Polyunsaturated fatty acid lipidosis. II. Lipid biochemical studies.

Lipid analyses were performed on cerebral tissue from three children who had died of a progressive encephalopathy and from one living child in an early stage of the disease. In the terminal stage of the disease, the cortex and white matter content of all lipid classes, particularly the sphingolipids, were very low. The concentration of gangliosides of the cerebral cortex was 10%, and of cerebrosides in white matter, 2-3% of the normal values for the age. The porportion of the minor gangliosides with short carbohydrate chains was increased because the reduction affected mainly the four major brain gangliosides GM1, GD1a, GD1b and GT1. In the child from whom the biopsy specimen was obtained in an early phase of the disease the cerebral lipid pattern appeared to be normal. A patient who had died of neuronal ceroid-lipofuscinosis (Janský-Bielschowsky) did not show any major lipid changes. The fatty acid patterns of the phosphoglycerides showed such changes as have never been observed in any other disease. In the three advanced cases the fatty acid compositions in cerebral cortex and white matter were identical. In ethanolamine phosphoglycerides the proportions of 18: 1 and 20: 4 (n-6) were increased, while those of 22: 4 (n-6) and 22: 6 (n-3) were markedly diminished. Similar changes in the fatty acid patterns were found in the other phosphoglycerides. In the early phase of the disease 22: 4 (n-6) was decreased and 18: 1 increased. We propose that this new disease be termed polyunsaturated fatty acid lipidosis (PFAL).