What are the other Names for this Condition? (Also known as/Synonyms)
- Albinism NOS
What is Albinism? (Definition/Background Information)
- Albinism is a group of inherited abnormalities characterized by a partial or total absence of the pigment melanin, which gives color to the eyes, hair, and skin. It is a congenital defect that causes a pale, whitish appearance of the skin, eyes, and hair, due to low or absent pigmentation
- There are 2 main types of Albinism and these include:
- Oculocutaneous Albinism (OCA): It is the most widespread type of Albinism amongst all races, with reduced or absent pigmentation in the hair, eyes and skin. OCA is subdivided into 7 forms (OCA1 to OCA7), based on the genetic mutation that causes the condition
- Ocular Albinism (OA): It is less frequent and occurs only in the eyes
- Certain medical conditions and diseases can also cause absence of pigmentation on limited to specific areas/parts of the body. This is known as localized Albinism. These conditions have their own terminology. Also, a loss of pigmentation later in life, such as in vitiligo, burns, or other conditions, are not termed Albinism
- Lack of or reduced pigmentation in the eyes, either alone, or in combination with very pale skin and hair, as well as light sensitivity of the eyes and skin, are the major symptoms of this condition. A diagnosis of Albinism is made based on the symptoms, vision exams, and genetic tests, if necessary
- Protecting the skin and eyes from sunlight and corrective surgery for vision abnormalities are the main treatment modalities considered for this disorder. Albinism is a genetic condition that cannot be prevented. However, the prognosis is excellent in most cases, and the affected individuals can lead a normal quality of life
Who gets Albinism? (Age and Sex Distribution)
- Albinism is a congenital disorder (occurring at birth), affecting both genders, all races and ethnicities. The estimated frequency is about 1 in 18,000-20,000 births
- Oculocutaneous Albinism (a type of Albinism) has been observed with a higher incidence among African-Americans
- Ocular Albinism is mostly observed in males
- Puerto Ricans exhibit a higher prevalence of Hermansky-Pudlak syndrome, a localized variant of Albinism, which is somewhat unique to this population
What are the Risk Factors for Albinism? (Predisposing Factors)
The risk factors of Albinism may include:
- A family history of the disorder
- Being of Puerto Rican, African-American, or sub-Saharan African heritage
- The male gender, since Ocular Albinism is reported predominantly in males
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 Albinism? (Etiology)
Albinism is caused by genetic mutations that affect the production and distribution of melanin in the body.
- Melanin is a naturally occurring substance that gives a distinct color (brown, black, or yellow) to the skin and hair
- The properties of melanin protect the body from skin damage, from exposure to sunlight and cancers
Albinism is classified into the following 2 major types:
- Oculocutaneous Albinism (OCA)
- Ocular Albinism (OA)
Oculocutaneous Albinism: It is the most frequent type caused by mutation(s) in 7 genes, which forms the basis of their classification into the following 7 subtypes.
- OCA1 or tyrosine-related Albinism, results from a mutation in the gene coding for the enzyme tyrosinase, which catalyzes conversion of the amino acid tyrosine to melanin. Individuals with this type of mutation may not produce any tyrosinase (termed OCA1A) or produce low amounts of the enzyme (termed OCA1B), leading to differences in the hair and skin color between these sub-forms
- OCA2 is caused by defects in the OCA2 gene coding for P protein, which facilitates tyrosinase action. Individuals with OCA2 produce melanin in reduced quantities
- OCA3, a rare disorder, develops as a result of mutation(s) in TYRP1 gene, which codes for a protein associated with tyrosinase. The pigmentation in individuals with OCA3 may not be very low
- OCA4 is caused by defects in the SLC45A2 gene. The protein coded by this gene facilitates the function of tyrosinase, and the affected individuals have decreased melanin synthesis, similar to OCA2
- OCA5 has been mapped to chromosome 4, and is a rare subtype of OCA
- OCA6 is a rare disorder, and is caused by mutations in the SLC24A5 gene
- OCA7 is also rare, and is caused by mutations in the C10orf11 gene
The OCA forms of Albinism are inherited in an autosomal recessive pattern. In this type of inheritance, an individual must possess both copies of the causative gene in the defective form in every cell of his/her body for the condition to manifest itself. An affected individual inherits one defective copy from each parent. The parents are carriers of the condition and are generally not affected.
Ocular Albinism: This form of Albinism is relatively rare, when compared to the oculocutaneous form. OA is caused by mutations in the G protein-coupled receptor 143 (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 Albinism?
The signs and symptoms of Albinism may differ among the affected individuals in type and severity. The following are some common symptoms of the condition:
- Pale white, yellow, or lighter than normal color of skin and hair
- Sometimes, patchiness on the skin may be observed
- Sensitivity of skin to light
- 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 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 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 Albinism?
The potential complications of Albinism include:
- Emotional stress
- Extreme sensitivity of eyes and skin to light
- Severe sunburns with exposure to sun
- Skin cancer
- Vision defects
- Social isolation, due to skin color change, which may affect the quality of life
How is Albinism Treated?
The treatment measures for Albinism generally focus on protecting the skin from sunburns and correcting eye abnormalities. The following are the common methods of treatment:
- For skin protection: Use of sunscreens with a high SPF (sun protection factor)
- For eye abnormalities:
- Visual aids to help low or poor vision
- Tinted glasses to reduce light sensitivity
- Use of UV-protected sunglasses
- Use of wide-brimmed hats for sunny days
A surgical correction of eye defects, such as strabismus and nystagmus, may be undertaken following evaluation by the healthcare provider.
How can Albinism be Prevented?
Currently, there are no specific methods or guidelines to prevent Albinism, since it is a genetic 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
- Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders such as Albinism
What is the Prognosis of Albinism? (Outcomes/Resolutions)
- The prognosis of Albinism is generally good, as the affected individuals are reported to have normal life expectancy
- However, due to light-sensitivity of both the eyes and skin, the choice of activities/profession may be limited, for some individuals
- There is an increased susceptibility to skin cancers and other malignant melanomas. However, with early diagnosis and prompt treatment, the outcomes can be positive
Additional and Relevant Useful Information for Albinism:
- The US FDA is currently researching drugs that have the potential to increase pigmentation of the hair and eyes, to a certain degree
- A variant of Oculocutaneous Albinism, known as Hermansky-Pudlak syndrome is caused by mutations in 9 different genes, causing 9 subtypes of the disease. Apart from the reduced/lack of pigmentation in the eyes, skin, and hair, the affected individuals also have bleeding problems and easy bruising