Familial Essential Thrombocythemia With Novel MPL L502G and G208K Mutations.

Familial essential thrombocythemia is characterized by the inheritance of germline mutations to progeny, thereby increasing the risk for the development of essential thrombocythemia. Here, we present two cases of young women who developed thromboembolic phenomena, one of whom with an ischemic event despite adequate anticoagulation. Through extended mutational testing, both were characterized as having novel mutations in the myeloproliferative leukemia virus (MPL) gene, and both individuals have fathers being treated for essential thrombocythemia. This case provides insight that in familial essential thrombocythemia, there remain uncharacterized mutations in this inherited conditional landscape.