A recent report identified a truncating genetic variant in ribosomal protein S20 (RPS20), a novel colorectal cancer predisposition gene that encodes a component of the small ribosomal subunit (S20) in familial colorectal cancer type X (FCCX), which is characterized by hereditary nonpolyposis colorectal cancer without mismatch repair abnormalities.26 The gene discussed is RPS20; the disease is familial colorectal cancer type X.