Mass screening for cystic fibrosis heterozygotes: two assay systems compared.

Two different assay systems were used to detect mutant cystic fibrosis alleles in mouthwash samples from pregnant women attending antenatal clinics. In the first phase of the study, comprising 3110 consecutive samples, we compared the performance of an in-house system and a commercial amplification refractory mutation system (ARMS). Successful analyses were completed at first attempt in approximately 90% of samples, and the patient resampling rate was 1.1%. There were no false positives and only one detected false negative. In the second phase, comprising 3333 consecutive samples, only ARMS was used. Again, there were no false positives and the patient resampling rate dropped to 0.5%. On the basis of convenience and reduced operator time, we have elected to use ARMS for further screening for cystic fibrosis heterozygotes.