The VHL gene test is requested along with other tests when a doctor suspects that someone has Von Hippel-Lindau syndrome. It may also be ordered to predict if a family member has an inherited mutation or variant in the VHL gene. VHL is the only gene known to be the cause of Von Hippel-Lindau syndrome.
What is being tested?
The VHL gene provides instructions for making a protein that functions as part of a complex (a group of proteins that work together) called the VCB-CUL2 complex. This complex targets other proteins to be broken down (degraded) by the cell when they are no longer needed. One of the targets of the VCB-CUL2 complex is a protein called hypoxia-inducible factor 2-alpha. HIF controls several genes involved in cell division, the formation of new blood vessels, and the production of red blood cells.
The VHL protein likely plays a role in the regulation of other genes and control of cell division. Based on this function, the VHL protein is classified as a tumour suppressor, which means it prevents cells from growing and dividing too rapidly or in an uncontrolled way.
More than 370 inherited mutations (faults) in the VHL gene have been identified in people with Von Hippel-Lindau syndrome. In this condition, the mutations either prevent the production of any VHL protein or lead to the production of an abnormal version of the protein.
How is it used?
The test is used, along with specific clinical criteria (symptoms and signs) and other tests, to establish a clinical diagnosis of Von Hippel-Lindau syndrome.
Von Hippel-Lindau syndrome is a rare inherited disorder which can affect many organs in the body. The features of the disease include an abnormal growth of blood vessels in certain parts of the body. These may knot together to form benign growths known as angiomas. They may develop in the eyes, brain, spinal cord, the adrenal glands and other parts of the body. People with Von Hippel-Lindau disease are also predisposed to developing cancers of the kidney (renal cell carcinomas). Features of the condition may vary greatly between affected individuals, and even between those from the same family. The age of onset of symptoms may also vary, although tumours usually first appear in young adulthood.
Angiomas that develop in the brain and spinal cord (haemangioblastomas) can cause headaches, vomiting, weakness, and a loss of muscle coordination. Retinal angiomas (affecting the light-sensitive tissue that lines the back of the eye) may cause vision loss. Tumours that develop in the adrenal glands (pheochromocytomas) often cause no symptoms, but in some cases can produce an excess of hormones that cause dangerously high blood pressure. Renal cell carcinoma is the leading cause of death in people with Von Hippel-Lindau syndrome.
When is it requested?
The VHL gene test may be requested, along with other tests, when a clinician suspects that a person has Von Hippel-Lindau syndrome. It may also be ordered to predict if a family member has an inherited mutation in the VHL gene, and is predisposed to developing Von Hippel-Lindau syndrome.
What does the result mean?
Having a VHL gene mutation increases your risk of developing tumours in certain parts of the body including the eyes, ears, brain, spinal cord, adrenal glands, and kidneys. Not everyone with Von Hippel-Lindau disease will develop cancer over their lifetime.
Relatives of those with Von Hippel-Lindau syndrome can also be tested for the same mutation to determine whether they would benefit from regular screening. If a relative is found not to have inherited the mutation then no further screening is necessary.
Is there anything else I should know?
VHL is the only gene known to be associated with von Hippel-Lindau syndrome. The current laboratory techniques that are used can detect over 80% of VHL mutations. Once a mutation has been identified in one affected family member, genetic testing for VHL for other family members is 100% accurate. It is important to have genetic counselling before undergoing genetic testing.
Common questions
Von Hippel Lindau syndrome is a disease that results from an error, or a mutation, in a gene called the VHL gene. Genes come in pairs and a child inherits one gene from each parent. The mutation may be transmitted from a parent to a child following a dominant pattern of inheritance. This means that if one parent has a mutation of the VHL gene their child has a 50% chance of inheriting that mutation. In about 20% of cases, the mutation occurs for the first time in a person with no family history of the condition. If a person is the first family member affected by VHL, the siblings and parents are at low risk of having VHL, but that person’s child has a 50% chance of inheriting the VHL gene mutation.
Family members (including children) of someone with a faulty VHL gene can have genetic testing to check who has the faulty gene and who does not.
If a person does have the faulty VHL gene, they can pass it onto their children. Each child has a 50% (1 in 2) chance of being born with it. Pregnancy planning options are available to people who want to prevent the faulty gene from being passed on. Family members at risk of developing von Hippel-Lindau syndrome are offered surveillance and, as required, early intervention to reduce the risk or severity of this disorder.
If a person does not have the faulty VHL gene, they have the same chance of developing cancer as the general population (unless there are other factors that increase this risk).
The testing is covered by Medicare when a specialist doctor suspects that a person has Von-Hippel Lindau syndrome.
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