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SAM

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==== What is a CIGAR? ====
You may have heard the term CIGAR, but wondered what it means. Hopefully this section will help clarify it.
 
The sequence being aligned to a reference may have additional bases that are not in the reference or may be missing bases that are in the reference. The CIGAR string is a sequence of of base lengths and the associated operation. They are used to indicate things like which bases align (either a match/mismatch) with the reference, are deleted from the reference, and are insertions that are not in the reference.
 
For example:
RefPos: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Reference: C C A T A C T G A A C T G A C T A A C
Read: ACTAGAATGGCT
Aligning these two:
RefPos: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Reference: C C A T A C T G A A C T G A C T A A C
Read: A C T A G A A T G G C T
If the two align as above, you get:
POS: 5
CIGAR: 3M1I3M1D5M
 
The POS indicates that the read aligns starting at position 5 on the reference.
The CIGAR says that the first 3 bases in the read sequence align with the reference. The next base in the read does not exist in the reference. Then 3 bases align with the reference. The next reference base does not exist in the read sequence, then 5 more bases align with the reference. Note that at position 14, the base in the read is different than the reference, but it still counts as an M since it aligns to that position.
 
== Example SAM ==

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