Myelodysplastic syndrome (MDS) is not a disease that follows a standard path; especially time of survival after diagnosis and the risk to develop leukemia is highly variable among patients. It is therefore believed that MDS represents not one but a group of diseases. Indeed, there are several systems in place that allow doctors to classify MDS into particular subtypes based on a pre-determined set of diagnostic criteria; there is the French-American-British (FAB) and the World Health Organization (WHO) classification. These classification systems describe the cellular nature and genetic abnormality of the disease, but are not indicative of the seriousness of the disease. The latter is provided by the International Prognostic Scoring System (IPSS). The newest version of IPSS classifies people in 5 categories, from categories with a very poor to a very good predicted outcome. This classification system is helpful in that it suggests what path the disease may follow (e.g., aggressive with very high likely hood to develop into leukemia, or e.g., very mild with a low risk to progress into leukemia) and can therefore help in deciding the type of treatment necessary for a particular patient. However, these classification systems tell us very little about the underlying mechanisms of disease development and progression.
There are several examples of recent studies that have begun to unravel the correlation between disease outcome and disease mechanisms. One such example is the recent discovery of alterations in a gene (named SF3B1) that encodes a protein necessary for the final stages of protein production. MDS patients with this type of gene alteration had a low risk of progression to leukemia and longer survival time compared to MDS patients without this gene alteration. It is important to correlate disease outcome with disease mechanisms, because this would allow us to learn more about the causes of MDS at a molecular level, which will help us to develop individualized (patient-specific) therapies that are likely to be more successful.