Putative serine protease inhibitor. Highly expressed in dendritic cells and primary leukemia cells, especially those of myeloid lineage. Minor histocompatibility antigen ACC-6 (mHA ACC-6) is encoded by HMSD-v which is an allelic variant of HMSD. HMSD-v results from an intronic single-nucleotide polymorphism located at position 5 of HMSD intron 2 leading to a G to A substitution. This variation in intron 2 induces skipping of exon 2 and frameshift, resulting in expression of ACC-6. Belongs to the serpin family. Translation of HMSD-v form generating mHA ACC-6 is in a frame different from that resulting in HMSD non variant form expression. Thus, HMSD sequence described in this entry does not contain the mHA ACC-6 peptide.