The observation that TP53 disruption restores bone marrow repopulation capacity to RPS19+/– HSCs raises the possibility that selective pressure could expand DBA patient HSPCs with somatic loss-of-function TP53 mutations, analogous to what occurs in other bone marrow failure disorders, including Shwachman-Bodian-Diamond syndrome (72), Fanconi anemia (73), and dyskeratosis congenita (74). The gene discussed is TP53; the disease is dyskeratosis congenita.