Single-nucleotide polymorphism array (SNP-A) improves the identification of chromosomal abnormalities by metaphase cytogenetics in myelodysplastic syndrome.

Aims: The myelodysplastic syndromes (MDS) are a heterogeneous group of clonal haematopoietic stem cell disorders characterised by inefficient haematopoiesis and risk of progression to acute myeloid leukaemia. Metaphase cytogenetics is an extremely valuable clinical tool in the management of haematological malignancies. However, metaphase cytogenetics requires cellular proliferation, its sensitivity and resolution depends on the proportion of clonal cells in the sample and size of the lesion, respectively. Single-nucleotide polymorphism array (SNP-A) does not depend on the presence of dividing cells, is able to detect copy number variations with a high resolution and to detect copy number neutral loss of heterozygosity or uniparental disomy (UPD). The aim of this study was to illustrate that the use of SNP-A can cover cryptic chromosomal lesions not identified by metaphase cytogenetics in patients with MDS.

Methods: Metaphase cytogenetics was performed on bone marrow aspirate using standard methods. Genomic DNA from total bone marrow cells were submitted to SNP-A using Affymetrix Genome-Wide Human SNP CytoScan HD.

Results: In our cohort of 15 patients with a diagnosis of MDS and related diseases, chromosomal abnormalities were found in 47% of the cases by SNP-A and in 33% by metaphase cytogenetics. SNP-A detected all lesions identified by metaphase cytogenetics, except a balanced translocation and a marker chromosome. Notably, SNP-A detected a total of 30 new lesions: 1 (3%) gain, 17 (57%) losses and 12 (40%) UPDs in 5 patients with MDS.

Conclusions: SNP-A may complement metaphase cytogenetics to improve the detection of chromosomal abnormalities in myeloid neoplasms.