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Tyrosinase (oculocutaneous albinism IA) (TYR)

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The TYR gene provides instructions for making an enzyme called tyrosinase. This enzyme is located in melanocytes, which are specialized cells that produce a pigment called melanin. Melanin is the substance that gives skin, hair, and eyes their color. Melanin is also found in the light-sensitive tissue at the back of the eye (the retina), where it plays a role in normal vision.

Tyrosinase is responsible for the first step in melanin production. It converts a protein building block (amino acid) called tyrosine to another compound called dopaquinone. A series of additional chemical reactions convert dopaquinone to melanin in the skin, hair follicles, the colored part of the eye (the iris), and the retina.


Contents

What is the official name of the TYR gene?

The official name of this gene is “tyrosinase (oculocutaneous albinism IA).”

TYR is the gene's official symbol. The TYR gene is also known by other names, listed below.

How are changes in the TYR gene related to health conditions?

Oculocutaneous albinism - caused by mutations in the TYR gene

More than 100 mutations in the TYR gene have been identified in people with oculocutaneous albinism type 1. These mutations disrupt the normal production of melanin, which reduces coloring of the hair, skin, and eyes and causes problems with vision. Most TYR mutations eliminate the activity of tyrosinase, preventing melanocytes from producing any melanin throughout life. These mutations cause a form of oculocutaneous albinism called type 1A (OCA1A). People with this form of albinism have white hair, light-colored eyes, and very pale skin that does not tan. Other mutations in the TYR gene reduce but do not eliminate tyrosinase activity. These mutations, which allow some melanin to be produced, cause oculocutaneous albinism type 1B (OCA1B). People with type 1B are also born with white hair, light-colored eyes, and pale skin, but hair and eye color often darken over time and skin may tan.

Where is the TYR gene located?

Cytogenetic Location: 11q14-q21

Molecular Location on chromosome 11: base pairs 88,550,687 to 88,668,473

Image:tyr.jpeg

The TYR gene is located on the long (q) arm of chromosome 11 between positions 14 and 21.

More precisely, the TYR gene is located from base pair 88,550,687 to base pair 88,668,473 on chromosome 11.

What other names do people use for the TYR gene or gene products?

  • LB24-AB
  • Monophenol monooxygenase
  • OCA1A
  • OCAIA
  • SK29-AB
  • Tumor Rejection Antigen AB
  • TYRO_HUMAN
  • tyrosinase

What glossary definitions help with understanding TYR?

acids ; albinism ; amino acid ; antigens ; cell ; compound ; enzyme ; gene ; hair follicle ; melanin ; melanocytes ; melanosome ; mutation ; pigment ; protein ; retina ; tissue ; tumor ; Tyr ; tyrosine

External Links

Where can I find additional information about TYR?

See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/​handbook/​howgeneswork/​genelocation) in the Handbook.

You and your healthcare professional may find the following resources about TYR helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

References

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