TP53 and cancer: p.R273C (c.817C>T) and p.R273H (c.818G>A) are among the top five most common p53 hotspot mutations, together found in roughly 7% of widespread human cancers.3 Less frequent p.R273 mutations include p.R273L (c.818G>T), p.R273S (c.817C>A), p.R273G (c.817C>G), and p.R273P (c.818G>C).