A novel RUNX1 germline mutation found in a pedigree of familial AML. (A) A family tree. Closed symbols indicate individuals with AML. Patient II-1 had AML (M1), patient II-2 had refractory anemia with excess blasts/AML, and patient II-8 had AML (M2). The proband is indicated by the arrow. Genomic DNA samples from individuals II-1, II-2, II-8, III-1, and III-2 were collected. (B) Sanger sequence analysis of the coding region of RUNX1. All 3 affected individuals had the heterozygous germline G to A mutation, which caused the amino acid change from arginine (AGG) to lysine (AAG). The mutation was not present in the unaffected individuals. (C) The position of the detected R237K mutation in RUNX1. The Runt DNA-binding domain (Runt), the activation domain (AD), and the inhibitory domain (ID) are indicated. The mutated arginine residue was outside the Runt DNA-binding domain and one of the 2 methylation sites (R233 and R237) by PRMT1. (D) Alignments of the region flanking R237 in human RUNX1 with isotypes from various species. Amino acids not conserved between human and other species are shown in red. The region around the mutated residue is highly conserved among species. (E) Alignments of human RUNX1, RUNX2, and RUNX3. Amino acids not conserved are shown in red. The mutated residue is conserved among human RUNX proteins.