Human Albinism: Recent Advances in Neurology and Motility

Abstract

The term albinism encompasses a large group of heritable disorders of pigmentation. Initially most interest was centered on the clinical hypopigmentation of eyes alone (ocular albinism) or of eyes, skin and hair (oculocutaneous albinism). In recent years, 10 forms of oculocutaneous albinism and four types of ocular albinism have been described, each of which is delineated by clinical, genetic and laboratory criteria.

Major recent advances in this subject include the separation of oculocutaneous albinism into two separate forms on the basis of hair bulb incubation in L-tyrosine, the recognition of macromelanosomes in skin and uvea in X-linked ocular albinos and their carrier mothers and the description of autosomal recessive ocular albinism.

From the viewpoint of workers in the field of ocular motility, the most significant advance is in the discovery of the anomalous retinocortical projections in all albinos. In these individuals, the line of demarcation for decussation does not fall through the macula but instead is sited approximately 20 degrees temporally on the retina. This increase in the number of fibers crossing at the chiasm may be the result of decreased pigment in the developing optic cup and in turn, may be related to the genesis of albino oculomotor anomalies.

• albinism
• strabismus
• stereopsis