TP53 and cancer: Pathogenic variants in TP53 were identified in four patients and three of them harbored the same variant - c.1010G>A (p.Arg337His/R337H), that was introduced in Brazil possibly a founder effect, and is now found in relatively high frequencies in the southeast and southern regions of the country (37). A recent study identified a variant in the tumor suppressor XAF1 (E134*) in a subset of R337H carriers and proposes that the co-segregation of XAF1-E134* and TP53-R337H mutations leads to a more aggressive cancer phenotype than R337H alone (38).