GENETIC-STUDIES OF HUMAN APOLIPOPROTEINS .16. APOE POLYMORPHISM AND CHOLESTEROL LEVELS IN THE MAYANS OF THE YUCATAN PENINSULA, MEXICO
CLINICAL GENETICS
Authors: KAMBOH, MI; WEISS, KM; FERRELL, RE
Abstract
Structural variation at the APOE locus is a major determinant of interindividual differences in cholesterol levels in populations at large. We have determined APOE structural polymorphism and estimated its impact on total cholesterol in the Mayans of the Yucatan Peninsula from Mexico. A unique pattern of APOE allele frequency distribution was observed, with no example of the APOE*2 allele and a relatively low incidence (9%) of the APOE*4 allele, giving rise to the lowest average heterozygosity at the APOE locus observed to date. The reported elevating affect of the APOE*4 allele on cholesterol has been found to be absent in the Mayans; several possible explanations which may account for the absence of this affect are discussed. In addition to APOE the gene products of five other apolipoprotein loci were screened and low frequency variation, possibly due to European admixture, was observed in two systems (APOH and APOA-IV).
Evaluation of the APOH gene as a positional candidate for prcd in dogs
INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE
Authors: Gu, WK; Ray, K; Pearce-Kelling, S; Baldwin, VJ; Langston, AA; Ray, J; Ostrander, EA; Acland, GM; Aguirre, GD
Abstract
PURPOSE. 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 PI (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 bg 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 theta = 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 pl cd, the gene has been excluded as a primary candidate for prcd by linkage analysis.