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Retinal degeneration in the delayed amelanotic (DAM) chicken: an electroretinographic study.

The retinal function of the delayed amelanotic (DAM) chicken that has progressive retinal degeneration, was investigated electroretinographically (ERG). Subjects showing a gradation of abnormalities of retinal morphology and impairment of visual behaviors were tested. Dark-adapted a-, b-, and c-wave responses to full-field stimuli were studied. In general, the more severe the anatomical abnormalities, the greater the compromise of sensitivity and amplitude of ERG responses. The DAM diseases appears to affect c-waves more than a-waves, and a-waves more than b-waves. Dark-adapted responses are affected more than light-adapted responses. In DAM's with moderately to severely impaired visual behaviors, ERG studies should permit analysis of the distal retinal pathophysiology caused by this disease.

Animals↗

PubMedDate not supplied

The DAM chicken: a model for spontaneous postnatal cutaneous and ocular amelanosis.

A mutant line of chickens (DAM line) has been developed that is characterized by a high incidence of a spontaneous, postnatal, cutaneous amelanosis. Amelanotic individuals also have a high incidence of blindness and a low incidence of an integumentary defect expressed as a variable loss of feathers. A low incidence of hypothyroidism is also present but is not limited to the amelanotic phenotype. All line associated traits appear to be controlled by multiple autosomal genes. Selection experiments showed that the amelanosis and eye defect are highly heritable and partially share a common genetic basis. However, it also was shown that the incidence of blindness could be readily altered within the amelanotic population by selection. It is suggested that the blindness represents the most severe expression of the amelanosis syndrome. The amelanosis equally affected both sexes and both eumelanin and phaeomelanin pigments. A relationship was found between the presence of the back plumage color gene, E, and an increase incidence of feather amelanosis in segregating DAM line populations. This was not accompanied by an increase in blindness. The DAM line appears to be a valuable animal model for vitiligo, as well as several melanin-related eye diseases.

Albinism↗