OOEP (oocyte-expressed protein homolog), also known as KHDC2 (KH homology domain-containing protein 2) or OEP19 (oocyte- and embryo-specific protein 19), is a 149 amino acid cytoplasmic protein that belongs to the KHDC1 family and contains one KH domain. As a member of the subcortical maternal complex (SCMC), OOEP is necessary for zygotes to progress beyond the first embryonic cell divisions. In addition to OOEP, the SCMC includes NALP5 and TLE6. The gene that encodes OOEP consists of approximately 26,579 bases and maps to human chromosome 6q13. With 170 million base pairs, chromosome 6 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, Stickler syndrome and a susceptibility to bipolar disorder are all associated with genes that map to chromosome 6.