title: Novel mutations in the BHD gene and absence of loss of heterozygosity in fibrofolliculomas of Birt-Hogg-Dubé patients.
abstract: Birt-Hogg-Dubé (BHD) syndrome is an autosomal-dominantly inherited cancer syndrome characterized by fibrofolliculomas, lung cysts leading to pneumothorax, and chromophobic/oncocytic renal cell carcinoma. The disease is caused by heterozygous mutations in the BHD gene encoding folliculin and all mutations reported putatively lead to protein truncation. Although the function of folliculin is unknown, it is thought to be a tumor suppressor, with loss of heterozygosity (LOH) initiating tumor formation. Here, we report on four novel BHD gene mutations, including two splice-site mutations, in patients presenting with skin lesions only. We further show that LOH cannot be detected in fibrofolliculomas from three patients, suggesting that for the manifestation of cutaneous tumors in BHD syndrome haplo-insufficiency of folliculin is sufficient to initiate uncontrolled growth. Renal microscopic oncocytosis in BHD is considered as a precursor to malignant kidney tumors and may likewise be the result of haplo-insufficiency, with somatic second-hit mutations or LOH giving rise to malignancy later in life.
authors.affiliation: Department of Dermatology, University Hospital Maastricht, Maastricht, The Netherlands. mvst@sder.azm.nl
authors.forename: Maurice A M
authors.initials: MA
authors.lastname: van Steensel
authors.forename: Valerie L R M
authors.initials: VL
authors.lastname: Verstraeten
authors.forename: Jorge
authors.initials: J
authors.lastname: Frank
authors.forename: Nicole W J
authors.initials: NW
authors.lastname: Kelleners-Smeets
authors.forename: Pamela
authors.initials: P
authors.lastname: Poblete-Gutiérrez
authors.forename: Dominique
authors.initials: D
authors.lastname: Marcus-Soekarman
authors.forename: Reno S
authors.initials: RS
authors.lastname: Bladergroen
authors.forename: Peter M
authors.initials: PM
authors.lastname: Steijlen
authors.forename: Michel
authors.initials: M
authors.lastname: van Geel
mesh_terms: D000328:Adult; D000368:Aged; D002292:Carcinoma, Renal Cell / Q000175:diagnosis / Q000235:genetics*; D005260:Female; D006201:Hair Diseases / Q000175:diagnosis / Q000235:genetics*; D006801:Humans; D007680:Kidney Neoplasms / Q000175:diagnosis / Q000235:genetics*; D019656:Loss of Heterozygosity; D008171:Lung Diseases / Q000175:diagnosis / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009386:Neoplastic Syndromes, Hereditary / Q000175:diagnosis* / Q000235:genetics; D011506:Proteins / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D012878:Skin Neoplasms / Q000175:diagnosis / Q000235:genetics*; D025521:Tumor Suppressor Proteins / Q000235:genetics*
chemical_list: C476078:FLCN protein, human; D011506:Proteins; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins