The incidence of Lynch syndrome has been estimated to be 1/660–1/2,000 (de la Chapelle, 2005) and approximately 40% of cases are caused by MSH2 mutation (i.e., incidence of MSH2‐Lynch syndrome: 1/1,650–1/5,000) (Moller et al., 2017). Here, MSH2 is linked to Lynch syndrome.