Teneurin-3, also known as Ten-3, TNM3 or ODZ3, is a 2,699 amino acid single-pass type II membrane protein that contains 25 YD repeats, 8 EGF-like domains, 5 NHL repeats and one teneurin N-terminal domain. Localized to the membrane and expressed in brain, testis and ovary, Teneurin-3 exists as a disulfide-liked homodimer that is thought to function as a cellular signal transducer. Additionally, Teneurin-3 may participate in eye-specific patterning in the visual pathway and is required for aligned binocular vision. The gene encoding Teneurin-3 maps to chromosome 4. Representing approximately 6% of the human genome, chromosome 4 contains nearly 900 genes, one of which is the Huntingtin gene, which is found to encode an expanded glutamine tract in cases of Huntington's disease. 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.