title: Where Birt-Hogg-Dubé meets Cowden syndrome: mirrored genetic defects in two cases of syndromic oncocytic tumours.
abstract: Birt-Hogg-Dubè (BHD) is an autosomal dominant syndrome characterised by skin fibrofolliculomas, lung cysts, spontaneous pneumothorax and renal cancer. The association of benign cutaneous lesions and increased cancer risk is also a feature of Cowden Syndrome (CS), an autosomal dominant disease caused by PTEN mutations. BHD and CS patients may develop oncocytomas, rare neoplasias that are phenotypically characterised by a prominent mitochondrial hyperplasia. We here describe the genetic analysis of a parotid and a thyroid oncocytoma, developed by a BHD and a CS patient, respectively. The BHD lesion was shown to maintain the wild-type allele of FLCN, while losing one PTEN allele. On the other hand, a double heterozygosity for the same two genes was found to be the only detectable tumorigenic hit in the CS oncocytoma. Both conditions occurred in a context of high chromosomal stability, as highlighted by comparative genomic hybridisation analysis. We conclude that, similarly to PTEN, FLCN may not always follow the classical Two Hits model of tumorigenesis and may hence belong to a class of non-canonical tumour suppressor genes. We hence introduce a role of PTEN/FLCN double heterozygosity in syndromic oncocytic tumorigenesis, suggesting this to be an alternative determinant to pathogenic mitochondrial DNA mutations, which are instead the genetic hallmark of sporadic oncocytic tumours.
authors: Dip. Sc. Mediche e Chirurgiche-DIMEC, U.O. Genetica Medica, Policlinico Universitario S.Orsola-Malpighi, Bologna, Italy.
authors: Laura Maria
authors: LM
authors: Pradella
authors: Martin
authors: M
authors: Lang
authors: Ivana
authors: I
authors: Kurelac
authors: Elisa
authors: E
authors: Mariani
authors: Flora
authors: F
authors: Guerra
authors: Roberta
authors: R
authors: Zuntini
authors: Giovanni
authors: G
authors: Tallini
authors: Alan
authors: A
authors: MacKay
authors: Jorge S
authors: JS
authors: Reis-Filho
authors: Marco
authors: M
authors: Seri
authors: Daniela
authors: D
authors: Turchetti
authors: Giuseppe
authors: G
authors: Gasparre
mesh_terms: D018249:Adenoma, Oxyphilic / Q000235:genetics*; D000483:Alleles; D058249:Birt-Hogg-Dube Syndrome / Q000235:genetics*; D063646:Carcinogenesis / Q000235:genetics; D043171:Chromosomal Instability; D006223:Hamartoma Syndrome, Multiple / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D008297:Male; D051059:PTEN Phosphohydrolase / Q000235:genetics; D010307:Parotid Neoplasms / Q000235:genetics; D020641:Polymorphism, Single Nucleotide; D011518:Proto-Oncogene Proteins / Q000235:genetics; D013964:Thyroid Neoplasms / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000235:genetics
chemical_list: C476078:FLCN protein, human; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human
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