Ring chromosome 5 in acute myeloid leukemia defined by whole-genome single nucleotide polymorphism array

Area of Science:

• Genetics
• Molecular Biology
• Cancer Research

Background:

• Conventional cytogenetics and fluorescence in situ hybridization (FISH) often struggle to clearly define ring chromosomes.
• Karyotypic abnormalities are crucial for diagnosing and classifying hematological malignancies, including acute myeloid leukemia (AML).

Observation:

• A case of AML presented with metaphase cells exhibiting specific chromosomal abnormalities: loss of chromosome 5 (-5), deletion on chromosome 11 (del(11)(q22)), and a ring chromosome (+r).
• Whole-genome single nucleotide polymorphism arrays (SNP-A) were employed for detailed karyotypic analysis.

Findings:

• SNP-A identified previously cryptic chromosomal lesions, including a 5p-terminal deletion (11 Mb), a 5q-terminal deletion (27 Mb), an 11q-interstitial deletion (29 Mb), and a 21q gain (3 Mb).
• The G-banded karyotype was revised to 46, XY, r(5)(p15.2q33.2), del(11)(q14.1q23.2), dup(21)(q22.13q22.2)[18]/46,XY[2], providing a more precise definition of breakpoints and rearrangements.
• These findings highlight the limitations of conventional methods in fully characterizing complex chromosomal structures like ring chromosomes.

Implications:

• Single nucleotide polymorphism arrays (SNP-A) offer a powerful tool for accurately characterizing ring chromosomes and cryptic chromosomal aberrations.
• Enhanced precision in defining chromosomal breakpoints can lead to improved diagnostic accuracy and potentially guide therapeutic strategies in AML and other genetic disorders.
• This approach advances the field of cytogenetics by enabling a more comprehensive understanding of complex chromosomal rearrangements.