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I am not a biologist. But need some genetic data. So I searched internet and reached NCBI's website. I came to know from the FAQ page that I can the complete genome data of organisms from So I went to the FTP site and opened the homosapien section I found folders CHR_1 to CHR_22, CHR_MT,CHR_Un, CHR_X and CHR_Y.

My doubt is this : Normally there are only 23 pair chromosomes right? 1 to 22 pairs OK. XY make another pair. Then what are MT and Un ?

And the folder which I am looking is a genome of male right?

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up vote 3 down vote accepted

chr_MT: List of variations that map to the mitochondria

chr_Multi.txt.gz: List of variations that map to multiple chromosomes

chr_UN: List of mapped variations that are on unplaced chromosomes

see here for more information.

This is the reference genome for human, as far as I know there is no discrimination for it into male/female.

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If it was female genome , do we have to consider X twice. – dexterdev May 7 '14 at 12:23
@terdon : Do you mean the AGTC sequences as 'List of variations'? – dexterdev May 8 '14 at 2:02
@dexterdev I did not answer this, Chris did. I just edited which is why you see my name there. I don't know what Chris meant by that since I can't find that file on the FTP site nor see it mentioned in the FTP's README (which, by the way, you should read). – terdon May 8 '14 at 2:06
OK @terdon I will read it. – dexterdev May 8 '14 at 2:10
@dexterdev "List of variations" simply means variations from the reference sequence. – Chris May 8 '14 at 7:10

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