The authors noted that pulmonary cysts and pneumothoraces were the most frequent presentation of BHD syndrome in these families, followed by fibrofolliculomas and then kidney cancer. However, it is important to note that this finding may reflect an ascertainment bias (as 7 families were diagnosed due to pneumothoraces and only 2 from kidney cancer). Genetic testing was then conducted to determine the FLCN mutations present in this cohort, and it was noted that there were 5 heterozygous mutation patterns (of which 3 have been previously described only in Japanese patients so far).

Histopathological analysis showed that the BHD-associated lung cysts were lined with differentiated pneumocytes and had alveolus-like structures within them, both of which could help differentiate BHD syndrome from other cystic lung conditions. Immunohistochemical analysis using a rabbit polyclonal antibody against full-length FLCN showed that the epithelial cells lining the cysts expressed FLCN, leading the authors to suggest that it could be haploinsufficient in these tissues. However, the possibility of a dominant negative mutation has not been discussed. When compared to controls, these cells also weakly expressed phosphorylated mTOR (p-mTOR, which is an active form of the protein) and strongly expressed phosphorylated ribosomal protein S6 (p-S6, which is an indicator of mTOR activation). Consequently, could deranged mTOR signalling play a role in the development of BHD lung cysts?

Furuya et al. also examined kidney tissues from these patients and saw that the tumour-free regions had cysts and oncocytic nodules. Additionally, immunostaining (using the same rabbit polyclonal FLCN antibody described above) showed that FLCN was expressed in the normal-looking tubules, as well as the cyst epithelial cells. In contrast, there were numerous FLCN-negative cells in the tumour tissue. Similarly, full-length FLCN was also visible in the normal-looking kidney tissue by western blot using the rabbit polyclonal FLCN antibody, but was almost undetectable in the BHD tumour sample. However, the presence of truncated forms of FLCN cannot be ruled out.

Furthermore, a large increase in p-S6 was observed by western blot in the BHD kidney tumour when compared to controls. This result suggests that mTOR is activated in BHD kidney tumours, which adds to the discussion regarding the functional role of FLCN in mTOR signalling (see here for more information). Moreover, FLCN haploinsufficiency may also be associated with this signalling pathway in both lung and kidney cysts, which could play a role in the initial stages of tumourigenesis in BHD syndrome.

• Furuya M, Tanaka R, Koga S, Yatabe Y, Gotoda H, Takagi S, Hsu YH, Fujii T, Okada A, Kuroda N, Moritani S, Mizuno H, Nagashima Y, Nagahama K, Hiroshima K, Yoshino I, Nomura F, Aoki I, & Nakatani Y (2012). Pulmonary cysts of Birt-Hogg-Dubé syndrome: a clinicopathologic and immunohistochemical study of 9 families. The American journal of surgical pathology, 36 (4), 589-600 PMID: 22441547

Byrne et al presented a patient diagnosed with BHD who was identified to have a renal angiomyolipoma. Renal angiomyolipomas are usually associated with tuberous sclerosis complex (TSC), rather than BHD. The authors highlighted the molecular overlaps between TSC and BHD.

To find out more, download the latest version of the database here.

Lindsay is part of the Urologic Oncology Branch at the NCI, which treats patients affected with inherited and sporadic forms of genitourinary cancer, and performs clinical trials as well as basic research. Teams at the NCI, in collaboration with researchers worldwide, identified the genes for BHD (Nickerson et al., 2002), Von-Hippel Lindau disease (Latif et al., 1993), and hereditary papillary renal cell cancer (Schmidt et al., 1997); work at the NCI on BHD has been ongoing since the 1990s. The NCI is in fact currently sponsoring a study investigating the genetics of BHD, “Genetic Analysis of Birt Hogg-Dube Syndrome and Characterization of Predisposition to Kidney Cancer”, which is recruiting participants.

As a genetic counsellor, Lindsay meets with individuals diagnosed with a hereditary condition. Genetic counsellors are often a very significant source of resources and support to families, offering guidance on understanding genetics, advice on managing a genetic condition, and time to discuss concerns, such as informing family members about a positive diagnosis. More information on genetic counselling and links for finding a local counsellor are available here.

With over 15 years’ experience in BHD and having met hundreds of patients, Lindsay’s specialist experience and knowledge is invaluable. As a member of the NCI team dedicated to undertaking translational research in kidney cancer disorders, Lindsay has travelled the United States to undertake clinical research into BHD and is an author on a number of papers. Lindsay Middelton’s research interests also include analysing nursing developments in cancer genetics as well as inherited kidney disorders.

The BHD community has also been fortunate to benefit from Lindsay’s expertise at the BHD Symposium, where she has been graciously leading the Patient and Family sessions (see summaries from the Third BHD Symposium and the Fourth BHD Symposium).

For a closer insight into Lindsay’s work, have a look at her Video Interview. There is also an audio-only version available, as well as a written transcript. The following publications also give an overview of Lindsay Middelton’s research:

• Middelton L, Dimond E, Calzone K, Davis J, & Jenkins J (2002). The role of the nurse in cancer genetics. Cancer nursing, 25 (3), 196-206 PMID: 12040228
• Singer EA, Bratslavsky G, Middelton L, Srinivasan R, & Linehan WM (2011). Impact of genetics on the diagnosis and treatment of renal cancer. Current urology reports, 12 (1), 47-55 PMID: 21128028
• Zbar B, Glenn G, Merino M, Middelton L, Peterson J, Toro J, Coleman J, Pinto P, Schmidt LS, Choyke P, & Linehan WM (2007). Familial renal carcinoma: clinical evaluation, clinical subtypes and risk of renal carcinoma development. The Journal of urology, 177 (2) PMID: 17222609

The authors used the Illumina Infinium HumanMethylation27 BeadChip array to directly assay the DNA methylation status of >14,000 genes in 38 samples of sporadic RCC and 9 normal kidney samples. Aberrant hyper- and hypo-methylation was observed in several (but not all) tumours when compared to control samples. Closer analysis identified a number of genes that were both highly methylated and had a functional relevance to cancer. In addition, this technique was verified using bisulphite sequencing and combined bisulfite restriction analysis (CoBRA).

Cluster analysis was used to group these genes into 5 categories depending on their level of methylation, and no association was observed between these groups and VHL mutation status. 6 genes (SLC34A2, OVOL1, DLEC1, TMPRSS2, SST and BMP4) were then investigated further and were shown to be methylated in a variety of RCC cell lines. These genes were also re-expressed in these cells after the addition of 5-Aza-2’-deoxycytidine, a DNA demethylating agent. Furthermore, the 6 genes exhibited both tumour-specific methylation and reduced expression when compared to normal kidney controls.

To investigate the functional impact of these genes, siRNA was used to knockdown OVOL1, SST and DLEC1 in HEK293 cells. Upon knockdown, anchorage-independent growth was significantly increased, especially with the OVOL1 knockdown. Moreover, real-time RT-PCR demonstrated that OVOL1 knockdown led to an increase in the expression of the proto-oncogene MYC (when compared to siRNA controls). OVOL1 is a zinc-finger transcription factor that is a downstream target of TGF-β signalling, and it has not been previously associated with human cancer.

In summary, this study has implicated a number of genes in the development of sporadic RCC, which could be used to develop novel biomarkers and (epigenetic) therapies. Khoo et al. (2003) noted that FLCN could also be inactivated by DNA methylation in sporadic RCC. Consequently, could DNA methylation play a role in BHD syndrome, for example, where no known FLCN mutations have been identified?

• Khoo SK, Kahnoski K, Sugimura J, Petillo D, Chen J, Shockley K, Ludlow J, Knapp R, Giraud S, Richard S, Nordenskjöld M, & Teh BT (2003). Inactivation of BHD in sporadic renal tumors. Cancer research, 63 (15), 4583-7 PMID: 12907635
• Morris MR, & Maher ER (2010). Epigenetics of renal cell carcinoma: the path towards new diagnostics and therapeutics. Genome medicine, 2 (9) PMID: 20815920
• Ricketts CJ, Morris MR, Gentle D, Brown M, Wake N, Woodward ER, Clarke N, Latif F, & Maher ER (2012). Genome-wide CpG island methylation analysis implicates novel genes in the pathogenesis of renal cell carcinoma. Epigenetics : official journal of the DNA Methylation Society, 7 (3), 278-90 PMID: 22430804

Tri-fold pamphlets (print on both sides of A4 and fold)

BHD syndrome: Diagnosis Information

BHD syndrome: Lung Symptoms and Treatment Options

BHD syndrome: Skin Symptoms and Treatment Options

BHD syndrome: Kidney Symptoms

BHD syndrome: Kidney Treatment Options

Sources for BHD syndrome information pamphlets

One-page clinical introduction pamphlet

BHD syndrome: Clinical Introduction

Publication date: February 2012
Review date: February 2014

To find out more, download the latest version of the database here.

Explore the diagram here.

The article is in Swedish; the abstract is also available in English.

To find out more, download the latest version of the database here.

Bradley et al is freely available to download in the BHD Article Library: Clinical section.

Following the welcoming reception on the 28th, the core patient and family activities took place on the 29th. After the clinical presentations, including an appraisal of screening guidelines for kidney tumours, (of which more details can be found in the previous Symposium live update post and Highlights post), a genetic counsellor from the NIH led a full afternoon of sharing experiences, reviewing research, and brainstorming new directions. We were also fortunate to welcome representatives from The LAM Foundation and the VHL Family Alliance to share strategies. LAM and VHL are conditions which have biological overlaps with BHD syndrome.

The Q&A portion of the patient sessions covered a number of concerns. For skin symptoms, the consensus is that there are a variety of treatments possible, but unfortunately these are not permanent and there are too few reports to evaluate which is the best temporary treatment. There is therefore need for studies into the best available treatment as well as investigations into experimental treatments. This year’s sessions also featured a greater emphasis on BHD lung symptoms, acting on observations from the Third BHD Symposium. Dr Frank McCormack, a pulmonologist from the University of Cincinnati responded to questions focusing on precautions, treatments and current understanding. Major points included the reiteration that BHD lung symptoms are not considered to be progressive and that air travel does not seem to pose a significant risk for pneumothorax, as investigated by Taveira-DaSilva et al., 2009. However, each person is different, so it may be helpful to speak with a doctor individually about air travel. Flu immunisations and smoking cessation were also recommended.

Additionally, following on from suggestions, BHDSyndrome.org will soon feature a private Forum for patients. There is also a private messaging system already in place, where any registered user can message someone who has posted to the Forum and opted into the system. If you have any suggestions or comments for BHDSyndrome.org, please complete the feedback form, which is always available on the For Families menu, the For Researchers menu and the Contact Us page.

All comments on the Symposium were greatly appreciated. We are excited to begin planning for the Fifth BHD Symposium and implementing ideas for improving the programme. Thank you for participating in the Fourth BHD Symposium!

• Taveira-DaSilva, A., Burstein, D., Hathaway, O., Fontana, J., Gochuico, B., Avila, N., & Moss, J. (2009). Pneumothorax After Air Travel in Lymphangioleiomyomatosis, Idiopathic Pulmonary Fibrosis, and Sarcoidosis Chest, 136 (3), 665-670 DOI: 10.1378/chest.08-3034