Thesis

Apolipoprotein E and phytanic acid in retinitis pigmentosa

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Awarding institution
  • University of Strathclyde
Date of award
  • 1998
Thesis identifier
  • T9420
Qualification Level
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Department, School or Faculty
Abstract
  • Retinitis pigmentosa (RP) is a group of inherited progressive retinal degenerations. Various lipid abnormalities have been associated with RP. It has been demonstrated that lipids play an important function in vision. Therefore, a defect in lipid transport may lead to the retinal degeneration found in RP. Apolipoprotein E is a polymorphic protein, which has three common isoforms E2, E3 and E4. Thus, there are six different phenotypes E2/E2, E3/E2, E4/E2, E3/E3, E4/E3 and E4/E4. A ten-fold increase in the incidence of the unusual apo E2/E2 phenotype in the German RP population was reported. In addition, a fourfold increase in the E2/E2 and an eight-fold increase of E4/E4 were reported in the Scottish RP population. In this study, increased incidence of E2/E2 was not observed. However, there was an increase in the incidence of E4/E4. Some RP subjects who were suspected of having an apo E variant were investigated by cysteamine modification, SDS-PAGE and apo E DNA sequencing. However, the presence of mutations in these individuals was not confirmed. Therefore, the role of apo E in RP remains uncertain; although there is not a mutation, the dysfunctional apo E2 and E4 isoforms may contribute to the expression of the disease. Refsum’s disease is an autosomal recessive disorder associated with RP. The analysis of phytanic acid levels in two suspected RP patients confirmed the diagnosis. Since then, they have been treated with a low phytanic acid diet and their phytanic acid levels monitored during this project. The investigation of the involvement of different apo E phenotypes in the transport of phytanic acid showed that the E2/E2 RP subjects have higher phytanic acid level than those with the E3/E3 phenotype. However, recently it was demonstrated in this laboratory that normal E2/E2 people also may have high phytanic acid levels compared to normal E3/E3. This finding may indicate that E2/E2 individuals transport phytanic acid less efficiently, resulting in its accumulation in the plasma.
Advisor / supervisor
  • Converse, Carolyn A.
Resource Type
DOI
EThOS ID
  • 881915

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