"MUTYH-Associated Polyposis" – What Is It?
MUTYH-associated polyposis (MAP) is a hereditary disease that significantly increases the risk of developing intestinal polyps and colorectal cancer. Both manifestations usually only occur in adulthood. There is also an increased risk of developing polyps and malignant tumors of the duodenum. Manifestations outside the gastrointestinal tract are also possible.
How Is "MUTYH-Associated Polyposis" Diagnosed?
Suspected Diagnosis
MUTYH-associated polyposis is suspected in the following clinical findings:
- Colon adenomas and/or colon polyps in a number of:
- 1-10 (at the age of <40 years)
- 10 (at the age of 40-60 years)
- >20 (at the age of >60 years)
- 20 to several hundred colon adenomas and/or colon polyps
- Polyposis coli (e.g.,>100 colon polyps) without APC germline mutation
- Colorectal cancer at the age of <40
- Family history of colorectal cancer (± polyps)
Genetic Diagnostics
The diagnosis of “MUTYH-associated polyposis” is confirmed by the detection of a mutation, i.e., a genetic change in the MUTYH gene. Both gene copies must be affected.
What Is the Risk of Cancer?
In MAP, polyps usually only appear in adulthood and are limited in number to between ten and several hundred. These polyps tend to degenerate, which can then lead to bowel cancer. However, it is also possible to develop bowel cancer without having developed polyps beforehand. Without early detection measures, the lifetime risk of developing bowel cancer is between 43% and 100%.
Almost a quarter of MAP patients also have polyps in the duodenum. Malignant tumors can also develop here. The lifetime risk of duodenal cancer is around 4%.
In addition, the following manifestations, some of them malignant, can occur outside the gastrointestinal tract:
- Ovarian, bladder, breast and uterine cancer
- Skin: benign and malignant tumors of the sebaceous glands, melanoma, squamous cell carcinoma, basal cell carcinoma, benign skin tumors
- Thyroid gland: thyroid cancer, nodular goiter, individual thyroid nodules
- Jaw cysts
What Is Known About the Development of "MUTYH-Associated Polyposis"?
MUTYH-associated polyposis is caused by a mutation, i.e., a genetic change in the MUTYH gene. This gene codes for the MUTYH protein, which repairs damage to the DNA that carries our genetic information. If the MUTYH gene is present in an altered form, the protein can no longer function correctly, so damage to the DNA cannot be repaired. This leads to the development of polyps and tumors.
As MUTYH-associated polyposis is a genetic disease, gene mutations are passed on from generation to generation. If two mutated genes meet in an individual, this person is homozygous for this mutation, and the disease develops. This form of inheritance is referred to as autosomal recessive inheritance.
Is There Any Form of Treatment Available?
Conspicuous colon polyps should be permanently removed. If removal of individual polyps (polypectomy) is not possible due to the large number or high density of polyps, removal of the affected section of the colon should be considered. Complete surgical removal of the colon (colectomy) is recommended as soon as adenomas (benign tumors that are considered precancerous) appear. Still, this procedure can be delayed depending on the size, histology, and number of adenomatous polyps. If a colon carcinoma is diagnosed, a colectomy is unavoidable.
Diagnosis of " MUTYH-Associated Polyposis" What's Next?
If you have been diagnosed with this cancer predisposition syndrome, it is important to see a specialist. The following section explains whether cancer screening tests or other measures are needed and how they should be carried out. We also give you some valuable tips on what you can do yourself. If you have any questions, please do not hesitate to contact us or your doctor.
Diagnosis of " MUTYH-Associated Polyposis" What's Next?
If you have been diagnosed with this cancer predisposition syndrome, it is important to see a specialist. The following section explains whether cancer screening tests or other measures are needed and how they should be carried out. We also give you some valuable tips on what you can do yourself. If you have any questions, please do not hesitate to contact us or your doctor.
Medical Measures for Early Detection
No early detection measures are recommended for children and adolescents.
The following recommendations apply to adults:
- Colonoscopy every 2 years from the age of 18
- Gastroscopy from 25-30 years
If a person with a MUTYH mutation wishes to have children, genetic testing of the partner can be considered before conception. This is advisable because MUTYH-associated polyposis only develops if both parents pass on a mutated gene to the child (autosomal recessive inheritance).
MUTYH-Associated Polyposis – What You Can Do Yourself
You Should Pay Attention to This
People with this tendency to colorectal cancer should be treated at a center that offers early detection.
Regardless of the screening tests, you should always consult a doctor as soon as you experience gastrointestinal tract symptoms. These can be blood or mucus discharge from the bowel, stool abnormalities such as diarrhea or constipation, flatulence, or pain. However, non-specific signs such as weight loss should also be noticed and reported to a doctor so that colon cancer can be investigated.
You should also urgently consult a doctor if you have any other new abnormalities or complaints, such as difficulty swallowing, skin lesions, or abdominal pain.
Further Information
Patients can also register for the CPS registry at any time or have this done by the doctors in charge.
Any further questions?
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