Phenotypic manifestations of the CFTR c.3140-16T>A (3272-16T>A) variant in homozygous state in a child with cystic fibrosis

We report a case of cystic fibrosis (CF) in a 9-year-old child with the rare c.3140-16T>A (3272-16T>A) variant of the CFTR gene in homozygous state. CF was suspected at neonatal screening. The results of the sweat test (Nanoduct) were 88 and 84 mmol/L. Since the age of 1.5 months, the patient received inhalation of dornase alfa, kinesitherapy, pancreatic enzymes (only in case of abundant intake of fatty foods), and vitamin therapy. The boy early developed cough with sputum; at the age of 5 years, he also developed chronic sinusitis. At the age of 3 years, his level of fecal pancreatic elastase 1 was 597 μg/g, which indicated preserved exocrine function of the pancreas. At the age of 9 years, the boy demonstrated normal physical development and lung function (examined using spirometry). Computed tomography showed no bronchiectasis. X-ray revealed radiological signs of chronic sinusitis. The assessment of intestinal current measurement (ICM) demonstrated a reduced CFTR function typical of mild genetic variants. Thus, the patient with the c.3140-16T>A (3272-16T>A) variant in homozygous state has developed only chronic rhinosinusitis by the age of 9 years. Measurement of ICM confirmed the diagnosis of mild CF genotype. Key words: c.3140-16T>A (3272-16T>A) genetic variant, cystic fibrosis, mild phenotype