Familial acute myeloid leukemia (AML) caused by inherited CEBPA variants is traditionally considered a favorable-risk form of leukemia. However, by analyzing patients from our institution together with all previously reported families worldwide, we found that not all inherited CEBPA variants behave the same way. The location of the variant within the CEBPA gene strongly influenced the age at disease onset, treatment response, and long-term survival. In particular, variants involving the TAD2 region were associated with older onset, lower remission rates, and significantly worse survival. These findings challenge the assumption that all familial CEBPA-mutated AML has a good prognosis and highlight the importance of precise genetic classification for risk assessment, surveillance, genetic counseling, and treatment decision-making in hereditary leukemia. (https://jmg.bmj.com/content/63/9/596)