PT  - JOURNAL ARTICLE
AU  - S Aretz
AU  - D Stienen
AU  - S Uhlhaas
AU  - M Stolte
AU  - M M Entius
AU  - S Loff
AU  - W Back
AU  - A Kaufmann
AU  - K-M Keller
AU  - S H Blaas
AU  - R Siebert
AU  - S Vogt
AU  - S Spranger
AU  - E Holinski-Feder
AU  - L Sunde
AU  - P Propping
AU  - W Friedl
TI  - High proportion of large genomic deletions and a genotype–phenotype update in 80 unrelated families with juvenile polyposis syndrome
AID  - 10.1136/jmg.2007.052506
DP  - 2007 Nov 01
TA  - Journal of Medical Genetics
PG  - 702--709
VI  - 44
IP  - 11
4099  - http://jmg.bmj.com/content/44/11/702.short
4100  - http://jmg.bmj.com/content/44/11/702.full
SO  - J Med Genet2007 Nov 01; 44
AB  - Background: In patients with juvenile polyposis syndrome (JPS) the frequency of large genomic deletions in the SMAD4 and BMPR1A genes was unknown.Methods: Mutation and phenotype analysis was used in 80 unrelated patients of whom 65 met the clinical criteria for JPS (typical JPS) and 15 were suspected to have JPS.Results: By direct sequencing of the two genes, point mutations were identified in 30 patients (46% of typical JPS). Using MLPA, large genomic deletions were found in 14% of all patients with typical JPS (six deletions in SMAD4 and three deletions in BMPR1A). Mutation analysis of the PTEN gene in the remaining 41 mutation negative cases uncovered a point mutation in two patients (5%). SMAD4 mutation carriers had a significantly higher frequency of gastric polyposis (73%) than did patients with BMPR1A mutations (8%) (p<0.001); all seven cases of gastric cancer occurred in families with SMAD4 mutations. SMAD4 mutation carriers with gastric polyps were significantly older at gastroscopy than those without (p<0.001). In 22% of the 23 unrelated SMAD4 mutation carriers, hereditary hemorrhagic telangiectasia (HHT) was also diagnosed clinically. The documented histologic findings encompassed a wide distribution of different polyp types, comparable with that described in hereditary mixed polyposis syndromes (HMPS).Conclusions: Screening for large deletions raised the mutation detection rate to 60% in the 65 patients with typical JPS. A strong genotype-phenotype correlation for gastric polyposis, gastric cancer, and HHT was identified, which should have implications for counselling and surveillance. Histopathological results in hamartomatous polyposis syndromes must be critically interpreted.