Inherited retinal degeneration and ocular amelanosis in the domestic chicken (Gallus domesticus)

An inherited retinopathy in commercial breeding chickens

“…Although this sex-linked recessive condition is more obviously progressive and culminates in blindness, morphological abnormalities are present in early life which are distinctly focal and dysplastic in nature: at locations adjacent to the pecten there is thinning or absence of the retinal pigment epithelium, joss of photoreceptors and thinning and disorganisation of the outer nuclear layer. Loss of vision encountered in the delayed amelanotic (DAM) strain of chicken (Smyth et al, 1981;Fite et al, 1982;Fulton et al, 1983) is progressive and results from retinal degeneration associated with loss of choroidal melanocytes; there appears to be a strong immunogenic component and histologically the disease differs from that described here.…”

“…These three diseases all exhibit simple recessive inheritance. A further progressive form of blindness, apparently with polygenic inheritance, is encountered in the delayed amelanotic (DAM) strain of chicken where it is associated with progressive loss of somatic (including choroidal) pigment (Smyth et al, 1981;Fite et al, 1982;Fulton era/., 1983).…”

The chick eye in vision research: An excellent model for the study of ocular disease

“…This strain exhibits marked loss of melanin in its feathers and develops blindness within two weeks of the appearance of amelanotic feathers. Histopathologic analysis initially demonstrates the destruction of choroidal melanocytes and inflammatory cell infiltration in the choroid (Fite et al, 1982–1983). As vision deteriorates, choroidal involvement is followed by depigmentation of retinal pigment epithelium (RPE), loss of apical processes in the RPE, and subsequent photoreceptor cell death (Fite et al, 1982–1983, 1983; Smyth et al, 1981).…”

“…Histopathologic analysis initially demonstrates the destruction of choroidal melanocytes and inflammatory cell infiltration in the choroid (Fite et al, 1982–1983). As vision deteriorates, choroidal involvement is followed by depigmentation of retinal pigment epithelium (RPE), loss of apical processes in the RPE, and subsequent photoreceptor cell death (Fite et al, 1982–1983, 1983; Smyth et al, 1981). Evidence suggests that impaired phagocytosis in the RPE may be responsible for the retinal degeneration that occurs in the DAM strain (Lahiri and Bailey, 1993).…”

“…Fulton et al (1983) used ERG to describe variability in the visual sensitivity of DAM mutants that correlated directly with the degree of histopathological disease involvement. This mutant strain has been suggested as a model for further study of several inherited diseases involving ocular pigmentation, including vitiligo, Vogt-Koyanagi-Harada disease, Chediak-Higashi syndrome, and sympathetic ophthalmia (Fite et al, 1982–1983). …”