(OCA, acronym for Oculo-Cutaneous Albinism)

Prevalence is variable, depending on the type, but estimated at 1/20,000. Autosomal recessive transmission. Association of abnormalities of the pigmentation of the skin, dander, iris and retina due to deficiency in the tyrosinase required for the synthesis of melanin.  Normal life expectancy and  intelligence. In severe forms: white hair, pink skin, iris is either blue, yellow / orange, light brown or pink and transluscent. Eye: nystagmus, strabismus, decreased visual acuity, reduced stereoscopic vision due to a constant associated anomaly of the pathway of the optic nerve, photophobia, iris color from blue or yellow orange to light brown.

 

Four different forms:

-         type 1 [MIM 203 100] or tyrosinase negative: TYR gene mutation (11q14.2); prevalence 1/40.000; three forms:

*         classic or 'albino' or OCA1A: absence of enzymatic  activity; milky white skin, white hair, blue eyes

*        "yellow" or OCA1B [MIM 606 952]: there is still a residual activity of the enzyme during the first two decades of life: blond hair, blue or yellow-orange eyes, discreet tan

*        thermal or OCA1C: pigmentation is limited to the limbs

-         type 2 [MIM 203 200], OCA2 or tyrosinase positive form: mutations of the OCA2 gene  (15q12-q13) coding for a protein regulating the pH in the melanosomes, most frequent among the Navajo native Indians; in general there is some nascent pigmentation with blond hair and blue to light brown eyes; a similar hypomelanosis of hair and skin is sometimes found in the Angelman  and Prader-Willi syndromes (see these terms) because the causative chromosome deletion is located on 15q11-q13.

-         type 3 [MIM 203 290] or redhead or red, OCA3: mutations of the TYRP1 gene (9p23) coding for the tyrosinase-related protein 1; particularly described in South Africa and New Guinea (1/850): patients have red or mahogany hair and hazel or brown eyes

-         type 4 [MIM 606 574] OCA4: mutation of the MATP gene or SLC45A2 (5p13.2); described especially among the Japanese, yellow or blond hair and blue-grey eyes.

-        type 5 [MIM 615 312], OCA5: described in one Pakistanese family

-        type 6, OCA6 : mutation of the SLC24A5 gene (15q21.1)

-        type 7 [MIM 615 179], OCA7: mutation of the C10ORF11(LRMDA) gene (10q22.2-q22.3)

-        type 8 [MIM 619 165], OCA8: mutation of the DCT gene (13q32.1)

Visual disorders, risk of skin burns in case of sun exposure and increased risk of skin cancer. 

 Anesthetic implications: 

photophobia, protection of the skin and the eyes from dazzling light in the operating room

References : 

-        Bahadoran P, Lipsker D. 
Leucodermies. 
EMC- Dermatologie Cosmétologie 2005; 2 : 20-42.

Updated: August 2022