Clinical genetics
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Birt-Hogg-Dubé syndrome (BHDS) is characterized by a clinical triad including cutaneous hamartomas originating from hair follicles, lung cysts/pneumothorax, and kidney tumors. Inactivating mutations of the tumor suppressor gene FLCN are identified in most families with BHDS. Usually, patients are referred for genetic examination by dermatologists because of the presence of typical multiple skin tumors with or without additional symptoms. ⋯ Typical cutaneous lesions were present only in 8 of 21 FLCN mutation carriers aged >20 years identified in the mutation-positive families. In addition, we provide clinical and molecular evidence that parotid oncocytoma, so far reported in six BHDS cases, is associated with this condition, based on the observation of a patient with bilateral parotid involvement and marked reduction of the wild-type FLCN allele signal in tumor DNA. Overall, the results obtained in this study contribute to the definition of the phenotypic characteristics that should be considered for BHDS diagnosis and FLCN mutation testing.