Phenotypic diversity among juvenile polyposis syndrome patients from different ethnic background

Juvenile polyposis syndrome (JPS), has diverse phenotypes. Aim: To assess mutation rate, clinical features and genotype-phenotype correlation among Israeli JPS kindreds from different ethnicities. Methods Patients' data were extracted retrospectively from 5 centers. Results Thirty five kindreds (49 patients) were included. Thirty one (89%) Jewish [10 (32%) Ashkenazi; 9 (29%) Sephardi; 11 (35%) non-Russia former Soviet-Union countries (NRFSU), one (3%) unknown]. 40/49 individuals from 27 families underwent genetic testing. Among them 34, from 21 families (85, 78%, respectively) had a pathogenic mutation: BMPR1A n = 15 (71%), SMAD4 n = 6 families (29%). While no SMAD4 mutation was described among Jewish families from NRFSU, 7 NRFSU families carried a founder mutation comprising a large genomic deletion of BMPR1A. GI involvement was reported in 42 patients (86%): colonic polyps (n = 40, 95%, > 50 polyps n = 14, 35%) and 12 underwent colonic resection. Fourteen patients (34%) had gastric or small bowel involvement (n = 5) and 4\14 underwent gastrectomy due to polyp burden. Families from NRFSU had more gastric involvement (66.7% vs. 22.2%- Sephardic and 20%- Ashkenazi Jews; p = 0.038), with more gastric polyps (p = 0.017). Conclusions We demonstrated a high rate of mutation detection in the heterogeneous population of Israel. Patients from NRFSU with BMPR1A mutation had high rate of gastric involvement.