Purpose: Familial clusters of either myelodysplasia (MDS) or myelofibrosis (MF) are well documented although uncommon. The inheritance of a somatic driver mutation presumably accounts for these kindreds, and DNA sequencing has revealed multiple candidate mutations (JAK2, ASXL1, TET2, EZH2, SRSF2) that are shared across the spectrum of these disorders. Given this overlap of nonrandom mutations in MDS and MF, it is surprising that clusters of both MDS and MF within the same family seem to be very rare. Recently, however, we observed a woman with MDS who reported a deceased sibling with MDS and a deceased paternal uncle with MF.
Methods: A careful family history and a review of the medical records, archived pathology, and clinical course were performed and compared with that of the index case.
Results: The index case is a woman aged 49 years presenting with severe anemia in July 2013. A bone marrow (BM) biopsy was mildly hypocellular with reduced erythroid maturation, dyspoietic hypolobated megakaryocytes and no increase in blasts. Cytogenetics revealed an isolated del(5)(q13q31) (in 20/20 cells) with del(7q) in 3/20 cells. Lenalidomide therapy resulted in initial transfusion independence. The deceased brother presented April 1994 with weakness at age 39. A CBC showed pancytopenia with a few blasts and nucleated rbc. A BM biopsy revealed predominantly extreme erythroid megaloblastosis with marked nuclear atypia, hypolobated megakaryocytes without fibrosis, mildly dyspoietic myeloid maturation, and 5% nonerythroid CD34+ blasts. Complex cytogenetic changes included monosomy 7 and der(5), likely a functional 5q deletion or duplication. Despite transfusion support, the patient died of infection and CNS hemorrhage after several months. The paternal uncle presented in June 1996 at age 60 with anemia. The CBC showed leukoerythro-blastosis with prominent dacrocytes, mild thrombo-cytopenia but no dyspoiesis. A BM biopsy revealed marked fibrosis, prominent osteosclerosis, and large hyperlobated hyperchromatic megakaryo-cytes. Overall the history, blood, and biopsy findings were consistent with primary MF but not MDS with fibrosis. Death occurred after 3 years of transfusion support.
Conclusions: Despite the extreme rarity of reported MDS and MF cases within a single family, the kindred reported here suggests the existence of an inherited gene defect that increases the risk of developing either MDS or MF. Presumably, the onset of clinically evident disease and its eventual phenotype is determined by the accumulation of additional different secondary genetic changes. The lack of disease in 6 other siblings and the deceased father aged 75 years, however, argues that any hypothetical driver mutation has incomplete penetrance, ie, a reduced likelihood of either disorder developing within a lifetime. Moreover, since this report cannot rule out either chance alone or a common environmental etiology despite substantial age and household differences, DNA sequencing studies will be necessary to identify a putative inherited gene mutation driving the development of both MDS or MF in this unusual kindred.