Polyunsaturated fatty acid changes suggesting a new enzymatic defect in Zellweger syndrome

The fatty acid composition of red blood cells, fibroblasts, forebrain, liver and kidney were studied in a 3-month-old infant who died from Zellweger Syndrome, and the results were compared with those of age-matched controls. Besides a typical increase in the very long chain fatty acids 26:0 and 26:1 and a great reduction in the plasmalogen levels, confirming the diagnosis of Zellweger Syndrome, some striking changes in the polyunsaturated fatty acid patterns were discovered. The most important was a very drastic decrease in the values of 22:6 omega 3 and 22:5 omega 6, the two products of delta 4-desaturation. In the kidney, the level of 22:6 omega 3 fell below that of 26:0. Consequently, the ratio 26:0/22:6 omega 3 (and 26:1/22:6 omega 3) was most useful in emphasizing the fatty acid anomalies, especially in renal tissue, where the 26:0/22:6 omega 3 ratio increased to almost 200 times the normal values. Other significant, although less consistent fatty acid alterations were increases in 18:2 omega 6, 18:3 omega 6, 20:3 omega 6, 18:4 omega 3 and 20:4 omega 3, and a decrease in 20:4 omega 6 in some tissues. The existence is proposed of a new enzyme defect in peroxisomal disorders, involving the desaturase system of long chain polyunsaturated fatty acids.