Monosomal karyotype of chromosome 5/7 was an independent poor prognostic factor for Chinese myelodysplastic syndrome patients.

Monosomal karyotype (MK) was defined as the presence of at least 2 autosomal monosomies or of a single monosomy associated with at least one additional structural abnormality. 6.4-16.3% myelodysplastic syndrome (MDS) patients were reported to fulfill the criteria for MK and associated with poor prognosis in the majority of patients with MDS. In order to further clarify the prognostic significance of MK in Chinese MDS patients, 2080 primary patients were retrospectively analyzed in our center. MK was observed in 8.1% patients (168/2080), and monosomies of chromosome 5/7 were the most frequent types of MK. We further found that MK was significantly associated with elderly patients, higher bone marrow blasts and relatively poor cytogenetics. In addition, MDS patients with MK (n = 59) had poor survival than those without MK (n = 491) in total cohort (P < 0.001), and there was significant difference in the OS between the patients with MK (n = 56) and without MK (n = 53) in the relatively poor cytogenetics group (P = 0.0025). Incorporation of MK into IPSS-R could further stratify MDS patients into different prognostic groups (P < 0.001). Interestingly, monosomies of chromosome 5/7 rather than MK were significantly related to shorter OS (HR = 2.709, P < 0.001) by multivariate analysis. In conclusion, our results suggested that 8.1% MDS patients were presented with MK, and the incidence of MK increased with the number of cytogenetic abnormalities. Monosomies of chromosome 5/7 were the most frequent MK as well as an independent poor risk factor for OS in Chinese MDS patients.