A new complex allele of the CFTR gene partially explains the variable phenotype of the L997F mutation.

Purpose: To evaluate the role of complex alleles, with two or more mutations in cis position, of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in the definition of the genotype-phenotype relationship in cystic fibrosis (CF), and to evaluate the functional significance of the highly controversial L997F CFTR mutation.

Methods: We evaluated the diagnosis of CF or CFTR-related disorders in 12 unrelated subjects with highly variable phenotypes. According to a first CFTR mutational analysis, subjects appeared to be compound heterozygotes for a classic mutation and the L997F mutation.

A 96-well formatted method for exon and exon/intron boundary full sequencing of the CFTR gene.

Full genotypic characterization of subjects affected by cystic fibrosis (CF) is essential for the definition of the genotype-phenotype correlation as well as for the enhancement of the diagnostic and prognostic value of the genetic investigation. High-sensitivity diagnostic methods, capable of full scanning of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, are needed to enhance the significance of these genetic assays. A method for extensive sequencing of the CFTR gene was optimized.