Although the majority of adult MDS is sporadic, pediatric MDS is often associated with inherited bone marrow failure syndromes or more recently identified genetic predisposition syndromes including RUNX1, ANKRD26, ETV6, GATA2, and SAMD9/SAMD9L. Chromosomal losses occur in ∼30% of primary childhood MDS (Niemeyer and Baumann 2008). This evidence concerns the gene RUNX1 and myelodysplastic syndrome.