Does MDS with der(1;7)(q10;p10) constitute a distinct risk group? A retrospective single institutional analysis of clinical/pathologic features compared to -7/del(7q) MDS.

The der(1;7)(q10;p10) aberration is observed in about 1-3% of the myelodysplastic syndromes (MDS) and less commonly in acute myeloid leukemia (AML) and the myeloproliferative disorders. This unbalanced translocation is considered a "variant" of the del(7q)/-7 subgroup and has been assigned a poor risk karyotype score in the MDS International Prognostic Scoring System (IPSS). Recent reports suggest der(1;7) MDS should be considered a discrete MDS subgroup with an intermediate, not poor, karyotype score. At the City of Hope, we compared the clinical-pathologic features of 12 der(1;7) MDS patients to 51 MDS patients with del(7q) (n=10) or -7 (n=41), selected for a similar frequency of secondary aberrations. The der(1;7) patients showed older age at diagnosis, lower platelet counts, less trilineage dysplasia, and lower blast counts. The der(1;7) patients did not differ from del(7q)/-7 patients in subtypes of MDS by World Health Organization, French-American-British classifications, or bone marrow cellularity. Neither the proportion of therapy-related MDS nor the transformation to AML differed significantly among the three subgroups. Five-year survival rates for der(1;7), del(7q), and -7 (44.4, 32.0, and 23.6%, respectively) did not differ significantly (P=0.94). While der(1;7) MDS is associated with some clinically distinctive features, reassignment of risk category based on these data would be premature.