The NM_000546.6: c.532C>G variant in TP53 is a missense variant predicted to cause substitution of histidine by aspartic acid at amino acid 178 (p.His178Asp). This variant has been identified as a de novo occurrence with unconfirmed parental relationships in 1 individual with a strongly-associated LFS-associated cancers totaling 2 phenotype points (PS2_Moderate; PMID 21345075). This variant has been reported in 2 additional unrelated probands meeting revised Chompret criteria. Based on this evidence, this variant scores 1 total point meeting the TP53 VCEP phenotype scoring criteria of 1-1.5 points. (PS4_Supporting; SCV000754561.6, SCV000667198.3). This variant has an allele frequency of 6.195e-7 (1/1614230 alleles) across gnomAD v4.1.0 which is lower than the Clingen TP53 VCEP threshold (<0.00003) for PM2_Supporting, and therefore meets this criterion (PM2_Supporting). In vitro assays performed in yeast and human cells showed non-functional transactivation and loss of growth suppression activity indicating that this variant impacts protein function (PS3; PMIDs: 12826609, 30224644). This variant has five somatic occurrences for the same amino acid change in cancerhotspots.org (v2) sufficient to be defined as a mutational hotspot by the ClinGen TP53 VCEP (2-9 somatic occurrences, PMID: 30311369) (PM1_Supporting). Computational predictor scores (BayesDel =0.4249); Align GVGD = Class C65) are above recommended thresholds (BayesDel ≥ 0.16 and an Align GVGD Class of 65), evidence that correlates with impact to TP53 via protein change (PP3_Moderate). In summary, this variant meets the criteria to be classified as pathogenic for Li Fraumeni Syndrome based on the ACMG/AMP criteria applied, as specified by the ClinGen TP53 VCEP: PS2_Moderate, PS4_Supporting, PM2_Supporting, PS3, PM1_Supporting, PP3_Moderate. (Bayesian Points: 11; VCEP specifications version 2.0; 7/24/2024)