Ring Chromosome 5 in acute myeloid leukemia defned by whole-genome single nucleotide polymorphism array

Chromosomes forming a corresponding ring cannot be clearly defned by conventional cytogenetics or FISH. Karyotypic analyses using whole-genome single nucleotide polymorphism arrays (SNP-A) may result in the identifcation of previously cryptic lesions and allow for more precise defnition of breakpoints. We describe a case of AML with metaphase cells bearing -5, del(11)(q22), and +r. With SNP-A, a 5p-terminal deletion (11 megabases [Mb]), a 5q-terminal deletion (27 Mb), an 11q-interstitial deletion (29 Mb), and a 21q gain (3 Mb) were identifed. Therefore, the G-banded karyotype was revised as 46, XY, r(5)(p15. 2q33.2), del(11)(q14.1q23.2), dup(21)(q22.13q22.2)[18]/46, XY[2]. SNP-A could be a powerful tool for characterizing ring chromosomes in which the involved chromosomes or bands cannot be precisely identifed by conventional cytogenetics or FISH.