BMPR1A and juvenile polyposis syndrome: To better understand the association between genotype and phenotype, we further summarized latest evidence to delineate features of BMPR1A-related disorders, and compared the difference between mutation carriers of SMAD4 and BMPR1A. Table 2 summarizes the extended phenotypic spectrum beyond JPS attributed to pathogenic or likely pathogenic variants of BMPR1A. BMPR1A encodes a crucial subunit of serine/threonine kinase receptor complex in the TGF-β pathway, which was reported as the second causative gene of JPS by Howe et al[13] in 2001.