GREM1 and polyposis: In addition to the founder Ashkenazi duplication, additional (non-Ashkenazi) variants identified include: a 16-Kb duplication affecting the GREM1 5′ regulatory region identified in a large family affected with polyposis of multiple polyp types, CRC, breast and gastric cancer [97]; a 24-Kb tandem duplication in the 5′ regulatory region identified in an Amsterdam-positive nonpolyposis CRC family, and a large duplication encompassing the whole GREM1 gene in a patient with a CRC diagnosed at age 35 [98].