Synonymous mutation in TP53 results in a cryptic splice site affecting its DNA‐binding site in an adolescent with two primary sarcomas

Pathologic variants in TP53 are known risk factors for the development of cancer. We report a 17-year-old male who presented with two primary sarcomas. Germline sequencing revealed a novel TP53 c.672 G>A mutation. Sequencing revealed wild-type TP53 in the parents, and there was no history of cancer in first-degree relatives. This de novo synonymous germline mutation results in a 5′ cryptic splice site that is bound by U1, resulting in a shift of the splice site by 5 base pairs. The frame shift results in a truncated protein at residue 246, which disrupts the DNA-binding domain of p53.