CCDC68, also known as CTCL tumor antigen se57-1, is a 335 amino acid protein expressed in cutaneous T-cell lymphoma (CTCL), bone marrow, colon, small intestine, spleen, testis and trachea tissues. CTCL is a cancer of the immune system associated with mutation of the T cells. Malignant T cells form lesions on the surface of the skin. se57-1 contains 1 coiled coil domain and is encoded by the CCDC68 gene mapping to human chromosome 18. Chromosome 18 houses over 300 protein-coding genes and contains nearly 76 million bases. There are a variety of diseases associated with defects in chromosome 18-localized genes, some of which include Trisomy 18 (also known as Edwards syndrome), Niemann-Pick disease, hereditary hemorrhagic telangiectasia, erythropoietic protoporphyria and follicular lymphomas.