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)
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)

   
 
TypeInheritance/DefectClinical
 
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