ST18 is a 1,047 amino acid nuclear protein that is expressed at low levels in heart, liver, kidney, skeletal muscle, pancreas, testis, ovary and prostate. Containing six C2HC-type zinc fingers and an SMC domain, ST18 is a repressor protein that binds to DNA sequences containing a specific bipartite element. ST18 is considered a transcription factor that represses basal transcription activity from target promoters and Inhibits colony formation in cultured breast cancer cells. ST18 is encoded by a gene located on human chromosome 8, which consists of nearly 146 million base pairs, encodes over 800 genes and is associated with a variety of diseases and malignancies. Schizophrenia, bipolar disorder, Trisomy 8, Pfeiffer syndrome, congenital hypothyroidism, Waardenburg syndrome and some leukemias and lymphomas are thought to occur as a result of defects in specific genes that map to chromosome 8.