Qualité des lectures

Figure 1 : average quality of readings for each sample before filtering.

Source : SAREK example MultiQC Nextflow/nf-core

In Figure 1, the position of the reads is shown on the x-axis and the average quality of the readings on the y-axis. The 2 samples are shown in the graph, but they overlap.

We can see 2 things: that for the first and last nucleotides, quality is lower than for the rest of the bases, and that quality decreases as we move towards the 5' end. This is a common occurrence, so don't be too careful. Qualities below 30 can be problematic and will surely be trimmed.

Figure 2 : average quality of readings for each sample after filtering.

Source : SAREK example MultiQC Nextflow/nf-core

We can clearly see that there is no great evolution after filtering, which means that the sequencing went well and the data quality is high.