Heterogeneous spectrum of CFTR gene mutations in Korean patients with cystic fibrosis

Background: Cystic fibrosis (CF) is one of the most common hereditary disorders among Caucasians. The most common mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene have been well established among Caucasian populations. In Koreans, however, there are very few cases of genetically confirmed CF thus far, and the spectrum of mutations seems quite different from that observed in Caucasians.

Methods: In the present study, we describe the cases of 2 Korean CF patients, present sequencing results identifying mutations in their CFTR gene, and summarize the results of CFTR mutational spectrum from previously reported Korean CF patients. The mutations described were identified by performing direct sequencing analysis of the complete coding regions and flanking intronic sequences of the CFTR gene, followed by multiplex ligation-dependent probe amplification (MLPA) analysis in order to detect gene deletions or duplications that could not be identified by a direct sequencing method.

Results: Three CFTR mutations were identified in the 2 patients, including p.Q98R, c.2052delA, and c.579+5G>A. In an analysis of 9 Korean CF patients that included the 2 patients presented in this study, p.Q98R mutation was the only recurrently observed mutation with a frequency of 18.8% (3/16 alleles). Furthermore, only one of the mutations (c.3272-26A>G) was found among the 32 common mutations in the screening panel for Caucasians from the Cystic Fibrosis Mutation Database.

Conclusions: Sequencing of the entire CFTR gene followed by MLPA analysis, rather than using the targeted sequencing-based screening panel for mutations commonly found in Caucasian populations, is recommended for genetic analysis of Korean CF patients.