Albinism

A group of inherited genetic disorders characterized by reduced or absent melanin production due to defects in melanocyte function or melanin synthesis, despite a normal number of melanocytes.

Epidemiology

  • Prevalence: approximately 1 in 17,000–20,000 worldwide
  • Occurs in all ethnic groups
  • Usually present from birth
  • Most forms are autosomal recessive

Aetiology

Albinism results from mutations affecting melanin biosynthesis or melanosome function, including:
  • TYR (tyrosinase) – OCA type 1
  • P protein defect — OCA type 2
  • TYRP1 – OCA type 3
  • SLC45A2 – OCA type 4

Pathophysiology

  • Melanocytes are present in normal numbers
  • Defective conversion of tyrosine → DOPA → melanin
  • Leads to hypopigmentation of skin, hair, and eyes

Clinical presentation

Classification

Oculocutaneous Albinism (OCA)
Involves skin, hair, and eyes.
Type
Defect
Key Features
OCA1
Tyrosinase deficiency
Severe, little/no pigment
OCA2
P protein
Partial pigmentation
OCA3
TYRP1
Reddish-brown pigment
OCA4
SLC45A2
Similar to OCA2
Ocular Albinism
  • Mainly affects the eyes
  • X-linked (GPR143 mutation)
  • Minimal skin involvement

Clinical Features

Cutaneous
  • Generalized hypopigmentation from birth
  • White to light-yellow hair
  • Very fair skin
  • Inability to tan
notion image
Ocular (Hallmark)
  • Nystagmus
  • Photophobia
  • Reduced visual acuity
  • Strabismus
  • Foveal hypoplasia
  • Translucent iris

Investigations

Test
Purpose
Ophthalmologic exam
Visual abnormalities
Hair bulb test
Reduced tyrosinase activity
Genetic testing
Confirm subtype

Management

No curative treatment

Supportive Care

  • Strict photoprotection
  • Sunscreens (SPF ≥30)
  • Protective clothing
  • Regular skin cancer screening

Ophthalmologic Care

  • Corrective lenses
  • Visual aids
  • Early intervention for amblyopia