Autosomal monosomies among 24,262 consecutive cytogenetic studies: Prevalence, chromosomal distribution and clinicopathologic correlates of sole abnormalities

Monosomal karyotype (MK) has recently been associated with poor prognosis in acute myeloid leukemia (AML), myelodysplastic syndromes (MDS), and primary myelofibrosis (PMF). The objectives of the current study were to describe the prevalence and spectrum of autosomal monosomies in an unselected cohort of patients with known or suspected hematologic malignancies. Bone marrow cytogenetic studies (24,262) were performed at our institution between 1989 and 2009. An abnormal karyotype was demonstrated in 6,565 cases (∼27%); of these, 1,365 (∼21%) included autosomal monosomies that occurred as sole (n = 133; ∼10%), part of two (n = 82; ∼6%) or more (n = 1,150; ∼84%) anomalies. All 22 autosomes were involved, but monosomy 7 was by far the most frequent, constituting ∼80% of all isolated monosomies and the highest fraction of those with two or more abnormalities. Other recurrent sole monosomies included chromosomes 20 (∼11%) and 21 (∼4%). Monosomy 13 (∼10%), 20 (∼8%), 18 (∼7%), 17 (∼6%), 21 (∼5%), 5 (∼5%), and 12 (∼4%) were also recurrent in the setting of ≥2 abnormalities. Bone marrow histology and clinical information were reviewed in all cases with isolated monosomy; associated clinical phenotypes were MDS (n = 60; 52 were -7), AML (n = 32; 31 were -7), myeloproliferative neoplasms (n = 16; 10 were -7), chronic myelomonocytic leukemia (CMML; n = 10; 9 were -7) and other nonmyeloid malignancies (n = 15; 4 were -7). Sole monosomy 20 (n = 14; six MDS, five MPN, and three nonmyeloid) was not seen in AML or CMML. Sole monosomy 21 was more frequent in nonmyeloid as opposed to myeloid cases.