 To monitor the editing activity, a PCR of the target area amplifies both alleles and, if one contains an insertion, deletion, or mutation, it results in a heteroduplex single-strand bubble that cleavage assays can easily detect.ZFNs have also been used to modify disease-causing alleles in triplet repeat disorders.Expanded CAG/CTG repeat tracts are the genetic basis for more than a dozen inherited neurological disorders including Huntington's disease, myotonic dystrophy, and several spinocerebellar ataxias.