FLCN and Birt-Hogg-Dubé syndrome: In 2002, Nickerson et al first reported susceptible pathogenic genes for BHD syndrome, namely FLCN gene.[5] A large number of molecular biological experiments have found that there are 14 exons in the FLCN gene, and the mutation sequence in the patient in this study was located in exon 13.[6,8,12] BHD syndrome is a rare autosomal dominant inherited disorder.