MUTYH-associated polyposis is closely related to adenomatous familial polyposis and is caused by a genetic mutation. Patients suffer from multiple colon polyps with degeneration risk. Regular colonoscopy is mandatory.

What is a MUTYH-associated polyposis?

Polyposis is polyposis in hollow organs. Polyps are protuberances of the mucous membrane, which occur more frequently in the gastrointestinal tract and are referred to in this case as gastrointestinal polyposis. Especially in the context of polyposis gastrointestinalis exist different diseases with genetic and hereditary basis.

One of them is the autosomal dominant hereditary MUTYH-associated polyposis, also known as MAP or MHY associated polyposi. The disease was discovered in 2002 as an independent hereditary disease. It behaves as a clinically attenuated variant of familial adenomatous polyposis (FAP).

For this reason, researchers have since discovered that the generalized course of the disease is similar to AFAP. In addition, patients with a mild history of adenomatous familial polyposis are now diagnosed with MAP in up to 20 percent of all cases. Thus, the MUTYH-associated polyposis can be considered in the broadest sense as the most favorable sub-variant or close relative of the adenomatous familial polyposis. Studies show that about one percent of the population is the carrier of the disease.

causes

The cause of the MUTYH-associated polyposis lies in the genes. More specifically, it is a mutation in the MUTYH gene, which is located on chromosome 1 in the gene locus 1p34.3-p32.1. The associated base pairs 45, 464, 007 to 45, 475, 152 carry 16 encoded exons. The parent MUTYH gene is involved in the production of a DNA-repairing protein in a healthy organism.

It is the so-called MUTYH glycosylase, which monitors the base pair formation. The base pairs of the gene occur physiologically in two different forms and thus consist of adenine with thymine or guanine with cytosine. Upon oxidation, the base pair partners shift. For example, guanine can pair with adenine.

In healthy organisms, the DNA-repairing protein recognizes this event and repairs the defect. In a mutation in the MUTYH gene, the MUTYH glycosylase loses its actual form and can no longer sufficiently fulfill its tasks. The inheritance of MUTYH-associated polyposis is autosomal recessive. Siblings of a patient thus have a 25 percent risk of inheriting the polyp disease. Children of a patient definitely carry the hereditary disease.

Symptoms, complaints & signs

Patients of MUTYH-associated polyposis suffer from polyps of the colon. The polyps can occur in groups of up to 100 pieces. In some cases, only ten polyps were reported. With polyps of the large intestine accompanying symptoms such as bleeding, flatulence, colic and pain in the rectum area are associated.

In addition, constipation, diarrhea and severe weight loss often occur. Despite the sometimes considerable number of large intestine polyps, the disease is considered to be milder in its course than the familial adenomatous polyposis coli. Regardless, hyperplastic or serrated adenomas are often found among multiple polyps.

Thus, the hereditary disease is associated with an increased risk of cancer. The mean age for colon carcinoma is about 50 years for carriers of the disease. The carcinomas are formed preferentially in the proximal portion of the intestine. Also benign bone tumors in the sense of osteomas were increasingly observed in the context of MUTYH-associated polyposis.

Diagnosis & disease course

The diagnosis of a MUTYH-associated polyposis is in most cases only made at a higher age than 50 years of life. In most cases, those affected seek medical attention for bleeding or persistent pain in the rectum. As part of the diagnosis, an endoscopy including biopsy of the polyps is usually performed.

A human genetic examination can round off the diagnosis. This method is especially indicated for cases in which despite many colonic polyps a FAP was excluded. In the human genetic analysis, a complete sequencing of the MUTYH gene is performed. Although patients with MUTYH-associated polyposis are at increased risk of colorectal cancer, their prognosis is far more favorable compared to patients with FAP.

complications

Through this disease sufferers primarily suffer from complaints in the intestine. This leads to the formation of so-called polyps, which eventually lead to colic, flatulence and pain in the intestine and stomach. Not infrequently, sufferers also suffer from diarrhea or constipation and thus a greatly reduced quality of life. Furthermore, permanent discomfort in the stomach and intestine can lead to mental problems or depression.

Also, the risk of cancer is significantly increased by this disease, so that patients are dependent on various preventive care. Not sailing, the patients eat less food through this disease, so it comes to deficiency symptoms or underweight. Especially the risk for colorectal cancer increases enormously due to this disease.

The treatment is usually done with the help of medication. There are no special complications. Through various regular examinations and controls further diseases can be avoided or detected early. If the sufferer suffers from an underweight or a deficiency, then the missing nutrients must be administered by an infusion.

When should you go to the doctor?

Irregularities in the intestine should be observed by the person concerned. If they persist or increase over several days, they should be clarified by a doctor. In case of bloating, constipation or diarrhea, a visit to the doctor is recommended. If it comes to intestinal sounds, a feeling of pressure or pain in the abdomen, there is a disorder that needs medical attention, so that no further complications follow.

A loss of appetite, an unwanted decrease in body weight and a feeling of internal drought are signs that require action. A decrease in existing strength, sleep disturbances or general malaise should be investigated and treated. If everyday professional and private obligations can no longer be met, the person concerned should seek the help of a doctor.

If bleeding occurs during bowel movements, itching occurs or open wounds on the anus, a visit to a doctor is advisable. Pathogens can invade the organism and lead to other diseases. In addition, a sterile wound care is necessary to prevent blood poisoning. A doctor should be consulted if skin changes, a burning sensation in the anus, fever, malaise or internal weakness occur.

Treatment & Therapy

A causal therapy is not available for patients with MAP because the disease is genetic and is due to DNA damage. Substantial progress has been made in gene therapy so that a therapeutic approach based on gene therapy can not be ruled out within the next few decades.

However, as gene therapy approaches are not yet in the clinical phase, patients with MUTYH-associated polyposis are so far treated exclusively symptomatically. The focus of symptomatic treatment is less on actual therapy than regular control. Check-ups at close intervals are mandatory due to the increased risk of cancer and should take place at the latest from the age of 30.

Biopsies are taken from hyperplastic or otherwise conspicuous polyps as part of the check-ups. If necessary, particularly noticeable representatives are removed by resection in order to reduce the danger of degeneration. In addition to the check-ups, patients with the disease have a symptomatic pain therapy available, which usually corresponds to a drug treatment.

If malnutrition occurs due to persistent diarrhea, the respective deficiency is compensated with intravenous infusions.

Outlook & Forecast

MUTYH-associated polyposis (MAP) obviously increases the risk of developing colorectal cancer due to genetic factors. Therefore, the prognosis is not so positive in the long term. Therefore, it is important first of all to have an accurate and comprehensive diagnosis to be able to clearly differentiate the MUTYH-associated polyposis as such from similar hereditary gastrointestinal polyposis syndromes. Second, adequate therapy and long-term monitoring of colonic polyps through regular examinations of the intestinal tract is useful.

The degeneration risk of this type of intestinal polyp is significantly higher than other intestinal diseases. For this reason, MUTYH-associated polyposis requires regular colonoscopies. As a result, any colorectal cancer can be detected as early as possible. Compared with the so-called FAP polyposis, the prognosis is significantly better for people with a confirmed MUTYH-associated polyposis. But the prospects are still bad overall.

In this respect, it can be said that a MUTYH-associated polyposis can indeed involve long-term colorectal cancer risks. However, these risks can be minimized by regular colonoscopy and a genetic diagnosis of the polyp type. In this case, early detection is a safe tool for curing a colorectal cancer diagnosis.

It is also important that patients with MUTYH-associated polyposis pay attention to their nutritional value. With constant intestinal complaints easily questionable nutrient deficits arise. If necessary, infusion treatments are necessary to ensure nutrient supply.

prevention

Molecular genetic analyzes are a preventive step in the context of MAP. Above all, people with a corresponding family history learn about the analyzes of whether they are homozygous carriers of the MUTYH gene mutation. If this is the case, regular colonoscopies from the age of 30 serve to prevent cancer.

aftercare

Due to the disease sufferers suffer from severe complications and serious complaints. Therefore, this disease must be consulted at the first symptoms and signs a doctor, so it does not lead to a further deterioration of the symptoms. If the disease is not treated, in the worst case it can lead to the death of the person affected.

The affected suffer primarily from severe abdominal discomfort. It causes diarrhea, constipation and generally severe abdominal pain. Many patients also suffer from flatulence and even bloody diarrhea. Due to the permanent abdominal discomfort, it can also lead to a heavy loss of weight. The risk of cancer also increases due to the symptoms, so many patients get colon cancer.

The symptoms themselves can lead to depression or other severe mental disorders in some sufferers, so they also depend on psychological treatment. The further course depends strongly on the exact form of the complaints. It may also reduce the life expectancy of the person affected due to the disease.

You can do that yourself

Patients with MUTYH-associated polyposis suffer from unpleasant symptoms that reduce quality of life due to the disease of the large intestine. In their own interest, those concerned regularly seek out various specialists and undergo the offered preventive medical check-ups in order to be able to diagnose any possible cancer in good time. Due to the uncertainty about the course of the disease and the symptoms themselves, some patients develop anxiety disorders or even depression. Then it is urgent to consult a psychologist. The psychotherapist supports the patient in dealing with the physical illness and strengthens the mental stability.

If the doctor prescribes medication, the person affected has to take it exactly according to the doctor's instructions. Patients often suffer from colic, diarrhea or constipation, which also adversely affect their daily lives and make participation in society difficult. Therefore, it is urgent to consult a medical nutritionist. This develops an individual diet plan for the patient in order to reduce the discomfort and to ensure the often impaired supply of nutrients.

It is also helpful if those concerned refrain from smoking and consuming alcoholic beverages. This saves the organism the processing of the corresponding toxins and at best has a beneficial effect on the course of the disease.

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