[Cytogenetic study of autosomal monosomies among myelodysplastic syndrome patients]

Monosomic karyotype (MK) has recently been associated with poor prognosis of myelodysplastic syndromes (MDS). The objective of the current study was to investigate the prevalence and spectrum of autosomal monosomies in an unselected cohort of patients with known or suspected MDS by using retrospective analysis. The results showed that bone marrow cytogenetic studies (1532 cases) were performed between 2004 and 2012, and an abnormal karyotype was found in 538 cases (35.1%). In the 538 cases, 202 (37.5%) cases had autosomal monosomies including sole (n = 47, 23.3%), part of two (n = 33, 21.3%) or more (n = 122, 78.7%) anomalies. Almost all 22 autosomes were involved, but monosomy 7 was by far the most frequent, constituting 66.1% of all isolated monosomies and the highest fraction of those with two or more abnormalities. Other recurrent sole monosomies included chromosomes 20 (15.0%) and 13 (8.5%). Monosomy 13 (12.5%), 18 (8.3%), 20 (6.3%), 17 (7.3%), 21 (5.2%), 5 (5.2%) and 12 (5.2%) were also recurrent in the setting of 3 abnormalities. Bone marrow histology and clinical information were reviewed in all cases with isolated monosomy; associated clinical phenotypes were found in RCMD (n = 20, 13 were -7), RAEB (n = 12, 11 were -7), RA (n = 9, 3 were -7) and chronic myelomonocytic leukemia (CMML, n = 6, 4 were -7) cases. Sole monosomy 20 (n = 7, RA 3 case and RCMD 4 cases) was not detected in RAEB or CMML cases. It is concluded that the presence of at least 1 autosomal monosomy was documented in approximately 37.5% of all abnormal cases, which has potential impact on a more than trivial fraction of patients with MDS. The preponderance of monosomy 7 implicates a pathogenetic role for haploinsufficiency of genes associated with chromosome 7. The rarity of sole monosomy involving other chromosomes other than 7, 20, and 13 suggests that haploinsufficiency involving entire chromosomes is detrimental to cell survival, unless their effect is overcome by the presence of other genetic changes that are often associated with additional chromosomal abnormalities. The observation is consistent with the usually favorable prognostic profile associated with sole monosomy 20.