Monosomy X as a recurring sole cytogenetic abnormality associated with myelodysplastic diseases

Solitary loss of the X chromosome is associated with Turner syndrome and not hematological disorders. We describe five patients with non-constitutional loss of the X chromosome as the sole cytogenetic abnormality in their bone marrow. Three of the five patients had myelodysplastic syndrome (MDS), one case had AML M-6 with evidence suggestive of an evolving MDS, and the last patient had a dysplastic marrow. A review of the literature identified sporadic reports of an association of monosomy X and several hematologic disorders, as well as a few solid tumors. In this series of patients, monosomy X as a sole non-constitutional cytogenetic abnormality in bone marrow is associated with myelodysplastic diseases. In addition, fluorescence in situ hybridization analysis with an X centromere probe indicated that monosomy X was present in erythroid precursors, myeloblasts, promyelocytes, myelocytes, metamyelocytes, granulocytes, and monocytes, while mature lymphocytes presented with two copies of the X chromosome. The molecular cytogenetic evidence supports the diagnosis of a myelodysplastic disorder in these cases and documents the potential role of FISH in hematological diseases.