Inv(16) has been reported in 10%~12% of acute myeloid leukemia (AML), mostly being associated with the M4Eo subtype, and is associated with a relatively favorable outcome. However, it is a cryptic rearrangement and often difficult to recognize in conventional cytogenetics (CC). Trisomy 22 is an uncommon karyotypic aberration in AML and is often associated with inv(16)(p13q22). In order to explore the value of trisomy 22 in the diagnosis of AML with inv(16), dual-color interphase fluorescence in situ hybridization (FISH) was performed in 19 AML cases with trisomy 22 abnormality. The probe was two-color break apart probe for CBFb with SpectrumRed on the centromeric side and SpectrumGreen on the telomeric side. And the results were compared with that of R-banding CC. CC did not reveal inv(16) in any of the 19 AML with trisomy 22, but FISH analysis showed inv(16) in 11 cases and del(16)(q22) in one case. Among 11 cases with inv(16), 9 were trisomy 22 as the sole abnormality, one was complicated with trisomy 8, and one was del(16)(q22). Four AML patients with trisomy 22 and inv(16) were analyzed by multiplex FISH (M-FISH) which revealed trisomy 22 only. This study further confirmed that trisomy 22 as the sole abnormality can be regarded as an important marker for the inv(16) in AML.

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