Correlación genotipo fenotipo de un grupo de pacientes con fibrosis quística / Correlation between phenotype and genotype in a group of patients with cystic fibrosis

RESUMO

Background: Cystic fibrosis (CF) is the most common lethal autosomic disease in Caucasians, with a global incidence of 13000 newborns. More than 900 mutations have been described, involving the Cystic Fibrosis Transmembrane Regulator (CFTR). The ÆF508 mutation is present in 60 percent of alleles studied worldwide. Aim: To report 25 patients with cystic fibrosis in whom a genetic study was done. Material and methods: Twenty five patients (14 men, aged between 18 months and 25 years) with a diagnosis of cystic fibrosis based on clinical features plus two abnormal sweat tests are reported. The genetic study considered the 20 most common mutations in cystic fibrosis and was done in genomic DNA of peripheral lymphocytes, by polymerase chain reaction. Results: A mutation was found in 75 percent of analyzed alleles. ÆF508 was present in 50 percent of cases (ÆF508/ÆF508 in 8 and ÆF508/other in 11). When ÆF508 was present, pancreatic insufficiency was always a feature and nutritional status was worse. Respiratory involvement was variable, both for homozygous and heterozygous cases. Other severe mutations such as W1282X and G542X were related to clinical manifestations similar to those found in ÆF508 mutation. Diagnosis was made before six months of age in 12 patients. The clinical presentation was meconium ileus and there was a family history of the disease in most cases. The majority of cases of early diagnosis presented severe mutations, but milder respiratory symptoms and lesser nutritional compromise at the time of assessment. Conclusions: Most patients studied had a severe cystic fibrosis mutation, which was associated with more severe respiratory, pancreatic and nutritional involvement. The early diagnosis of the disease, which would allow to improve the prognosis and the quality of life, must be emphasized