Relatively high prevalence of the CFTR mutations, G85E and 1154insTC

In the 5 one half years since the gene for cystic fibrosis (CF) was cloned (Kerem et al., 1989), more than 500 disease-causing mutations have been reported to the Cystic Fibrosis Genetic Analysis Consortium. Since an overwhelming proportion of the described mutations are rare or even unique, most clinical laboratories have limited their mutation screening panels to the mutations of greatest prevalence in their study populations. While cost-effective, this approach leaves 15-20% of CF alleles uncharacterized in most populations (Cystic Fibrosis Genetic Analysis Consortium, 1994). At the University of North Carolina Hospitals' Molecular Genetics Laboratory, we have screened 1,238 CF chromosomes of predominantly American Caucasian origin for a minimum of 20 mutations. Our rate of mutation characterization (81.5%) is comparable to that reported worldwide and for the United States. We report two mutations that are relatively common in our patient population but rarely included in routine screening panels elsewhere. First, we have detected the exon 7 frameshift mutation, 1154insTC, in six unrelated CF patients for an overall frequency of similar to 0.5% in our study population. Second, as reported by Kerem et al. (1994), we have found that the mutation G85E, commonly associated with pancreatic symptoms.