What are the other Names for this Condition? (Also known as/Synonyms)
- Nettleship-Falls Ocular Albinism
- Ocular Albinism Type 1
- X-Linked Ocular Albinism (XLOA)
- XLOA (X-Linked Ocular Albinism)
What is Ocular Albinism? (Definition/Background Information)
- Ocular Albinism (OA) is a rare genetic disorder, characterized by the partial or complete absence of the pigment melanin, in the eyes of the affected individuals. The reduced or absent melanin in the eyes affects vision in those with OA
- Ocular Albinism Type 1 is the most common form of the disorder. OA is predominantly reported in males, since it follows an X-linked inheritance pattern
- Having a family history of OA is a significant risk factor for being born with the disorder. Ocular Albinism is known to be caused by mutation(s) in the GPR143 gene. This gene regulates the formation of melanosomes, which are the sites of melanin synthesis
- Loss of pigmentation in the eyes, sensitivity to light, and reduced vision acuity are some common symptoms of the condition. A diagnosis of the condition is undertaken based on the presenting symptoms, vision exam, and genetic tests, if necessary
- Protecting the eyes from sunlight and corrective surgery for vision defects are the main treatment modalities considered for this disorder. Ocular Albinism is a genetic condition, and is therefore, not preventable. However, the prognosis is good in most cases, and the affected individuals can lead a normal quality of life
Who gets Ocular Albinism? (Age and Sex Distribution)
- Ocular Albinism is rare, affecting approximately 1 in 20,000 to 1 in 60,000 individuals
- The disorder predominantly affects males
- Individuals belonging to all races and ethnic groups are susceptible to OA
What are the Risk Factors for Ocular Albinism? (Predisposing Factors)
The following are some known risk factors for Ocular Albinism (OA):
- Family history of OA
- Male gender
It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.
Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.
What are the Causes of Ocular Albinism? (Etiology)
Ocular Albinism is caused by mutations in the G protein-coupled receptor 143 or GPR143 gene.
- Under normal circumstances, the GPR143 gene codes for a protein in the retina and skin cells. This protein plays a crucial role in the development of pigmentation in the eyes by regulating the formation of melanosomes. These structures are the seats of melanin synthesis and storage
- When the gene is mutated, the resultant protein has an aberrant structure or size. This interferes with the function of the protein, such that proper growth and maturation of the melanin-producing structures do not take place
- Additionally, the melanin in retinal cells also plays a significant role in normal vision. Therefore, individuals with the ocular type of albinism also present with various problems with their vision
This disorder is predominantly reported in males, since it is inherited in an X-linked manner. In this type of inheritance, the defective gene is carried on the X chromosome. Females have two X chromosomes, and the unaffected gene copy masks the effects of a defective gene copy. However, since males have only one X chromosome inherited from their mother, the defective gene is expressed in them, causing the disorder.
What are the Signs and Symptoms of Ocular Albinism?
The signs and symptoms of Ocular Albinism may differ among affected individuals in type and severity. In most affected individuals, the hair and skin color are normal, although some may present with a lighter shade of skin and/or hair color when compared to unaffected family members.
The following are some common symptoms of the condition:
- Pale blue, red, or purple iris (eye)
- Decreased vision/visual clarity
- Blurred vision
- Sensitivity of eyes to light
- Nystagmus - an irregular and continuous eye movement
- Astigmatism - formation of distorted images in the retina
- Strabismus - crossed eyes
- Macular hypoplasia – improper development of the macula, which is a part of retina involved in vision clarity
How is Ocular Albinism Diagnosed?
The diagnosis of Albinism is made by the following tests and exams:
- A thorough physical examination and assessment of symptoms
- An evaluation of family medical history
- Examination of the eyes for structural abnormalities
- Vision exam
- Visual-evoked potential (VEP) testing in children with visual problems
- Genetic testing for checking causative gene mutations in the fetus, if a family history of Ocular Albinism is present
Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.
What are the possible Complications of Ocular Albinism?
The potential complications from Ocular Albinism include:
- Extreme sensitivity of eyes to light
- Vision problems
- Social isolation, which may affect the quality of life
How is Ocular Albinism Treated?
Ocular Albinism is treated in the following ways:
- Use of visual aids to help low or poor vision
- Tinted glasses to reduce light-sensitivity
- Use of UV-protected sunglasses
- Use of wide-brimmed hats to protect eyes from sensitivity to light
- Surgical correction for conditions such as strabismus and nystagmus
How can Ocular Albinism be Prevented?
- Ocular Albinism is a genetic disorder, and no specific methods or guidelines exist to prevent the condition
- Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
- If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
- Annual eye checkup and vision exams are highly recommended to prevent the development of complications
Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders such as Ocular Albinism.
What is the Prognosis of Ocular Albinism? (Outcomes/Resolutions)
- The prognosis of Ocular Albinism is good, as life expectancy is typically not affected
- However, due to light-sensitivity of the eyes, the choice of activities/profession for some individuals may be limited
- Regular eye examinations and vision acuity tests can help minimize complications
Additional and Relevant Useful Information for Ocular Albinism:
The US FDA is currently researching drugs that have the potential to increase pigmentation of hair and eyes, to a certain degree.