title: Evaluation of the APOH gene as a positional candidate for prcd in dogs.
abstract: OBJECTIVE
  Progressive rod-cone degeneration (prcd) is an autosomal recessive retinal degeneration of dogs characterized by abnormalities in lipid metabolism. It has recently been mapped to the centromeric region of canine chromosome 9, homologous to human 17q, which contains the apolipoprotein H (apoH, protein; APOH, gene) gene involved in lipid metabolism and regulation of triglycerides. The present study was undertaken to evaluate APOH as a positional candidate for prcd.
  
  
  METHODS
  Expression of APOH in the retina was examined by reverse transcription-polymerase chain reaction (RT-PCR) and by immunocytochemistry in normal and prcd-affected dogs. The level of apoH in the plasma was determined by western blot analysis. Intragenic polymorphic markers were identified and typed in the prcd pedigree. Canine-rodent hybrid cell lines were analyzed to detect canine APOH.
  
  
  RESULTS
  ApoH has been localized to the photoreceptor outer segment layer by immunocytochemistry. Its expression in the retina of normal and prcd-affected dogs was confirmed by RT-PCR. The levels of antihuman apoH cross-reacting material in plasma were similar in all dogs, regardless of disease status. Finally, linkage analysis of the APOH gene with the disease locus in the prcd pedigree detected 3 recombinants among 70 informative offsprings (lod score 15.09 at 0 = 4.3 centimorgan [cM]).
  
  
  CONCLUSIONS
  APOH is expressed in the retina and tightly linked to the prcd locus. However, despite its potential role in phenotypes of abnormal lipid metabolism associated with prcd, the gene has been excluded as a primary candidate for prcd by linkage analysis.
authors.affiliation: James A. Baker Institute, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853-6401, USA.
authors.forename: W
authors.initials: W
authors.lastname: Gu
authors.forename: K
authors.initials: K
authors.lastname: Ray
authors.forename: S
authors.initials: S
authors.lastname: Pearce-Kelling
authors.forename: V J
authors.initials: VJ
authors.lastname: Baldwin
authors.forename: A A
authors.initials: AA
authors.lastname: Langston
authors.forename: J
authors.initials: J
authors.lastname: Ray
authors.forename: E A
authors.initials: EA
authors.lastname: Ostrander
authors.forename: G M
authors.initials: GM
authors.lastname: Acland
authors.forename: G D
authors.initials: GD
authors.lastname: Aguirre
mesh_terms: D000818:Animals; D001483:Base Sequence / Q000235:genetics; D015153:Blotting, Western; D002460:Cell Line; D002874:Chromosome Mapping; D004283:Dog Diseases / Q000235:genetics* / Q000378:metabolism; D004285:Dogs; D015870:Gene Expression / Q000502:physiology; D008040:Genetic Linkage / Q000235:genetics; D006023:Glycoproteins / Q000235:genetics* / Q000378:metabolism; D006822:Hybrid Cells; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D010375:Pedigree; D011110:Polymorphism, Genetic / Q000235:genetics; D012160:Retina / Q000378:metabolism; D012162:Retinal Degeneration / Q000235:genetics / Q000378:metabolism / Q000662:veterinary*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012377:Rodentia; D053482:beta 2-Glycoprotein I
chemical_list: D006023:Glycoproteins; D053482:beta 2-Glycoprotein I