Albinism (from Latin albus, "white"; see extended etymology, also called achromia, achromasia, or achromatosis) is a congenital disorder characterized by the complete or partial absence of pigment in the skin, hair and eyes due to absence or defect of tyrosinase, a copper-containing enzyme involved in the production of melanin. Albinism results from inheritance of recessive gene alleles and is known to affect all vertebrates, including humans. While an organism with complete absence of melanin is called an albino ( /ælˈbaɪnoʊ/ American English, or /ælˈbiːnoʊ/ British English) an organism with only a diminished amount of melanin is described as albinoid. Albinism is associated with a number of vision defects, such as photophobia, nystagmus and astigmatism. Lack of skin pigmentation makes for more susceptibility to sunburn and skin cancers. In rare cases such as Chediak Higashi Syndrome, albinism may be associated with deficiencies in the transportation of melanin granules. This also affects essential granules present in immune cells leading to increased susceptibility to infection. In humans, there are two principal types of albinism, oculocutaneous, affecting the eyes, skin and hair, and ocular affecting the eyes only. Most oculocutaenous albinistic humans appear white or very pale as the melanin pigments responsible for brown, black, and some yellow colorations are not present. Ocular albinism results in pale blue eyes, and may require genetic testing to diagnose.