Prevalence of Birt-Hogg-Dubé Syndrome Among Patients With (Hereditary) Spontaneous Pneumothorax

Based on the results of the pilot study in VUmc *Free University Medical Center), in which 3 out of 40 tested patients had a pathological FLCN mutation, the investigators decided to extend the study to a second center; Rijnstate Hospital Arnhem. In this hospital a retrospective search was performed; patients who were treated for primary spontaneous pneumothorax were included. In the dossiers the investigators searched for medical history, pneumothorax side and recurrence, diagnostic imaging, treatment, co-morbidity, complications of treatment, skin abnormalities, kidney disease, smoking behavior, medication, and familial incidence of pneumothorax and other diseases. Patients will receive a letter with explanation of the research and a questionnaire in which the investigators ask them their about the medical status, co-morbidity, pneumothorax (number and side), smoking behavior, use of drugs, familial incidence of pneumothorax and other diseases.

The population will be formed out of patients who have returned the fully filled in questionnaire and who have given permission to receive information for further research. This further information will consist of an information letter on BHD syndrome and a consent form for a one-time visit to the out-patient clinic of Rijnstate hospital. Investigators expect that about 200 patients will return the fully filled in questionnaire and give their consent for further research. In a one-time visit in out-patient clinic, there will be given personal information on BHD syndrome and there will be performed physical examination for finding fibrofolliculomas. A pulmonary CT scan for evaluation of presence of lung cysts will be performed. Two samples of venous blood will be collected to access information on DNA diagnostics for pathogenic FLCN mutations. These are associated with the BHD syndrome. This last diagnostic testing will be performed in VUmc (Vrije Universiteit medisch centrum or Free University Medical Centre).