JARID2 and myeloproliferative disorder: The breakpoint at 6p22.1 associated with the der(6)t(1;6)(q21;p22) in Case no. 3 resulted in a 27 Mb deletion from 6p22.2 to 6pter and encompasses the DEK oncogene as well as JARID2, a member of the polycomb repressor complex 2 cluster of genes known to be implicated in MPN.