PLAC8 is a 115 amino acid protein belonging to the cornifelin family that is expressed at high levels in plasmacytoid dendritic cells and other organs of the immune system including lymph nodes, spleen, bone marrow and peripheral blood leukocytes, with lower expression in appendix, thymus and fetal liver. Human PLAC8 shares 83% homology with murine PLAC8, where it has been identified in placenta from 9.5-18.5 days postcoitum. The gene encoding PLAC8 maps to human chromosome 4, which represents approximately 6% of the human genome and contains nearly 900 genes. Notably, the Huntingtin gene, which is found to encode an expanded glutamine tract in cases of Huntington's disease, is on chromosome 4. FGFR-3 is also encoded on chromosome 4 and has been associated with thanatophoric dwarfism, achondroplasia, Muenke syndrome and bladder cancer. Chromosome 4 is also tied to Ellis-van Creveld syndrome, methylmalonic acidemia and polycystic kidney disease