A substitution corresponding to a human disease-associated mutation that result in the amino acid substitution of methionine for threonine at position 5 (T5M) was created and downstream of the gene a construct containing an IRES, lacZ with a nuclear localization signal, and an FRT-flanked neo cassette was inserted. Flp-mediated recombination removed the neo cassette. Reduced protein expression was confirmed by western blot analysis. (J:166362)