Gel mobility shift assays show loss of nuclear protein binding with a mutant factor VII promoter sequence (MT94) from a patient with severe factor VII deficiency. A radiolabeled wild-type (WT) oligonucleotide including the Sp1 binding site (−108 to −84 bp before the translation start site) in the human factor VII promoter region showed binding to proteins (arrows) from HeLa nuclear extracts (lane 1). Specificity of binding is shown by competition with unlabeled WT oligonucleotide sequence at 10×, 100×, and 500× concentrations (lanes 2, 3, and 4) but not with an oligonucleotide having the mutant sequence (lanes 5, 6, and 7). Lanes 8 through 14 show the lack of binding of nuclear proteins by complexes labeled Sp1, B, and D to radiolabeled probe containing the MT94 sequence.