SMAD4 and juvenile polyposis syndrome: HPSs include Peutz–Jeghers syndrome (PJS), which is caused by germline alterations in the STK11 gene, hereditary juvenile polyposis (JPS), which is caused by germline alterations in the BMPR1A and SMAD4 genes, and PTEN hamartoma tumor syndrome (PHTS), which is caused by germline alterations in the PTEN gene [10].