We present the case of a 55-year-old male who received an allogeneic hematopoietic stem cell transplant (HSCT) from an HLA-matched sibling donor for acute myeloid leukemia/myelodysplastic syndrome (AML/MDS) with TP53 mutation, seven years after a lung transplant. The gene discussed is TP53; the disease is myelodysplastic syndrome.