NONISOTOPIC METHOD FOR ACCURATE DETECTION OF (CAG)(N) REPEATS CAUSINGHUNTINGTON DISEASE

Huntington disease (HD) is a neurodegenerative disorder caused by an e xpanded trinucleotide repeat (GAG), located at the 5' end of the novel IT15 gene. Discovery of this expansion allows the molecular diagnosis of HD by measuring repeat length. We applied a simple nonisotopic met hod to detect (GAG)(n) repeats, avoiding both radioactive and Southern transfer analysis. The assay is based on direct visualization of elec trophoresed PCR products, after silver nitrate gel staining. Its accur ate sizing of HD alleles allows presymptomatic diagnosis of at-risk pe rsons. By avoiding isotopic manipulations, the method is safe and accu rate, with no radioactive background bands. Furthermore, because it pe rmits direct allele visualization after gel staining, the method is si mple and rapid, allowing allele sizing within hours rather than days.