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Åland Islands eye disease
An X-linked recessive retinal disease characterized by fundus hypopigmentation, decrased visual acuity, nystagmus, astigmatism, progressive axial myopia, defective dark adaptation and protanopia.
ORPHA:178333Classification level: Disorder
AIED is a very rare disease originally reported in a family from Aland islands in the Bothnia sea. Some other cases from the Baltic area and other origins have been reported but the clinical features of these cases overlap with X-linked incomplete congenital stationary night blindness (CSNB2; see this term).
AIED is characterized by hypopigmented eye fundus, foveal dysplasia with no foveal reflex that leads to decreased visual acuity, progressive axial myopia, latent nystagmus, astigmatism, night blindness and protan color vision defect. The hypopigmentation is most pronounced in the posterior pole and in the peripapillary region. Female carriers may show slight disturbances of color discrimination and subtle nystagmus.
AIED is caused by mutations in the CACNA1F gene. Some mutations in CACNAF1 are associated with CSNB2 suggesting allelism of the two disorders.
Patients with a clinical suspicion of AIED should undergo a complete ophthalmologic examination including funduscopy, visual acuity, refraction defects, electroretinogramm (ERG) and color vision test. Mutation screening of CACNA1F gene including the presence of large deletions in the gene can help the clinical diagnosis.
Differential diagnosis includes X-linked ocular albinism (OA1; see this term) and CSNB2. The lack of misrouting of optic nerve axons excludes OA1 whereas CSNB2 is apparently stationary with a normal fovea and, usually, no color defects.
AIED is an X-linked disorder, with a carrier female having a 50% risk of transmitting the mutation to her offspring. Carrier testing for at-risk female relatives is possible. Genetic counseling of the family is recommended.
Management and treatment
No treatment is available except for correction of the myopia.
Except for progression of axial myopia, the disease presents a stationary course.
A summary on this disease is available in Deutsch (2011) Español (2011) Français (2011) Italiano (2011) Nederlands (2011) Português (2011) Greek (2011, pdf)