Skip to main content
ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #112895
Title: IMPAIRED SYNTHESIS OF DOCOSAHEXAENOIC ACID (DHA) IN PATIENTS WITH X-LINKED RETINITIS PIGMENTOSA (XLRP)

Author
item HOFFMAN, DENNIS - RETINA FOUNDAT OF THE SW
item DEMAR, JAMES - CNRT/BAYLOR COL OF MED
item BIRCH, DAVID - RETINA FOUNDAT OF THE SW
item Heird, William
item ANDERSON, ROBERT - UNIV OF OK HLTH SCI CNTR

Submitted to: International Society for the Study of Fatty Acids and Lipids
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: To test the hypothesis that a low rate of endogenous biosynthesis of DHA contributes to low plasma and erythrocyte levels of DHA observed in patients with XLRP, a severe form of genetically inherited retinitis pigmentosa, DHA biosynthesis was measured in 5 severely visually impaired patients with XLRP and in 5 age-matched controls. Biosynthesis was determined over a period of 35d following an oral bolus of 0.5 g U-13C-AL by monitoring the accumulation in plasma of the m+18 isotopomers of DHA an other intermediates of the pathway. 13C-enrichment of the n-3 fatty acids of the plasma lipid fraction was determined by gas chromatography/mass spectrometry and the total concentration of each fatty acid was determined by flame-ionization gas chromatography. Data were expressed as total accumulation of each 13C-fatty acid (% enrichment x concentration). Mean accumulations of m+18 isotopomers of 18:3n-3, 18:4n-3, and 20:4n-3 was 46% % 26% and 49% higher, respectively, in patients with XLRP than in controls. In contrast, mean accumulation of m+18 isotopomers of 20:5n-3, 22:5n-3 and 22:6n-3 in patients with XLRP was 69%, 68% and 46%, respectively, of that in controls. Peak enrichment of 13C-DHA was observed at 240h in patients with XLRP vs. 144h in controls (p=0.04). Rate of disappearance of the m+18 isotopomers did not differ between groups. Despite interindividual variation in rates of endogenous conversion of 18:3n-3 to 22:6n-3 in both groups, these data are consistent with a lower rate of Delta5 desaturation in patients with XLRP and/or some combination of a lower rate of elongatio of 22:5n-3 to 24:5n-3, Delta6 desaturation of 24:5n-3 or beta-oxidation of 24:6n-3. We conclude that a low rate of biosynthesis of DHA contributes to lower plasma and erythrocyte DHA levels in patients with XLRP.