Four novel cystic fibrosis mutations in splice junction sequences affecting the CFTR nucleotide binding folds

Single cases of the four novel splice site mutations 1525-1 G-->A (intron 9), 3601-2 A-->G (intron 18), 3850-3 T-->G (intron 19), and 4374 + 1 G-->T (intron 23) were detected in the CFTR gene of cystic fibrosis patients of Indo-Iranian, Turkish, Polish, and German descent. The nucleotide substitutions at the +1, -1, and -2 positions all destroy splice sites and lead to severe disease alleles associated with features typical of gastrointestinal and pulmonary cystic fibrosis disease. The 3850-3 T-to-G change was discovered in a very mildly affected 33-year-old delta F508 compound heterozygote, suggesting that the T-to-G transversion at the less conserved -3 position of the acceptor splice site may retain some wildtype function.