Canine CNGB3 mutations establish cone degeneration as orthologous to the human achromatopsia locus ACHM3.
Cone degeneration (cd ) is an autosomal recessive canine disease that occurs naturally in the Alaskan Malamute and German Shorthaired Pointer breeds. It is phenotypically similar to human achromatopsia, a heterogeneous autosomal recessive disorder associated with three distinct loci. Both the canine disease and its human counterparts are characterized by day-blindness and absence of retinal cone function in adults. We report linkage of the canine cd locus to marker C29.002 on canine chromosome 29 at recombination fraction theta = 0.0 with a maximum LOD score of 24.68 in a series of informative outbred pedigrees derived from cd-affected Alaskan Malamutes. Conserved gene order between CFA29 and the long arm of human chromosome 8 argued for homology between the cd locus and the human achromatopsia locus, ACHM3, at 8q21-22. The canine homolog of the cyclic nucleotide-gated channel beta-subunit gene (CNGB3), responsible for the human ACHM3 disease phenotype, was mapped within the zero-recombination interval for the cd locus. A deletion removing all exons of canine CNGB3 was identified in cd-affected Alaskan Malamute-derived dogs. A missense mutation in exon 6 (D262N, nucleotide 784) within a conserved region of the same gene was detected in German Shorthaired Pointers affected with an allelic disorder. Identification of these canine disorders as homologs of human ACHM3 underscores the power of recent developments in canine genomics, and provides a valuable system for exploring disease mechanisms and evaluating potential therapeutic measures in disorders of cone photoreceptors.
Center for Canine Genetics and Reproduction, James A. Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Duska J
DJ
Sidjanin
Jennifer K
JK
Lowe
John L
JL
McElwee
Bruce S
BS
Milne
Taryn M
TM
Phippen
David R
DR
Sargan
Gustavo D
GD
Aguirre
Gregory M
GM
Acland
Elaine A
EA
Ostrander
D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D003117:Color Vision Defects / Q000235:genetics*; D054815:Cyclic Nucleotide-Gated Cation Channels; D004247:DNA / Q000235:genetics; D004283:Dog Diseases / Q000235:genetics*; D004285:Dogs; D005260:Female; D008040:Genetic Linkage; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007473:Ion Channels; D008297:Male; D009154:Mutation; D010375:Pedigree; D010786:Photoreceptor Cells / Q000378:metabolism*; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism*; D012164:Retinal Diseases / Q000235:genetics / Q000662:veterinary*; D013045:Species Specificity
C415904:CNGB3 protein, human; D054815:Cyclic Nucleotide-Gated Cation Channels; D007473:Ion Channels; D004247:DNA