Table of Contents

Main Features
Eye Findings
Etiology
Other Findings
References

Albinism

Main Features

Oculocutaneous Albinism (OCA): Hypopigmentation of skin and hair with characteristic eye findings
Ocular Albinism (OA): Normal skin and hair pigmentation with characteristic eye findings

Eye Findings

Refractive error: significant myopia, hyperopia and/or astigmatism
Motility: Nystagmus, esotropia
Vision: Variable 20/40-20/200
Iris: Transillumination defects (from complete lack of pigmentation in OCA1 to variable small defects in OA)
Fundus: Hypopigmentation, foveal hypoplasia
Optic nerve function: Abnormal visual evoked potentials (representing abnormally high amount of decussation of ganglion cell fibers)

Etiology

OCA: autosomal recessive
- OCA1A (commonly recognized type) occurs in 1/40,000 with 1/100 are carriers
  - Two TYR gene mutations (11q14-q21) causing no tyrosinase to be produced; no melanin
- OCA1B: Two TYR gene mutations causing at least one copy of a partially active tyrosinase enzyme: less melanin
- OCA2: P gene mutation (15q11.2-q12) hair pigmented but not skin, some iris pigment
- OCA3: TYRP1 gene mutation (9p23) described in those of african descent
- OCA4: MAPT gene mutation (SLC45A2)
- Hermansky-Pudlak syndrome: mutation in any of HPS1 (10q23.1), HPS2 (5q13) , HPS3 (3q24), HPS4 (22q11.2-q12.2), HPS5-9
- Chediak-Higashi syndrome: chromosome 1
OA: Ocular Albinism
- OA1 gene mutations (Xp22): males with normal hair and skin pigment, abnormal melanosome production
  - giant melanosomes on skin biopsy if preformed, defect is in melanosome production
  - can have late onset sensorineural deafness
  - female carriers have mosaic pigmentation of peripheral fundus
- OA2: Families from Aland Islands in the Sea of Bothnia, female carriers do not have a mosaic pattern, possibly a type of CSNB (310500), (Xp11.4-p11.23) OMIM: 300600,
- OA3: Autosomal recessive. OMIM reference (6q13-q15) or (15q11.2-q12)
- OA with sensorineural deafness: OMIM reference (11q14-q21, 3p14.1-p12.3)
  - Waardenberg Syndrome type II with ocular albinism, mutation in the transcription factor MITF which regulates the TYR gene

Other Findings

OCA1A: No pigment of hair or skin, coarse rough skin, unpigmented nevi, solar keratoses (premalignant) basal cell or squamous cell carcinomas (actually quite rare due to good prevention), skin melanocytes are present but melanoma rare
OCA1B: white to very light hair and skin at birth with variable amounts of darkening, pigmented nevi and freckles can develop
OCA2: Pigmented hair at birth, no generalized skin pigmentation but pigmented nevi and freckles can develop
OCA4: Variable pigmentation of skin and hair, similar to OCA2
Hermansky-Pudlak syndrome
- Potentially lethal subtype
- Bleeding diathesis
- Pulmonary Fibrosis
- Granulomatous colitis
Chediak-Higashi syndrome
- Potentially lethal subtype
- Congenital Immunodeficiency causing infections of skin and respiratory tract
- Bleeding Diathesis
- Progressive Neurodegeneration

References

Duane's Ophthalmology: An Overview of Albinism and Its Visual System Manifestations by ELIAS I. TRABOULSI and W. RICHARD GREEN. 2006
Creel DJ, Summers CG, King RA. Visual anomalies associated with albinism. Ophthalmic Paediatr Genet 11:193-200,1990
OCA1 GeneReview
OCA2 GeneReview
OCA4 GeneReview
X-linked OA GeneReview

syndrome, albinism