Birt-Hogg-Dubé syndrome and kidney cancer — what it means for your kidneys

Birt-Hogg-Dubé syndrome, often shortened to BHD, is an inherited condition caused by a change in a single gene called FLCN. That gene makes a protein, folliculin, which helps keep cell growth in check. When one working copy is missing from birth, three parts of the body are affected more often than expected: the skin, the lungs and the kidneys. It is passed from parent to child, and each child of an affected parent either inherits the gene change or does not. Men and women are affected equally. The features usually appear in adult life rather than childhood, and not everyone in a family shows all three.

No. This is the single most important thing to understand about BHD. Carrying the FLCN gene change raises the lifetime chance of a kidney tumour above the general population, but many people who carry it never develop one, and plenty of those who do are found early through planned monitoring rather than through symptoms. The gene change is a reason to be watched properly, not a diagnosis of cancer. That is also why the diagnosis is worth having: once BHD is confirmed, the kidneys stop being a matter of chance and become something a team looks at on a schedule.

BHD kidney tumours differ from ordinary sporadic kidney cancer in a few ways that shape how they are managed. They are often multiple rather than single, they can appear in both kidneys, and they tend to be found at a younger age. The tumour types seen most often in BHD belong to the chromophobe, oncocytoma and hybrid oncocytic group, which as a rule grow slowly and behave less aggressively than other kidney cancers, although clear cell and papillary tumours also occur. Because more than one tumour may appear over a lifetime, preserving working kidney tissue is a priority in every treatment decision.

The skin sign is a scatter of small, painless, dome-shaped bumps called fibrofolliculomas, usually around the nose, cheeks, ears, neck and upper chest, appearing from adult life onwards. They are benign and are not skin cancer, but they are often the clue that leads to the diagnosis. In the lungs, BHD causes thin-walled cysts, typically towards the base of the lungs. These cysts are not cancer and usually do not cause breathlessness, but one can burst and cause a collapsed lung, which may happen more than once and often earlier in life than a collapsed lung normally would.

It usually starts with a pattern rather than a test: the characteristic skin bumps, a collapsed lung at a young age or lung cysts on a scan, kidney tumours in both kidneys or more than one, or a close relative already diagnosed. Where that pattern is present, the next step is genetic counselling, which is led in-house by medical oncology at CION, followed by a blood test that looks at the FLCN gene. NCCN guidance supports genetic risk evaluation for people with kidney cancer diagnosed young, with multiple or bilateral tumours, or with a suggestive family history. Counselling comes first because the result affects your relatives as well as you.

Once the gene change is identified in one person, testing relatives becomes far simpler, because the laboratory knows exactly what it is looking for. First-degree relatives are usually offered counselling and testing in adult life. Those who carry it move on to planned kidney monitoring; those who do not are released from it, and their own children are not at risk from this condition. That second outcome is common and is a genuinely useful result. Start with a consultation to map out who in the family should be approached and in what order, rather than testing everybody at once.