marker number??

Robyn Wallace rwallace at
Thu Jun 29 19:30:12 EST 1995

>what is an easy way to estimate the number of markers needed to map a 
>genome at a given interval.  i'm just looking for something quick and 
>dirty.  also, my advisor says that, theoretically, one chromosome arm 
>should equal 1 Morgan.  is this valid?  there are published linkage 
>groups out there that are over 100 cM!  that's 10 Morgans!  thanx in advance.

Morgans are distances calculated based on the recombination frequency
between two markers.  Each human chromosome is a different length, ranging
from ~350cM for chr 1 to ~70cM for chr 22.

Get a copy of the latest Genethon genetic linkage map (if you intend to use
PCR based maskers) Nature Genetics 7:246->.  Select markers around 20 cM
apart on the chromosome of interest.  These should be close enough to
ensure you dont miss any possible linkage (10 cM apart would be ideal, but
you are looking for a 'quick and dirty' method).  


Robyn Wallace
Department of Cytogenetics and Molecular Genetics         /\_/\
Womens and Childrens Hospital                            ( o o )
North Adelaide, South Australia  5006                     > - <
Ph  61 08 204 6442
Fax 61 08 204 7342
Email  rwallace at


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