Somatic genetic rescue mutations that promote telomere elongation are protective of developing MDS/AML in the short telomere syndromes.TERT promoter mutations arise in trans with the germline TERT loss-of-function mutation and upregulate transcription of the wild-type TERT. POT1 mutations are a more universal rescue mechanism with no preference for germline mutant gene, and POT1 loss-of-function mutation improves telomerase access to the telomere and/or increases telomerase processivity. Monosomy 7 and biallelic TP53 mutations, also shared risk factors in other BMF/MDS syndromes, are associated with progression to MDS/AML. Chr, chromosome; WT, wild type.