MDS patient registries - achievements and challenges.

Since the late 1980s, patient registries have played a pivotal role in the elucidation of rare diseases. For myelodysplastic syndromes (MDS), they revealed the disease actually to be diverse rather than rare. Registry data enabled the definition of various MDS subtypes and prognostic scores tailoring therapy. These classifications have been revised and refined several times, and the differential diagnosis of MDS has become increasingly complex. At the same time, the diagnosis has been made more commonly and no longer by specialized centers of expertise only. Consequently, several registries have collected data with different focuses and from different patient subpopulations. The current review presents three MDS registries and their rationale, scope, design, and achievements. All three complement each other and will remain a mainstay to advance the knowledge on MDS as well as to validate the outcomes of clinical trials. However, delineation of subtypes after the most recent WHO and IPC revisions, as well as the determination of the newest risk score M of the International Prognostic Scoring System (IPSS-M), no longer just shift cut-offs but are based on multivariate compilations of highly specific genetic information. This paradigm shift involves challenging registries with respect to the assignment of all patients for whom this information has not yet been available.