juvenile polyposis syndrome is an autosomal dominant inherited disorder characterized by multiple juvenile polyps arising in the gastrointestinal tract and an increased risk of gastrointestinal cancers specifically colon cancer bmpr1a and smad4 germline mutations have been found in patients with juvenile polyposis syndrome we identified a bmpr1a mutation which involves a duplication of coding exon 3 c 230 452 333 441dup1995 on multiple ligation dependent probe amplification in a patient with juvenile polyposis syndrome the mutation causes a frameshift producing a truncated protein p d112nfsx2 therefore the mutation is believed to be pathogenic we also identified a duplication breakpoint in which alu sequences are located these results suggest that the duplication event resulted from recombination between alu sequences to our knowledge partial duplication in the bmpr1a gene has not been reported previously this is the first case report to document coding exon 3 duplication in the bmpr1a gene in a patient with juvenile polyposis syndrome.