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Isaac aligner V4 genome aligner questions

1) For the alignment of the human whole exome sequence FASTq data to the human GRCh38p14 reference genome, and using the Isaac aligner V4, do you recommend:

unmasked genome reference ?
masked genome reference ?
reference with hs38d1 decoy sequence included ?

2) Please define how the human reference genome sequences should be masked for the best use with Isaac aligner V4 and human exome FASTq data ?

is it a soft mask ?
is it a hard mask ?

3) Please define how the human reference genome sequences should be masked for the best use with Isaac aligner V4 and human whole genome FASTq data ?

is it a soft mask ?
is it a hard mask ?

4) For the alignment of the human whole genome sequence FASTq data to the human GRCh38p14 reference genome, and using the Isaac aligner V4, do you recommend:

unmasked genome reference ?
masked genome reference ?
reference with hs38d1 decoy sequence included ?

5) To mark and remove PCR duplicates from the BAM file generated from either human exome or human whole genome FASTA, what parameters are set with Isaac aligner V4: Option A: --keep-duplicates 1 or --keep-duplicates 0 ....which one ?

OR Option 2: --mark-duplicates 1 or --mark-duplicates 0 ....which one ?

genome aligner bam

Isaac aligner is very fast compared to other aligners. The accuracy is comparably about the same as BWA-MEM.

That is true. However, Isaac's memory usage is over a dozen times higher (which isn't a problem given that a cheap modern refurbished server will give you >64 gb RAM).

Bwa is more widely used so you might have more community support if you use that.

there is no such thing as p14 in the context of alignment to a reference genome (the patches play no role in that), but the decoy definitely is a thing. I think the decoy is a good idea, and masking is not. Mark duplicates.

1 answer

Thank you for the helpful comments.

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