Conditions · Metabolism: amino acids and the urea cycle
Oculocutaneous albinism !
Oculocutaneous albinism is a group of inherited conditions with little or no melanin in skin, hair and eyes, and reduced vision.
Updated 2026-11-01
Structures involved
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In biochemistry
In histology
Why it happens
What it is
Inherited failure of melanin production in melanocytes. Type 1 is due to lack of tyrosinase, the enzyme that starts melanin synthesis from tyrosine.
Who gets it
It affects 1 in 4,000 to 7,000 people in African populations and 1 in 12,000 to 15,000 in European populations; some isolated communities have more cases.
Causes
- OCA1: variants of the TYR gene (tyrosinase)
- OCA2: OCA2 gene (P protein); the most common type worldwide
- OCA3 and OCA4: TYRP1 and SLC45A2 genes
- Autosomal recessive inheritance
Risk factors
- Carrier parents
- Consanguinity
Pathophysiology
Tyrosinase turns tyrosine into DOPA and dopaquinone, the starting point of melanin. Without melanin, skin is not protected from ultraviolet light and the retina and fovea develop poorly. Optic nerve fibres cross abnormally at the chiasm, which reduces binocular vision.
Classification
- OCA1A: no tyrosinase activity, no pigment for life
- OCA1B: some activity, pigment increases with age
- OCA2, OCA3, OCA4 and other genetic types
Symptoms and signs
- Very light skin and hair
- Translucent iris
- Nystagmus
- Photophobia
- Low visual acuity and strabismus
Diagnosis
- Clinical
- Hypopigmented skin and hair with eye findings (iris transillumination, foveal hypoplasia, nystagmus).
- Tests
- Genetic testing for the type; visual evoked potentials showing the abnormal crossing at the chiasm.
- Imaging
- Optical coherence tomography shows foveal hypoplasia.
Treatment
- Conservative
- Glasses or contact lenses, low-vision aids and filters for photophobia
- Lifestyle
- Strict sun protection: clothing, hat and sunscreen
- Follow-up
- Regular skin checks by dermatology
- Surgical
- Strabismus surgery in selected cases
Complications
- Squamous and basal cell skin cancer
- Visual disability
- Social stigma
Prognosis
Life expectancy is normal if skin cancer is prevented; low vision is permanent.
Test yourself
Think of the answer, then tap the question to see it.
Which enzyme is missing in oculocutaneous albinism type 1?
Tyrosinase, which turns tyrosine into DOPA and dopaquinone, the first steps of melanin.
Why is binocular vision poor in albinism?
Lack of melanin disturbs foveal development and makes too many optic fibres cross at the chiasm.
What is the main skin risk in albinism?
Skin cancer, especially squamous cell carcinoma, from lack of protection against ultraviolet light.
Related conditions
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Oculocutaneous albinism: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026); TYR gene: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026); Tyrosine catabolism (Reactome, 2026).
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Representative model, for educational purposes only.
