With a view to assessing genotype-to-phenotype correlations in cystic fibrosis (CF), the clinical presentation of CF children from the United Arab Emirates (UAE) who were homozygous for cystic fibrosis transmembrane conductance regulator (CFTR) mutation S549R(T-->G was investigated. This mutation is localized in intron 11 (nucleotide binding domain 1 of the CFTR protein) and had so far been described as a private mutation only. The associations between the R549/R549 genotype and 20 outcome variables, including age at diagnosis, sweat chloride concentrations, growth percentiles, meconium ileus, pancreatic sufficiency, pulmonary disease, associated complications and micro-organism colonization were examined in a group of 15 CF children (9 females and 6 males). Mean current age and age at diagnosis were both low (5.4+/-3.5 and 1.0+/-1.1 yrs, respectively). Although none of the 15 CF patients had presented with meconium ileus at birth, all were pancreatic insufficient and had very severe lung disease, with a high rate of Pseudomonas aeruginosa and Staphylococcus aureus. Two patients died during the course of this investigation (one was 5 months and the other, 6 yrs old). The clinical presentation associated with S549R(T-->G) homozygosity in the United Arab Emirates is quite homogeneous and shows an extreme degree and course of cystic fibrosis severity.

Genotype-phenotype analyses in cystic fibrosis (CF) have shown that cystic fibrosis transmembrane conductance regulator (CFTR) genotypes can predict pancreatic status but that correlations with pulmonary status remain elusive. We investigated the extent and severity of lung disease associated with CFTR mutation S549R (T-->G). This mutation is localized in intron 11 (nucleotide-binding fold 1 of the CFTR protein) and had so far been described as a private mutation only. It is associated with an extremely severe overall CF phenotypic expression. Detailed radiological analyses were performed by a single observer in 12 children with CF from the United Arab Emirates who were homozygous for CFTR mutation S549R (T-->G). A diversity of pulmonary changes included marked hyperinflation in early infancy in conjunction with inflammation of the interstitium. After 2 years of age, signs of central airway involvement occurred in association with early signs of pulmonary hypertension. In conclusion, although there is some diversity in the radiological findings of these CF patients, R549 is a very severe allele associated with extreme lung disease and rapid pulmonary decline.