Cystic fibrosis transmembrane conductance receptor (CFTR)-related disease is diagnosed in patients affected by CFTR dysfunction but who do not fully meet the CF diagnostic criteria. Only 2% of all CF patients have CFTR-related disease. We define the demographic characteristics of such patients, perform mutational analyses, and describe the clinical findings.
Twenty-four patients were followed-up in terms of CFTR-related disease. Patients with CF symptoms but who did not completely fulfil the CF diagnostic criteria were enrolled. Age, body mass index (BMI) at the times of diagnosis and admission, symptoms, pulmonary function and fecal elastase test results, gene analyses, and clinical findings during follow-up, were evaluated.
Ten patients (42%) were female and 14 (58%) male, of mean age 15.3 years (min-max 6-20 years). The mean age at diagnosis was 8.5 years (min-max 3-14 years) and the most common presenting complaint was a cough (n=19). During follow-up, chronic sinusitis developed in 15 patients, bronchiectasis in 13, nasal polyposis in six, failure to thrive in three, recurrent pancreatitis in two, asthma in one, and congenital bilateral absence of the vas deferens (CBAVD) in one. Fecal elastase levels were low in only one of the three patients who failed to thrive. In terms of CFTR gene mutations, two were found in 10 patients, one in eight patients, and none in six.
CFTR-related disease presents with various clinical findings. Serious symptoms may develop later in life. Late diagnosis significantly compromises the quality and duration of life in such patients.

© 2020 Japan Pediatric Society.