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Juvenile polyposis of infancy
Juvenile polyposis of infancy (JPI) is the most severe form of juvenile gastrointestinal polyposis (see this term) and is characterized by pancolonic hamartomatous polyposis from stomach to rectum, diagnosed in the first two years of life.
ORPHA:79076Classification level: Subtype of disorder
Prevalence is unknown but only 11 cases have been described in the literature so far.
The digestive phenotype is severe and life-threatening, with gastrointestinal bleeding, diarrhea, inanition and exudative enteropathy. Early death has been reported and the risk of cancer in surviving children has not yet been clearly established. Signs of the Cowden or Bannayan-Riley-Ruvalcaba (BRRS) syndromes (see these terms) such as macrocephaly, lipomas, and hemangioblastomas can be observed. Dysmorphic signs, such as a large forehead, hypertelorism, down-slanting palpebral fissures, a flat nasal bridge, low-set ears, and a small mouth and chin, have also been described. Mild intellectual deficit has been reported in some cases. Recently, a less severe form of JPI has been described in several patients with early-onset gastrointestinal tract juvenile polyps but with a mild digestive phenotype.
The majority of cases are caused by a large deletion in the chromosome 10q23 region, encompassing the PTEN and BMPR1A genes. The hypothesis is that the severe digestive phenotype results from a cooperative effect of the deletion of each gene. However, this hypothesis is under debate as the patients with the mild digestive phenotype were also found to harbor a deletion of the PTEN and BMPR1A genes.
Diagnosis may be suspected on the basis of the clinical picture and digestive endoscopy investigation but is confirmed by detection of the 10q23 deletion. This deletion is rarely detected through karyotype analysis, and FISH or Array-CGH, followed by semiquantitative PCR methods (QMPSF, MLPA, MP/LC), are required to define the length and the location of the deletions.
The differential diagnosis should include the allelic disorders Cowden syndrome and Bannayan-Riley-Ruvalcaba syndrome, which are caused by mutations in the PTEN gene, as well as familial adenomatous polyposis and Peutz-Jeghers syndrome (see these terms).
JPI appears to be sporadic.
Management and treatment
Management revolves around colonoscopy with endoscopic polypectomy. Early endoscopic polypectomy may reduce morbidity by reducing the risk of the cancer, bleeding, or intestinal obstruction.
However, as JPI is life-threatening and colectomy is generally necessary in infancy, the prognosis during infancy is severe and the survival rate is generally low. The prognosis for surviving children depends on the risk of gastrointestinal tract cancer.