Birt-Hogg-Dubé Syndrome Caused by a Novel Mutation in the FLCL Gene.

Background: Birt-Hogg-Dubé syndrome is a genetic disorder characterized by skin fibrofolliculomas, cystic lung disease, and bilateral renal tumors. It has also been implicated in the formation of tumors in other organs, particularly thyroid and colon. This case presents a young female presenting with only cystic lung disease and kidney tumors, identified as having a never before identified heterozygous mutation in the folliculin () gene which is the likely cause of her syndrome.

Case Presentation: A 34-year-old female was found to have bilateral renal masses, 2.4 cm on the right and 7.6 cm on the left, as well as multiple, small cysts in the lungs. Chest imaging further characterized the lung cysts as being basilar predominant with the largest measuring 1.6cm. The left kidney mass was resected with a partial nephrectomy with final pathologic diagnosis of an oncocytoma. Genetic testing was undertaken as she did not have characteristic skin findings. A previously undescribed mutation in the gene (c.780-2A>G) was identified with no matches in the human genetic mutation database (HGMD). Review of that database identified over 160 separate mutations in the gene. Extensive history did not identify any family members who had similar disease processes suggesting that this could be a spontaneous mutation in the proband.

Conclusions: This case highlights that the traditional view of Birt-Hogg-Dubé syndrome as having a strong familial component may be incorrect and that spontaneous mutation may be more common than previously thought. Also notable is the fact that this patient had no characteristically described fibrofolliculomas that traditionally are the hallmark of the condition. This case suggests that genetic testing should be obtained in all suspected cases of Birt-Hogg-Dubé syndrome as the patient may not present with the typical skin findings and may also present with no family history consistent with this disorder.