FFFFFFFFFFFFFF,FF:FF,F,FFFFFFFFFFFFFFFFFFFFFFFFFF,FFFFFFFFFFFFFFFFFFFFFFF:F:FFF:FFF:FFFFFFFF:F::FFFFF

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