Single-nucleotide polymorphism array-based karyotyping of acute promyelocytic leukemia

Area of Science:

• Hematology
• Cancer Genetics
• Molecular Biology

Background:

• Acute promyelocytic leukemia (APL) is primarily defined by the t(15;17) translocation.
• Additional chromosomal abnormalities (ACAs) can influence leukemic phenotype but are often missed by conventional methods.

Purpose of the Study:

• To investigate sub-detectable ACAs in APL using high-resolution SNP arrays.
• To identify novel genetic events contributing to APL development.

Main Methods:

• High-resolution SNP array (SNP-A 6.0) analysis was performed on 48 APL patients (diagnosis and remission samples).
• Acquired copy-number abnormalities (CNAs) and copy-neutral loss of heterozygosity (CN-LOH) were identified.

Main Results:

• 48% of patients (23/48) exhibited acquired abnormalities, including duplications, deletions, and CN-LOH.
• Dup(8q24) and del(7q33-qter) were the most frequent CNAs.
• Recurrent ACAs, excluding dup(8q24) and del(7q33-qter), were infrequent but common among themselves (70%).
• CNAs and FLT3 mutations were mutually exclusive.

Conclusions:

• High-resolution SNP arrays detect recurrent genetic abnormalities in APL beyond t(15;17).
• These secondary events may explain leukemogenesis in up to 40% of APL cases lacking ACAs by conventional cytogenetics.
• No significant association was found between CNA number/type and prognosis.