questions 0

Albinism

Author:
Topic updated on 09/10/17 7:28pm

Snapshot
  • A 5-year-old girl presents to her primary care physician's office for counseling. She was recently diagnosed with type 2 oculocutaneous albinism based on genetic studies and clinical exam. While her skin is not completely white, it is pink and her hair is light-colored. She is counseled about wearing sunscreen, sunglasses, and sun protective clothes whenever she could be exposed to the sun, due to the increased risk of skin cancer.
Introduction
  • Clinical definition
    • hereditary defect in pigmentation
    • two most common types of albinism affecting the skin (oculocutaneous albinism)
      • type 1, known as tyrosinase-negative albinism
        • caused by mutations in tyrosinase gene
        • ↓ or complete inability to produce melanin          
      • type 2, known as tyrosinase-positive albinism
        • the most common type in the world
        • defect in tyrosinase transporter
        • ↓ melanin in skin
        • less severe than type 1       
    • other variants include ocular albinism, which affects only the eyes
  • Pathogenesis
    • normal number of melanocytes
    • ↓ production of melanin
    • ↓ tyrosinase activity or defective tyrosine transport
      • recall that melanin is formed from tyrosine
  • Genetics
    • inheritance pattern
      • autosomal recessive
    • mutations
      • type 1
        • chromosome 11
        • gene encoding tyrosinase
      • type 2
        • chromosome 15
        • OCA2 gene
        • encodes small molecule transporters involved in transport of tyrosinase
  • Associated conditions
    • skin cancer
  • Prognosis
    • patients generally live normal lives but are at increased risk for skin cancer
Presentation
  • Symptoms
    • may have ocular symptoms, such as photophobia or blurry vision
  • Physical exam
    • type 1 (more severe)
      • skin
        • white hair without any pigment
        • white or pink skin color
        • blue eyes
        • pink-red nevi
        • solar keratosis
      • ocular
        • impaired visual acuity
        • nystagmus
        • strabismus
    • type 2 (less severe)
      • pink to cream skin color
      • yellow/brown hair (not white hair)
      • blue to yellow/brown irides
      • pigmented nevi
      • freckles
Studies
  • Labs
    • genetic testing to confirm diagnosis
Differential
  •  Vitiligo
Treatment
  • Conservative
    • sunscreen, sunglasses, and avoid sun exposure
      • indication
        • for all patients in an attempt to prevent skin cancers or skin burns
  • Operative
    • vision correction surgery
      • may be indicated in cases of severe nystagmus
Complications
  • Skin cancer
  • Severe sunburns


  RATE CONTENT
5.0
AVERAGE 5.0 of 1 RATINGS

Qbank (0 Questions)



Evidence & References Show References




Topic Comments

Subscribe status: