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BAP1 Tumour Predisposition Syndrome

BAP1 tumour predisposition syndrome (BAP1-TPDS) is a rare genetic disorder that causes an increased risk of developing various benign (non-cancerous) and malignant (cancerous) tumours in affected individuals. It is caused by a mutation in the BRCA-1 associated protein (BAP1) gene, which acts as a tumour suppressor in the body.

Familial cancer syndromes, also known as hereditary cancer syndromes, are rare conditions that cause an increased risk of cancer as the result of inherited genetic mutations in certain cancer-related genes. They can affect both adults and children, however they generally develop in people at a younger age than normal. While familial cancer syndromes are not classified as cancer, they are equally as severe and can be life-threatening as they are associated with the development of various tumours throughout the body. Having a familial cancer syndrome does not guarantee the development of cancer, however the risk of developing cancer is higher than those who do not have a familial cancer syndrome.

BAP1-TPDS tends to affect the sexes equally, and has a varying age of diagnosis.

BAP1-TPDS is most commonly associated with the development of skin tumours, however it has also been linked to other types of tumours. Some examples include:

  • Benign skin tumours, most commonly BAP1-inactivated melanocytic tumours (BIMT).

The following tumours may also have an increased incidence in people with BAP1-TPDS, however more research is needed to confirm:

Treatment

When cancers are detected, they are staged and graded based on size, metastasis, and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you. However, each patient with BAP1-TPDS will present with a unique disease behaviour, with varying tumour locations and symptoms. As such, there is no one treatment method that will work for everyone, and there is no standard staging system for this disease. Instead of staging and grading, your doctor will recommend a treatment plan based on the following factors:

  • Type of tumours present.
  • Whether the tumours are malignant (cancerous) or benign (non-cancerous).
  • Tumour location.
  • Whether or not malignant tumours have metastasised.
  • Your age.
  • General health.
  • Your treatment preferences.

Your doctor may also recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.

Treatment options for tumours associated with BAP1-TPDS may include:

  • Surgery to remove as much of the tumour(s) as possible – these will vary based on tumour type and location.
  • Chemotherapy.
  • Radiation therapy.
  • Targeted therapy, potentially including PARP inhibitors.
  • Clinical trials.
  • Palliative care.

Cancer Screening

Once a diagnosis of BAP1-TPDS has been confirmed, implementing a targeted screening plan becomes essential due to the increased risk of developing certain cancers.  The content of this plan will vary from person to person based on the genetic mutation involved, your family’s history of cancer and the types of cancers that may be present. It will also outline the routine tests you should have and how regularly you should have them.  Some recommendations for BAP1-TPDS may include:

  • Annual physical examination.
  • Skin examination every 6-12 months starting at 18 years old.
  • Annual eye examination starting at 11-16 years old, then every six months after 30.
  • Annual abdominal imaging alternating between MRI and ultrasound beginning at age 30.

Screening options for BAP1-TPDS may evolve as new technologies are developed and our understanding of the condition grows. It is essential to discuss your individual circumstances with your healthcare team to determine the most appropriate screening plan for you.

Risk factors

BAP1-TPDS is caused by a mutation in the BRCA-1 associated protein (BAP1) gene, which acts as a tumour suppressor in the body. It is an autosomal dominant disease, which means you have a 50% chance of inheriting the disease if one of your parents carries the mutation.

Symptoms

The symptoms of BAP1-TPDS often vary by the type(s) of tumours present. General symptoms of BAP1-TPDS may include:

  • Between 5-50 skin macules/papules/nodules with some or all of the following characteristics:
    • Pink, orange or tan in colour.
    • Dome shaped.
    • Pedunculated (containing a stalk or stem).
    • Between 2-10mm in size.
  • Vision changes, potentially including:
    • Poor and/or blurred vision in one eye.
    • Loss or peripheral vision.
    • Seeing ‘wavy’ lines in your vision.
    • Vision flashes.
  • Fatigue.
  • Unexplained weight loss/loss of appetite.
  • Fevers.
  • Dyspnea.
  • Excessive sweating.
  • Haematuria.

Symptoms related to specific tumours can be found on our knowledgebase.

Not everyone with the symptoms above will have cancer, but see your general practitioner (GP) if you are concerned.

Diagnosis

If your doctor suspects you have tumours associated with BAP1-TPDS, they may order some of the following tests to confirm the diagnosis and refer you to a specialist for treatment. The tests required for diagnosis will often vary based on the symptoms present, and where the tumour(s) are suspected to be located.

  • Physical examination.
  • Genetic testing.
  • Eye tests.
  • Blood tests.
  • Urine tests.
  • Pulmonary function test.
  • Imaging tests, potentially including:
    • MRI (magnetic resonance imaging).
    • CT (computed tomography) scan.
    • Ultrasound.
    • Chest x-ray.
  • Exploratory procedures, such as an endoscopy.
  • Biopsy.

References

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