[The study on relationship between age and cytogenetic subgroups in 640 patients with de novo acute myeloid leukemia]

To analyze the cytogenetic characteristics of different age subgroups in patients with acute myeloid leukemia (AML), and to explore the relationship between age and cytogenetics.

Between January 2004 and December 2011, Bone marrow (BM) samples from 640 patients with de novo AML were analyzed retrospectively. The analyses were performed according to standard culturing and banding techniques, and clonal abnormalities were defined and described according to the International System for Human Cytogenetic Nomenclature (ISCN 2009). The cytogenetic subtypes were performed as normal, balanced, and unbalanced karyotypes. In the last group, the age distribution of complex and monosome karyotypes were further analyzed. The patients were divided into 8 age groups: 0 - 9, 10 - 19, 20 - 29, 30 - 39, 40 - 49, 50 - 59, 60 - 69, and ≥ 70 year old groups.

The distribution of normal, balanced, and unbalanced karyotypes showed age specific characteristics. The incidence of normal karyotype increased from 6.67% (0 ∼ 9 year old) to 58.33% (≥ 70) (χ(2) = 20.68, P = 0.001) and balanced karyotype decreased from 73.33% (0 ∼ 9) to 11.11% (≥ 70) (χ(2) = 48.22, P < 0.01). The frequency of unbalanced karyotypes increased from 20.0% (0 ∼ 9) to 30.56% (≥ 70) (χ(2) = 18.963, P = 0.008). The frequency of complex karyotype was 6.67% in 0 - 9 year old group, followed by 0% in 10 - 19 and 20 - 29 year old group, and from 1.72% to 11.11% from 30 - 39 to ≥ 70 year old group (χ(2) = 8.341, P = 0.08). Monosome karyotype was only detected in patients in 30 year old or older groups. Although an increased tendency was observed with ages, there was no significant difference (χ(2) = 4.778, P = 0.311).

The different age profiles of the cytogenetic subtypes may indicate the different mechanisms of the pathogenesis of AML, which may also offer beneficial information for etiological research of AML.