Docosahexaenoic acid--a new therapeutic approach to peroxisomal-disorder patients: experience with two cases

Docosahexaenoic acid (DHA, 22:6 omega 3) is a major constituent of brain membrane phospholipids and photoreceptor cells. Patients with generalized peroxisomal disorders have extremely low levels of DHA in the brain and other tissues. Since a DHA deficiency could explain some basic symptoms in peroxisomal-disorder patients, we tested the possible beneficial effects of DHA in two patients with neonatal adrenoleukodystrophy (NALD). Before the treatment, both patients had very low DHA levels in plasma and erythrocytes. We first gave DHA in the form of fish oil and, in both patients, the rapid increase in red-cell DHA levels indicated that this fatty acid was being absorbed and incorporated into membrane phospholipids very fast. However, a low ratio 22:6 omega 3/22:5 omega 3 was still present in erythrocyte membranes, and the content of 20:5 omega 3 (eicosapentaenoic acid) was too high with the fish oil diet. We then began treatment with pure DHA ethyl ester and, after a few weeks, erythrocyte omega 3 polyunsaturated fatty acids were normal. There was an increase in the 18:0 molecular species of plasmalogens in both patients, most significantly in the child with affected plasmalogen biosynthesis in cultured fibroblasts. In the less severely affected NALD patient, treatment with DHA produced a very significant decrease in the ratios 24:1/22:0 and 26:1/22:0, and this child improved neurologically. The present data suggest that DHA deficiency may be the cause for some of the most characteristic abnormalities in peroxisomal-disorder patients and open new therapeutic possibilities for these patients.