Novel Germline RUNX1 Mutation Associated with Familial Thrombocytopenia as well as B-Acute Lymphoblastic Leukemia: A Case Report and Review of the Literature.

Germline mutations lead to a rare form of autosomal-dominant familial thrombocytopenia with a predisposition for myeloid malignancies and are classified as distinct entities by the WHO. We report a case of B lymphoblastic leukemia developing in a patient with a familial mutation, which is a first in the literature. An -ITD mutation as well as a balanced chromosomal translocation t(1;7) was present at the time of diagnosis of leukemia, favoring the theory that additional hits or mutations are necessary for malignant transformation in patients with a germline mutation. The transformed disease runs an aggressive course compared to the same malignancy associated with a somatic mutation. Additionally, family members should be screened for the mutation, followed up clinically if they carry the mutation, and should not be used as stem cell donors to treat the affected relatives.