Localization of the Aland Island eye disease locus to the pericentromeric region of the X chromosome by linkage analysis.

Aland Island eye disease (AIED) is an X-chromosomal disorder characterized by reduced visual acuity, progressive axial myopia, regular astigmatism, latent nystagmus, foveal hypoplasia, defective dark adaptation, and fundus hypopigmentation.The syndrome was originally reported in 1964 in a family on the Aland Islands.To determine the localization of the AIED gene, linkage studies were performed in this family.A total of 37 polymorphisms, covering loci on the entire X chromosome, were used.By two-point analysis the strongest evidence for linkage was obtained between AIED and DXS255 (maximum lod score [Zmax] 4.92 at maximum recombination fraction [theta max] .00).Marker loci DXS106, DXS159, and DXS1 also showed no recombination with AIED. Other positive lod scores at theta max .00 were obtained with markers localized in the XY homologous region in Xq13-q21, but the numbers of informative meioses were small.Multilocus linkage analysis indicated that the most probable location of AIED is in the pericentromeric region between DXS7 and DXS72.These results rule out localizations of AIED more distal on Xp that have been proposed by others.Our data do not exclude the possibility that AIED and incomplete congenital stationary night blindness are caused by mutations in the same gene.This question should be resolved by careful clinical comparison of the disorders and ultimately by the molecular dissection of the genes themselves.