Disorders of pigmentation | Figure 2.25 A: Oculocutaneous albinism (Courtesy of Dr. Paul Getz) B: Hypomelanosis of Ito C: Incontinentia pigmenti (Reprint from Burgdorf WH, Plewig G, Wolff HH, Landthaler M, eds. Braun- Falco’s Dermatology. 3rd ed. Heidelberg: Springer; 2009) |
Oculocutaneous Albinism (OCA) (Figure 2.25A)
| | | | | Type | | Inheritance/Defect | | Clinical | | OCA, Type 1a (Tyrosinase-negative) | | AR TYR (Tyrosinase enzyme deficiency) | | No melanin in skin/hair/ eyes, white hair (over time may turn slightly yellow), milky white-pink skin, blue-gray eyes, amelanotic nevi (pink), extreme UV sensitivity, ↑ skin CA, nystagmus, strabismus, ↓ visual acuity | | OCA, Type 1b (Yellow mutant) | | AR TYR | | ↓ Tyrosinase activity, little or no pigment at birth, develop some pigment over time, milder eye findings | | OCA, Type 2 (Tyrosinase-positive) | | AR P gene (↓ Eumelanin synthesis) | | Most common OCA, broad clinical phenotype (minimal to moderate dilution), pigmented nevi develop over time, light brown hair/skin | | OCA, Type 3 (Rufous) | | AR TYRP-1 (Tyrosinase-related protein 1) | | Light brown hair/skin, blue or brown irides, nystagmus, ↓ visual acuity |
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