Anti-autoimmune susceptibility 1 antibodies enable researchers to detect and measure the autoimmune susceptibility 1 antigen in biological samples. This target is a reported synonym of the FOXD3 gene, which encodes forkhead box D3. This protein is known to function in the morphogenesis of anatomical structure and cell differentiation, among other biological roles. The human version of autoimmune susceptibility 1 has a canonical amino acid length of 478 residues and a protein mass of 47.6 kilodaltons. It is reported to be localized in the nucleus of cells.