Ocular albinism OA , which is much less common, involves only the eyes, while skin and hair may appear similar or slightly lighter than that of other family members. Over the years, researchers have used various systems for classifying oculocutaneous albinism. In general, these systems contrasted types of albinism having almost no pigmentation with types having slight pigmentation. In types with slight pigmentation, hair appears more yellow or has a reddish tinge and vision may be better. DNA tests can determine the precise type of albinism.
Research on albinism genes is ongoing. Some are further divided into subtypes. This enzyme helps the body to change the amino acid, tyrosine, into pigment. There are two subtypes of OCA1. In OCA1A, the enzyme is inactive and no melanin is produced, leading to white hair and very light skin. People with OCA2 make a minimal amount of melanin pigment and can have hair color ranging from very light blond to brown. People with OCA3 can have substantial pigment.
They have reported mutations on three additional causative genes. As gene testing becomes available, and more people with these types of albinism are identified, the complete range of physical manifestations will be recognized, and may overlap with other known types of OCA.
Currently, these types of albinism are considered to be uncommon. Researchers have also identified several other genes that result in albinism with other features. In addition to albinism, HPS is associated with bleeding problems and bruising. Some forms are also associated with lung and bowel disease.
HPS is a less common form of albinism but should be suspected if a person with albinism shows unusual bruising or bleeding or if a genetic test for a type of OCA produces inconclusive results. Autosomes are the 22 pairs of chromosomes that contain genes for our general body characteristics, compared to the one pair of sex chromosomes. We normally have two copies of these chromosomes and the many genes on them — one inherited from our father, the other inherited from our mother.
That means that most types of albinism result from inheriting an albinism trait from both the mother and the father who often have typical pigmentation. In this case, the mother and father are considered to be carriers of the albinism trait because they each carry a recessive gene for the condition but do not manifest the condition themselves.
When both parents carry the albinism gene and neither parent has albinism there is a one in four chance at each pregnancy that the baby will be born with albinism.
Ocular albinism OA1 is caused by a change in the GPR gene that plays a signaling role that is especially important to pigmentation in the eye. OA1 follows a simpler pattern of inheritance because the gene for OA1 is on the X chromosome. Females have two copies of the X chromosome while males have only one copy and a Y chromosome that makes them male. Griscelli syndrome usually results in death within the first decade of life. The most accurate way to diagnose albinism is through genetic testing to detect defective genes related to albinism.
Less accurate ways of detecting albinism include an evaluation of symptoms by a doctor or an electroretinogram test. This test measures the response of the light-sensitive cells in the eyes to reveal eye problems associated with albinism. Results from a small clinical trial 5 people suggest that the drug nitisinone can help increase melanin in the skin and hair of people with OCA1b. More research is needed. Hermansky-Pudlak syndrome, Chediak-Higashi syndrome, and Griscelli syndrome do affect life expectancy.
This is because of the health problems associated with the syndromes. These syndromes are all very rare. People with albinism may have to limit their outdoor activities because their skin and eyes are sensitive to the sun. UV rays from the sun can cause skin cancer and vision loss in some people with albinism.
White hair is characteristic of aging, but colorless hair strands can appear at any age — even while you're still in high school or college.
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Understanding Albinism. Carriers do not have albinism but can pass on the gene. Some types of OA are passed on in an X-linked inheritance pattern.
This pattern affects boys and girls differently: girls who get the albinism gene become carriers, while boys who get it will have albinism. When a mother is a carrier of an X-linked type of albinism, each of her daughters has a 1 in 2 chance of becoming a carrier.
Each of her sons has a 1 in 2 chance of having albinism. When a father has an X-linked type of albinism, his daughters will become carriers, and his sons will not have albinism and will not be carriers. If you have a history of albinism in your family or you have a child with the condition, you may want to talk to a GP about getting a referral for genetic counselling. A genetic counsellor provides information, support and advice about genetic conditions.
For example, you can discuss with them how you inherited albinism and the chances of passing it on. Albinism is usually obvious from a baby's appearance when they're born. Your baby's hair, skin and eyes may be examined to look for signs of missing pigment.
As albinism can cause a number of eye problems, your baby may be referred to an eye specialist ophthalmologist for tests. Electrodiagnostic testing is also sometimes used to help diagnose albinism. This is where small electrodes are stuck to the scalp to test the connections of the eyes to the part of the brain that controls vision.
Although there's no cure for the eye problems caused by albinism, there are a number of treatments, such as glasses and contact lenses, that can improve vision. As a child with albinism gets older, they'll need regular eye tests , and it's likely they'll need to wear glasses or contact lenses to correct vision problems. Sunglasses, tinted glasses and wearing a wide-brimmed hat outside can help with sensitivity to light. There's currently no cure for nystagmus where the eyes move from side to side involuntarily.
However, it is not painful and does not get worse. Certain toys or games may help a child make the most of the vision they have. An ophthalmologist will be able to provide further advice. Surgery, involving dividing and then reattaching some of the eye muscles, may sometimes be an option. The main treatments for squints are glasses, eye exercises, surgery and injections into the eye muscles.
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