BMPR1A-associated juvenile polyposis
What Does It Mean to Test Positive for a BMPR1A Mutation?
Mutations in BMPR1A are associated with a condition known as BMPR1A-associated juvenile polyposis, which results in the development of benign tumors, or polyps, within the lining of the digestive tract. The name of the condition “juvenile” refers to the type of polyps identified, not the age of the affected individual.
What Are the Cancer Risks Associated with a BMPR1A Mutation?
BMPR1A mutations are primarily associated with an increased risk for colon cancer. Other cancers involving the upper digestive system (esophagus), stomach, small intestine, and pancreas have also been associated with this condition. The lifetime risk for colon cancer is reported to range from 40 to 50%, and the risk for gastric (stomach) cancer is 21%. Additional cancer risks of the digestive system are increased, but a specific risk percentage is not known.
|Cancer Type||Cancer Risk||Average Age of Onset||General Population Risk|
|Colon||40 to 50%||44 years||4.3%|
|Stomach||21%||50 to 55 years||< 1%|
|Other Gastrointestinal Tract||Increased||Unknown||1 to 2%|
Colon polyps (benign growths) can develop as early as infancy and throughout adulthood, with most affected individuals having polyps by age 20. These benign polyps have the potential to develop into cancer if not removed and can develop in other areas of the digestive system.
What Cancer Screening or Risk-Reducing Options Are Available?
The most important aspect of management of any individual with a BMPR1A mutation is increased cancer screening, to allow the earliest possible detection of any tumors. Screening guidelines have been determined for individuals identified to have a mutation in BMPR1A. Specifics of screening may vary depending on the individual's family and personal history.
For Men and Women
- Annual physical examinations are recommended.
- Colonoscopy is recommended beginning at age 15, or earlier for appropriate families. Colonoscopy should be repeated every two to three years, or more frequently when polyps are identified.
- Upper endoscopy is recommended beginning at age 15, or earlier for appropriate families. The frequency of follow-up endoscopy is generally every two to three years, or more frequently when polyps are identified.
- Surgical removal of the colon at an appropriate time, determined by an individual's colonoscopy findings, is known to dramatically reduce, if not prevent, the development of colon cancer.
What Is the Chance That Family Members of BMPR1A Mutation Carriers Have the Same Mutation?
BMPR1A mutations are passed down in a family. This means that family members of BMPR1A mutation carriers may have the same mutation and may also be at increased risk of developing cancer. However, up to 67% of the time, a sporadic genetic mutation occurs in a single family member, which means that an individual could be the first person in a family to have a BMPR1A mutation. In either case, it is important for BMPR1A mutation carriers to discuss genetic test results with family members.
- Close blood relatives of BMPR1A mutation carriers, such as parents, siblings, and children, have up to a 50% chance of having the same mutation.
- For individuals who are determined to be the first affected member of a family, testing is still indicated for biological children who have a 50% chance to inherit the BMPR1A mutation.
- More distant relatives, such as aunts, uncles, grandparents, and cousins, also have a chance of having the same BMPR1A mutation.
- A physician or a genetic counselor can help mutation carriers determine whether the mutation was more likely to have been inherited from the maternal or paternal side of the family. In general, the mutation will only be found on one side of the family, and it is more likely to be on the side of the family that has a history of colon cancer.
Genetic testing of family members can help determine which family members are at increased risk for cancer and may benefit from screening and/or risk-reduction options discussed above. Family members who test negative for a known familial BMPR1A mutation likely have the same risk for cancer as the general population and can follow the general population's screening guidelines.
What Else Should BMPR1A Mutation Carriers Know?
Mutation carriers who are interested in options to prevent passing their mutation to future children may wish to consider preimplantation genetic diagnosis (PGD). PGD is a procedure that involves in vitro fertilization (IVF) and can determine if an embryo carries the genetic mutation present in a family. Determining which embryos carry the family mutation may allow a mutation carrier to prevent the condition from being passed to future children. The decision to undergo PGD is personal. Mutation carriers and their family members can talk with a healthcare provider to learn more about their reproductive options.