Huntington's Disease Research Today is a free monthly online journal that collates and summarizes the latest research about Huntington's Disease, including details on genetics, causes, symptoms, treatment.

Verification of somatic CAG repeat expansion by pre-PCR fractionation.

Hunter JM, Crouse AB, Lesort M, Johnson GV, Detloff PJ

Department of Cell Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.

The inheritance of a long CAG repeat causes several late onset neurological disorders including Huntington's disease (HD). Longer CAG repeats correlate with earlier onset of HD suggesting an increased toxicity for the products of long repeat alleles. PCR based data has been used to show that HD CAG repeat expansion beyond the inherited length occurs in affected tissues indicating a possible role for somatic instability in the disease process. PCR, however, is prone to artifacts resulting from expansion of repeat sequences during amplification. We describe a method to distinguish between CAG repeat expansions that exist in vivo and those that potentially occur during PCR. The method involves size fractionation of genomic restriction fragments containing the expanded repeats followed by PCR amplification. The application of this method confirms the presence of somatic expansions in the brains of a knock-in mouse model of HD.

Published 25 April 2005 in J Neurosci Methods, 144(1): 11-7.
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