Familial juvenile polyposisD12.6

Very rare, autosomal-dominantly inherited clinical picture characterized by multiple "juvenile polyps". The polyps are found particularly in the large intestine, stomach and small intestine. Juvenile polyps belong to the group of hamartomatous polyps, they often have inflammatory changes and are eroded on the surface.

30% of the cases occur in families.

Point mutations and large deletions in the SMAD4 gene (MADH4, DPC4 gene) are found in 30% of patients and in the BMPR1A gene in 20-25%. There are clear genotype-phenotype correlations: patients with a SMAD4 germline mutation have an increased risk of developing gastric polyps and gastric cancer as well as hereditary haemorrhagic telangiectasia (Osler-Rendu-Weber disease).

The search for a mutation in a family should always be carried out in a person who is already surely ill. Once the mutation has been identified, other risk persons in the family can be (predictively) tested for this mutation.

In the case of more severe polyp infestation, chronic bleeding of the gastrointestinal tract with consecutive development of anemia and hypoproteinemia. This can result in developmental delays in childhood. Clinical symptoms of hereditary haemorrhagic telangiectasia (Morbus Rendu-Osler-Weber) occur almost exclusively in carriers of a SMAD4 mutation.

Juvenile polyps are benign per se. However, carriers of this genetic defect have a high risk of developing colon cancer up to the age of 60. In addition, there is an increased risk of stomach, small intestine and pancreatic cancer.

Regular endoscopic check-ups.

Familial juvenile polyposis belongs to the "Hamartösen Polyposis Syndromes".