Genetic, ophthalmic, morphometric and histopathological analysis of the Retinopathy Globe Enlarged (rge) chicken.
OBJECTIVE
To identify the locus responsible for rge (retinopathy globe enlarged) in chickens and further characterise the rge phenotype.


METHODS
A colony of chickens carrying the rge mutation was rederived from a single heterozygous animal of the original line. The eyes of blind, heterozygous and normal birds were subjected to ophthalmic, morphometric and histopathological examination to confirm and extend published observations. DNA samples were obtained and subjected to a whole genome linkage search.


RESULTS
From 138 classified backcross progeny, 56 birds were blind and 82 sighted. Heterozygous birds were indistinguishable from wild type, but homozygotes had sluggish or unresponsive pupils, posterior sub-capsular lens opacities and an atrophic pecten. The fundus appeared normal with no significant pigmentary disturbance, but axial length and eye weight were increased. Pathology revealed focal retinal lesions. Linkage analysis placed the rge locus in a small region of chicken chromosome 1.


CONCLUSIONS
rge is a severe recessive retinal dystrophy in chickens, with associated globe enlargement. Linkage mapping has highlighted chicken chromosome 1 in a region most probably homologous to human chromosomes 7q31-35, 21q21 or 22q12-21. Candidate disease loci include RP10 (IMPDH1) and uncharacterised Ushers (USH1E) and glaucoma (GLC1F) loci.
Inglehearn
Chris F
CF
Molecular Medicine Unit, St. James's University Hospital, University of Leeds, Leeds, UK.
Morrice
David R
DR
Lester
Douglas H
DH
Robertson
Graeme W
GW
Mohamed
Moin D
MD
Simmons
Ian
I
Downey
Louise M
LM
Thaung
Caroline
C
Bridges
Leslie R
LR
Paton
Ian R
IR
Smith
Jacqueline
J
Petersen-Jones
Simon
S
Hocking
Paul M
PM
Burt
David W
DW
D000818:Animals; D001766:Blindness / Q000235:genetics / Q000473:pathology / Q000662:veterinary*; D002386:Cataract / Q000235:genetics / Q000473:pathology / Q000662:veterinary; D002645:Chickens / Q000235:genetics*; D002874:Chromosome Mapping; D002875:Chromosomes / Q000235:genetics; D004247:DNA / Q000032:analysis; D004195:Disease Models, Animal; D005260:Female; D005808:Genes, Recessive; D008040:Genetic Linkage; D005838:Genotype; D006984:Hypertrophy; D007908:Lens, Crystalline / Q000473:pathology; D008297:Male; D009154:Mutation; D009915:Orbit / Q000473:pathology*; D011201:Poultry Diseases / Q000235:genetics* / Q000473:pathology*; D011681:Pupil Disorders / Q000235:genetics / Q000473:pathology / Q000662:veterinary; D012162:Retinal Degeneration / Q000235:genetics / Q000473:pathology / Q000662:veterinary*
D004247:DNA