DOM3Z, also known as NG6 or DOM3L, is a 396 amino acid ubiquitously expressed protein belonging to the Dom3Z family. The gene encoding DOM3Z maps to human chromosome 6 in the major histocompatibility complex (MHC) class III region. Chromosome 6 contains 170 million base pairs and comprises nearly 6% of the human genome. Deletion of a portion of the q arm of chromosome 6 is associated with early onset intestinal cancer, suggesting the presence of a cancer susceptibility locus. Additionally, Porphyria cutanea tarda, Parkinson's disease and Stickler syndrome are all associated with genes that map to chromosome 6.