Effect of mutations on the structure of GFI1b. (A) Schematic structure of zinc finger 5 of Gfi1b and localization of the 2 mutations (Q287* and H294fs) found in families with inherited “bleeding disorder platelet-type, 17” (BDPLT17; OMIM 187900) or “Gfi1b-related thrombocytopenia” (GFI1B-RT). (B) The missense Q287* mutation introduces a premature stop codon in GFI1B causing a truncation and loss of the α helix strand in the third zinc finger domain in GFI1b (arrow).