the present invention pertains to genetic screening methods and related cells and genetic constructs . in particular , the invention relates to a method of screening cells for an alteration , typically an amplification , in the copy number of a nucleic acid of interest using an amplifiable nucleic acid linked to a reporter nucleic acid ; a method of screening cells for increased expression of a polypeptide of interest derived from the nucleic acid of interest ; and related cells and genetic constructs . the method allows for high throughput screening of recombinant cells expressing a polypeptide or protein of interest and , in particular , for screening of cells expressing the polypeptide or protein of interest at elevated levels .