Is a repeat polymorphic?

Nick Jacobsen jacobsen at
Tue Jun 10 08:29:35 EST 1997

   The length of the repeat does matter. e.g. generally speaking for CA 
repeats they should at least 12 repeats long if they are to have a chance 
of being polymorphic. Obviously this is the lowest limit and longer 
repeats will have a increasing chance of being polymorphic and the longer 
they are the better heterozygosity value you can get. The sequence of the 
repeat should be perfect i.e. uninterupted by any imperfections. Imperfect 
repeats (see SCA2) are not good substrates for replication slippage and 
hence tend to be unpolymorphic.

ideally to summarise:

12 or more uninterupted repeat units and you are in with a chance!

hope this helps


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