A simple and precise diagnostic method for spinal muscular atrophy using a quantitative SNP analysis system

A simple and precise diagnostic method for spinal muscular atrophy (SMA) using high-resolution CE-based single-strand conformation polymorphism (CE-SSCP) was developed in this study. SMA is a common genetic disorder caused by an abnormality in the relative copy numbers of SMN1 and its centromeric copy SMN2, which differ only in two nucleotides, namely at exons 7 and 8. Therefore, the precise discrimination of the differences in sequence as well as their relative quantities is crucial for the diagnosis of SMA. Multiplex ligation-dependent probe amplification and sequence-sensitive DNA separation using hydroxyethyl cellulose and hydroxypropyl cellulose blended polymer matrix are currently the available methods used in the diagnosis of SMA. However, these methods are limited by their extended hybridization step and low resolution. In this study, the simultaneous discrimination of SMN exons 7 and 8 was successfully demonstrated using high-resolution CE-SSCP. Unlike the previously reported alternative method, single base differing amplicons were baseline-separated because of its extraordinary resolution, thus providing accurate and precise quantification of each paralog.