centiMorgans & physical distance: a question.

Paul Linehan linehan at ceph.cephb.fr
Wed Aug 30 03:38:55 EST 1995


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BACKGROUND: 
     Most descriptions of chromosomal length are based upon the
concept of centiMorgans, a notion derived from rates of
recombination. These descriptions usually do not mention physical
length. However, at least one text provides a statement suggesting
that, regarding human chromosomes, centiMorgan length tends to
correspond to physical length. 
       "Thus, one can think of centiMorgans as a rough unit of
distance along the chromosome, although the relation to physical
distance is not truly linear because regions vary somewhat in
recombination potential." p204, Principles of Medical Genetics;
Gelehrter and Collins, 1990.
       I have accumulated approximately 40 articles wherein
chromosome length is reported and wherein male/female length
differences are reported in terms of centiMorgans. 
       
QUESTION: 
     Is the Gelehrter and Collins quote accurate? In other words,
although not precisely linear, does physical length tend to
correspond to centiMorgan length?

CONCLUSION:
     I would appreciate receiving comments, anecdotes, and citations
that help answer my "centiMorgan versus physical-length" question.

                  **************       *************

Thank you,

Teresa C. Binstock, Researcher
Teresa.Binstock at UChsc.edu


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This sort of question would perhaps be better in bionet.molbio.gene-linkage.
As for the answer to the question it is yes. One further point though. Not
only are there male/female differences (the female map is usually longer)
but this is not a uniform phenomenon, i.e. there are areas of the genome
where the male map is longer. The answer to the question remains yes.. it 
just depends what sort of approximations you wish to make!

Regards.


Paul...





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