Amanda Cozzens
amc13@wildcats.unh.edu
University of New Hampshire Manchester

Abstract

There are many different genes which cause different types of albinism. This research was done to find out which organism (of the ones tested) has an OCA2 gene nucleotide sequence most closely related to humans. MEGA was used to analyze the nucleotide sequences and make phylogenetic trees to show the relationship between organisms. The OCA2 nucleotide sequence for the Sumatran orangutan was most closely related to a human’s sequence. By using STRING, it was found that the OCA2 protein interacts with 10 other proteins. Protein Data Bank was also used to gain a better understanding of the protein structure.


Background Information

Albinism is a group of genetic disorders which impairs the amount of melanin produced in the skin, hair, and eyes. Most people with albinism have very light skin and hair, and have light blue eyes. This genetic disorder occurs in all racial/ ethnic groups throughout the world.

albinism2.jpg
Oculocutaneous Albinism shown in a boy of black ethnicity. Image available from Google public domain.


Skin color is determined by three different pigments:
-Melanin (Yellow to black pigment, produced in the epidermis, genetically determined, can change in response to UV exposure)
-Carotene (Yellow to orange pigment, must obtain from diet, stored in fat layers)
-Hemoglobin (Reddish molecule in blood cells which circulates through capillaries, can vary over minutes)

Melanin is produced by the melanocytes in our skin. The more melanin a melanocyte produces, the darker the skin color. A main function of melanin is that it reduces the UV-induced DNA damage in skin and eyes, therefore, if there is less melanin, there is an increased risk of sun damage to the skin which could lead to skin cancer. The melanocytes for our skin and hair are called cutaneous melanocytes, while the melanocytes for our eyes are called extracutaneous melanocytes. In Albinism, there is either no melanin production, or very little, giving a very fair complexion.
melanocyte.jpg
The "starfish" shaped cell, located in the stratum basale layer of the epidermis, is the melanocyte, and the small dark dots are the melanin. Image available from Google public domain.


There are two main types of albinism:
  1. Oculocutaneous albinism (OCA): affects the melanin/ pigment production in the skin, hair, and eyes.
  2. Ocular albinism (OA): mainly affects the eyes causing visual problems, however, could have a very slight affect on the skin and hair.

Main known genes associated with each type of albinism:
-Oculocutaneous Albinism
  • TYR
  • OCA2
  • TYRP1
  • SLC45A2
-Ocular Albinism
  • GPR143

Research Questions
  1. Is Oculocutaneous Albinism more common, or do we just notice it more because it involves hypopigmented skin?
  2. When looking at nucleotide and protein sequences, which organism is most closely related to humans?


Primary Research
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