According to Table 7, the top 10 keywords with the highest frequency in 2001–2021 are Birt-Hogg-Dubé syndrome (347), spontaneous pneumothorax (168), mutation (159), renal cell carcinoma (119), family (83), folliculin (83), BHD gene (68), tumor (67), cancer (66), fibrofolliculoma (66). This evidence concerns the gene FLCN and pneumothorax.