Nucleic Acids Research, 2002, Vol. 30, No. 16 e83
© 2002 Oxford University Press
Counting CAG repeats in the Huntington’s disease gene by restriction endonuclease EcoP15I cleavage
Institute of Virology, Humboldt University Medical School (Charité), D-10098 Berlin, Germany, 1 Max Planck Institute for Molecular Genetics, D-14195 Berlin, Germany and 2 Max-Delbrueck Center for Molecular Medicine, D-13092 Berlin, Germany
*To whom correspondence should be addressed. Tel: +49 30 450 525 092; Fax: +49 30 450 525 907; Email: detlev.kruger{at}charite.de
The authors wish it to be known that, in their opinion, the first two authors should be regarded as joint First Authors
Huntington’s disease (HD) is a progressive neurodegenerative disorder with autosomal-dominant inheritance. The disease is caused by a CAG trinucleotide repeat expansion located in the first exon of the HD gene. The CAG repeat is highly polymorphic and varies from 6 to 37 repeats on chromosomes of unaffected individuals and from more than 30 to 180 repeats on chromosomes of HD patients. In this study, we show that the number of CAG repeats in the HD gene can be determined by restriction of the DNA with the endonuclease EcoP15I and subsequent analysis of the restriction fragment pattern by electrophoresis through non-denaturing polyacrylamide gels using the ALFexpress DNA Analysis System. CAG repeat numbers in the normal (30 and 35 repeats) as well as in the pathological range (81 repeats) could be accurately counted using this assay. Our results suggest that this high-resolution method can be used for the exact length determination of CAG repeats in HD genes as well as in genes affected in related CAG repeat disorders.