Contributor: Gordon K. Klintworth
Forsius-Eriksson albinism (Åland Island eye disease, Forsius-Eriksson disease, ocular albinism type II, Forsius-Eriksson syndrome) was originally reported in 1964 in a family on the Åland Islands. This X-linked recessive inherited condition is typified by hypopigmentation of the fundus (less severe than in ocular albinism type I [albinism - ocular type I ), diminished visual acuity, progressive axial myopia [myopia - axial], astigmatism, nystagmus, hypoplasia of the fovea [hypoplasia - fovea], defective dark adaptation, and protanomalous red-green color blindness [color blindness - protanomalous red-green]. The disorder was regarded as a type of ocular albinism, but the skin melanocytes are normal. Also, in contrast to ocular albinism type I female heterozygotes do not manifest mosaic retinal patterns, but have a latent nystagmus and mild defects in color discrimination. Futhermore in contradistinction to other forms of ocular albinism and oculocutaneous albinism there is no misrouting of the optic pathway, and the opticokinetic nystagmus does not resemble that of most albinos. The ocular abnormalities in this x-linked disorder are probably due to a high grade axial myopia with stretching of the retinal pigment epithelium. Åland Island eye disease differs from congenital stationary night blindness with myopia [night blindness with mypoia] in that the scotopic functions are only moderately affected and the peripheral photopic visual fields are not restricted. However, congenital stationary night blindness and Åland Island eye disease may be caused by mutations in the same gene. Linkage studies indicate that the location of the responsible gene is probably in the pericentromeric region of the long arm of the X-chromosome (Xq13-q21). An individual with Åland Island eye disease has also expressed a contiguous gene syndrome with features of congenital adrenal hypoplasia [hypoplasia - adrenal], glycerol kinase deficiency, and Duchenne muscular dystrophy. This deletion has been mapped to the Xp21.3-21.2 portion of the X-chromosome.