GENEALOGY-DNA-L Archives

From: "pwreed" <>
Subject: Re: [DNA] Y Chromosome less than half sequenced?
Date: Sat, 1 Mar 2003 21:48:33 -0000
References: <169.1b5943a8.2b916192@aol.com>

----- Original Message -----
From: <>
> While I was poking around looking for background material on Y
chromosome
> SNPs, I noticed that less than half of the Y chromosome has even
been
> sequenced! They may have fragments which haven't been located on the
> chromosome, but the "contig" sequences (contiguous or connecting
without a
> break) have big gaps.

Ann
You may be referring to the approximate half of the Y chromosome that
is Heterochromatin.

According to the human sequence paper of 2001 in Nature (Table 8) The
Y chromosome sequence (NRY?) comprises 21.8Mb of sequence, 0.1Mb of
gap and 27Mb of Heterochromatin.

I'm no expert on chromosome structure but a definition of
Heterochromatin I found states: "Contains mostly short repetitive
sequences. Its function is unknown. Is difficult to clone and probably
impossible to sequence"

So, it looks as much of the q arm of the chromosome is "junk" in the
full sense and of no relevance to genealogy or population genetics. I
assume that all the Y markers are in the sequenced region, ie between
p11 and q11.

Please note list readers who have got lost in the technicalities, this
discussion has no bearing on your Y chromosome results.

Peter

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