The most common extra-JPS phenotype was hereditary mixed polyposis syndrome (HMPS), which probably resulted from large genomic deletion, small deletion, or nonsense variants of BMPR1A. [14–16] It was reported that germline disease-causing variants of BMPR1A were detected in 4/8 (50%) of the HMPS families. This evidence concerns the gene BMPR1A and hereditary mixed polyposis syndrome.