Oculocutaneous albinism (OCA) is a complex genetic disease with great clinical heterogeneity. Four different types of OCA have been reported to date (OCA1, OCA2, OCA3, and OCA4). OCA4 was firstly reported in a Turkish OCA patient. The gene responsible for OCA4 is the human homologue of the mouse underwhite (uw) gene, which encodes the mem-brane-associated transporter protein (MATP). MATP gene is located on chromosome 5p13.3 and is divided into 7 exons and 6 introns. MATP gene is transcriptionally modulated by MITF, and encodes a protein of 530 amino acids. There are at least 18 pathologic mutations and 8 non-pathologic polymorphisms have been found.