The protein truncation test (PTT) as a method of detection for choroideremia mutations

The predominance of truncative mutations responsible for choroideremia (CHM) led us to investigate the use of the protein truncation test (PTT) applied to lymphocyte RNA derived from affected males as a scanning method. The entire CHM coding region was reversed-transcribed in three overlapping cDNA segments (RT-PCR) which were amplified and further analysed by PTT after in vitro transcription/ translation. This strategy enabled us to detect the CHM-causative alteration in each of the four unrelated patients from southern France who were investigated. We describe three novel mutations (E177X, 323delT, 1313delTC), and report one recurrent mutation (R267X) in CHM. We believe this to be the first attempt at applying RT-PCR-PTT to CHM mutation detection.