Identification of a cystic fibrosis mutation: deletion of isoleucine506.

The recent isolation of the cystic fibrosis (CF) gene has resulted in the identification of a common mutation (delta F508) that is found on about 70% of CF chromosomes and that comprises a deletion of 3 bp and results in the omission of Phe508 from within a putative ATP-binding domain of the predicted gene product. We describe a CF mutation that involves the deletion of 3 bp encoding Ile506 or Ile507. This is a rare mutation found in less than 1% of CF chromosomes and could be mistaken for delta F508 using the current methods for the molecular diagnosis of CF.