FLCN and Birt-Hogg-Dubé syndrome: Also, decreased expression of the FLCN mRNA may lead to BHD.<h4>Conclusion</h4>BHD syndrome can present with a negative FLCN gene mutation; however, patients must meet the known diagnostic criteria such as criteria made by Menko <i>et al</i>., Gupta <i>et al</i>., and Schmidt <i>et al</i>.