Albinism, Oculocutaneous, Type IV

Clinical Characteristics
Ocular Features: 

The ocular manifestations in type IV oculocutaneous albinism are similar to those of other types.  Nystagmus, strabismus, misrouting of neuronal axons, and foveal hypoplasia are prominent features although there is some clinical heterogeneity among patients.  Nystagmus may not be present at birth but is almost always evident by 3-4 months of age.  The iris may be pale blue or tan and does not generally darken with age.  Poor stereopsis is common.  Vision is stable after childhood and usually in the range of 20/100-20/400. 

Systemic Features: 

Hair color is generally intermediate between white and brown but many patients have only white hair and in others the hair is brown.  Little darkening occurs as patients become older.  The skin is often white or creamy yellow. 

Genetics

This type of oculocutaneous albinism is one of the more common types found among Japanese and maybe Chinese individuals although it has been reported in German and Turkish individuals.  This is a rare autosomal recessive form of albinism caused by mutations in the MATP (SLC45A2) gene located at 5p13.3. 

A single Japanese family with 16 affected members has been reported.  The transmission pattern was consistent with autosomal dominant inheritance with heterozygous mutations in the SLC45A22 gene segregating appropriately.

Other types include OCA1 (203100, 606952 ), OCA2 (203200 ), OAC3 (203290), OAC5 (615179), and OCA6 (113750)..

Treatment
Treatment Options: 

There is no treatment for the hypopigmentation.  Low vision aids and tinted lenses may help some patients.  Exposure to the sun should be limited. 

References
Article Title: 

Oculocutaneous albinism

Gronskov K, Ek J, Brondum-Nielsen K. Oculocutaneous albinism. Orphanet J Rare Dis. 2007 Nov 2;2:43. Review.

PubMed ID: 
17980020

References

Oki R, Yamada K, Nakano S, Kimoto K, Yamamoto K, Kondo H, Kubota T. A Japanese Family With Autosomal Dominant Oculocutaneous Albinism Type 4. Invest Ophthalmol Vis Sci. 2017 Feb 1;58(2):1008-1016.

PubMedID: 28192564

Gronskov K, Ek J, Brondum-Nielsen K. Oculocutaneous albinism. Orphanet J Rare Dis. 2007 Nov 2;2:43. Review.

PubMedID: 17980020

Inagaki K, Suzuki T, Shimizu H, Ishii N, Umezawa Y, Tada J, Kikuchi N, Takata M, Takamori K, Kishibe M, Tanaka M, Miyamura Y, Ito S, Tomita Y. Oculocutaneous albinism type 4 is one of the most common types of albinism in Japan. Am J Hum Genet. 2004 Mar;74(3):466-71.

PubMedID: 14961451

Rundshagen U, Zuhlke C, Opitz S, Schwinger E, Kasmann-Kellner B. Mutations in the MATP gene in five German patients affected by oculocutaneous albinism type 4. Hum Mutat. 2004 Feb;23(2):106-10.

PubMedID: 14722913