In BHD syndrome, familial primary spontaneous pneumothorax was observed,[8] and in a large sample family survey of BHD syndrome by Schmidt et al, 32% of patients had a history of spontaneous pneumothorax, and 85% had bullosa found on CT.[9] Painter reported a genetic diagnosis of BHD syndrome in a family with a history of spontaneous pneumothorax in 24% of the patients and bullosa in 54% of the families.[10] The discovery of the FLCN gene is a big step forward in the study of the genetic mechanisms underlying primary spontaneous pneumothorax. This evidence concerns the gene FLCN and familial spontaneous pneumothorax.