RUNX1 and Congenital thrombocytopenia: Germline variants causing haploinsufficiency including nonsense, frameshift variants and de novo microdeletion (covering entire locus or just the MDS1 coding regions) causes congenital thrombocytopenia but not skeletal abnormalities (131) whereas missense variants in the ZF2 domain affecting the MDS1-EVI1 and EVI1 transcripts cause limb defects and thrombocytopenia including radioulnar synostosis with amegakaryocytic thrombocytopenia 2 (RUSAT2; OMIM #616738).