Abstract: The present invention relates to the field of genetic screening. More specifically, the described embodiments concern methods to screen multiple samples, in a single assay, for the presence or absence of mutations or polymorphisms in a plurality of genes. Approaches to screen for the presence or absence of mutations that are associated with cystic fibrosis and approaches to design primers that generate extension products that facilitate the resolution of multiple extension products in a single lane of a gel or in a single run on a column are also provided.