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Specialized technique effective in identifying chromosomal abnormalities, improving prognosis for MDS

Original Publication Date: 
Tuesday, July 31, 2012

Note: This abstract was presented at the 2012 ASCO annual meeting in June 2012. The full abstract may be reviewed on the ASCO Annual Meeting Web site. Use the abstract number to access the full report.

Abstract # 6521

To date, the most widely used prognostic classification system for myelodysplastic syndrome (MDS) is the International Prognostic Scoring System (IPSS). The first IPSS was derived from a study published in 1997. The IPSS separates patients into four distinct subgroups based solely on the percentage of bone marrow blasts, cytogenetics (branch of genetics which studies the chromosomes), and the number of cytopenias (reduction in the number of blood cells). Due to several limitations of the first IPSS, new cytogenetic categories were developed for a revised IPSS (IPSS-R) in 2012. The IPSS-R changes include: a larger number of cytogenetic abnormalities which are given more weight than previously, different cut-offs for blast percentage, and sensitivity to degrees of cytopenias.

Furthermore, cytogenetics in patients with MDS is extremely important. The current standard of detecting chromosomal rearrangements is through metaphase cytogenetics. Metaphase cytogenetics means studying chromosomes in the middle of the cell cycle (during a specific time when the cell is actively dividing). This can be very difficult, as it requires dividing cells. It only provides a “low resolution” of the chromosome and is unable to detect certain chromosomal abnormalities.  

The team from the Cleveland Clinic (Manojkumar Bupathi and colleagues) utilizes single nucleotide polymorphism arrays (SNP-A) to better detect these chromosomal abnormalities. SNP-A is a method to detect a variation in the DNA at a single site. When compared to the conventional method of metaphase cytogenetics, SNP-A is similar to “zooming in” and looking at the molecular make-up of the chromosome. In a previous study by Dr. Ramon Tiu from the Cleveland Clinic, SNP- A is a technology that has been shown to detect uniparental disomy (UPD) and cryptic chromosomal abnormalities.

The goal of this particular study is to incorporate the type of SNP-A lesions with current prognostication models – both the IPSS and IPSS-R. The study found that the chromosomal abnormalities identified from SNP-A can be divided into specific subgroups. When these categories are combined with the IPSS and IPSS-R, MDS risk stratification can be further refined. This abstract reveals that the SNP-A has significant prognostic implications in MDS.

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