While deletion 5q and SF3B1 mutation most clearly demonstrate the relationship of genotype to phenotype, there are a variety of other mutations that are associated with an MDS phenotype including idic(X)(q13), isochromosome 17q, 17p deletion or loss of 17p, monosomy 13 or 13q deletion, 12p deletion or loss of 12p, 11q deletion, monosomy 7, 7q deletion, or loss of 7q, complex karyotype, and pathologic mutations in ASXL1, BCOR, EZH2, SRSF2, STAG2, U2AF1, and ZRSR2 (8, 12). This evidence concerns the gene U2AF1 and myelodysplastic syndrome.