Oculocutaneous albinism
Encyclopedia
Oculocutaneous albinism is a form of albinism
involving the eye
s ("oculo-"), skin
("-cutaneous"), and in rare instances, the hair
as well.
Four types of oculocutaneous albinism have been described, all caused by a disruption of melanin
synthesis and all autosomal recessive disorders.
Common Albinism requires genes from both parents, while Oculocutaneous albinism only need a gene directly from a mother to her son.
Albinism
Albinism 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 an enzyme involved in the production of melanin...
involving the eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
s ("oculo-"), skin
Human skin
The human skin is the outer covering of the body. In humans, it is the largest organ of the integumentary system. The skin has multiple layers of ectodermal tissue and guards the underlying muscles, bones, ligaments and internal organs. Human skin is similar to that of most other mammals,...
("-cutaneous"), and in rare instances, the hair
Hair
Hair is a filamentous biomaterial, that grows from follicles found in the dermis. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class....
as well.
Four types of oculocutaneous albinism have been described, all caused by a disruption of melanin
Melanin
Melanin is a pigment that is ubiquitous in nature, being found in most organisms . In animals melanin pigments are derivatives of the amino acid tyrosine. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms...
synthesis and all autosomal recessive disorders.
Common Albinism requires genes from both parents, while Oculocutaneous albinism only need a gene directly from a mother to her son.
Types
| Name | OMIM | Gene | Description |
| TYR Tyrosinase Tyrosinase also known as monophenol monooxygenase is an enzyme that catalyses the oxidation of phenols and is widespread in plants and animals... |
tyrosinase Tyrosinase Tyrosinase also known as monophenol monooxygenase is an enzyme that catalyses the oxidation of phenols and is widespread in plants and animals... gene, and can occur in two variations. The first is OCA1a, and means that the organism cannot develop pigment at all. The hair is usually white (often translucent) and the skin very pale. Vision usually ranges from 20/200 to 20/400. The second is OCA1b, which has several subtypes itself. Some individuals with OCA1b can tan and also develop pigment in the hair. One subtype of OCA1b is called OCA1b TS (temperature sensitive), where the tyrosinase Tyrosinase Tyrosinase also known as monophenol monooxygenase is an enzyme that catalyses the oxidation of phenols and is widespread in plants and animals... can only function below a certain temperature, which causes the body hair in cooler body regions to develop pigment (i.e. get darker). (An equivalent mutation produces the coat pattern in Siamese cats Siamese (cat) The Siamese is one of the first distinctly recognized breeds of Oriental cat. The origins of the breed are unknown, but it is believed to be from Thailand. In Thailand, where they are one of several native breeds, they are called Wichian Mat... .) Another variant of OCA1b, called Albinism, yellow mutant type is more common among the Amish Amish The Amish , sometimes referred to as Amish Mennonites, are a group of Christian church fellowships that form a subgroup of the Mennonite churches... than in other populations, and results in blonde hair and the eventual development of skin pigmentation during infancy, though at birth is difficult to distinguish from other types. About 1 in 40,000 people have some form of OCA1. >- | OCA2 |
OCA2 OCA2 P protein is a protein that in humans is encoded by the OCA2 gene.OCA2 encodes the human homologue of the mouse p gene. The P protein is believed to be an integral membrane protein involved in small molecule transport, specifically tyrosine - a precursor of melanin... |
phenotype Phenotype A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior... (appearance): yellow hair, pale skin, and blue, gray or hazel eyes. About 1 in 15,000 people have OCA2. The gene MC1R doesn't cause OCA2, but does affect its presentation. >- | OCA3 |
TYRP1 TYRP1 Tyrosinase-related protein 1, also known as TYRP1, is an enzyme which in humans is encoded by the TYRP1 gene- Function :Tyrp1 is a melanocyte-specific gene product involved in melanin synthesis. Mouse Tyrp1 possesses dihydroxyindole carboxylic acid oxidase activity, The function in human... |
rufous oculocutaneous albinism (ROCA or xanthism) . The incidence rate of OCA3 is unknown. >- | OCA4 |
SLC45A2 SLC45A2 Membrane-associated transporter protein also known as solute carrier family 45 member 2 or melanoma antigen AIM1 is a protein that in humans is encoded by the SLC45A2 gene.-Function:... |
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