Monosomal karyotype in myelodysplastic syndromes, with or without monosomy 7 or 5, is prognostically worse than an otherwise complex karyotype.

Monosomal karyotype (MK) refers to the presence of two or more distinct autosomal monosomies or a single monosomy associated with a structural abnormality. In acute myeloid leukemia, MK has been shown to be prognostically worse than an otherwise complex karyotype. The current study examines whether the same holds true for myelodysplastic syndromes (MDS). A total of 127 MDS patients (median age 70 years) with a complex karyotype were considered; 106 (83%) met the above-stipulated criteria for MK and 21 (17%) had a complex karyotype without monosomies. Survival was significantly inferior in patients with MK compared with those with a complex karyotype without monosomies (P=0.01; HR 1.9, 95% confidence interval (95% CI), 1.1-3.3). Multivariable analysis identified MK (P=0.002), advanced age (P=0.0004) and bone marrow blast percentage (0.04) as independent risk factors for survival. There was no difference in survival among MK patients further substratified by the presence or absence of monosomy 7 and/or monosomy 5. Although not statistically significant, leukemia-free survival was also worse with MK compared with complex karyotype without monosomies (P=0.09; HR 2.7, 95% CI 0.8-9.0). MK in MDS identifies a prognostically worse subgroup of patients with a complex karyotype, regardless of whether monosomy 7 or 5 is part of the MK component.