The fatty acid composition of various lipid fractions isolated from erythrocytes and blood plasma of patients with Duchenne and congenital myotonic muscular dystrophy.

Ten lipid fractions, both neutral and phospholipids, were isolateed from erythrocytes of patients with Duchenne and congenital myotonic dystrophy. These fractions were: phosphatidylethanolamine, phosphatidylcholine, phosphatidylserine, sphingomyelin, lysophosphatidylcholine, phosphatidic acid, glycosphingolipids, triglycerides, diglycerides and one unknown. The fatty acid compositions were compared with control values. The major deviation was a decreased level of palmitoleic acid (16 : 1omega7) in three neutral lipid fractions. It was lowered from 9.1 to 1.3% in diglycerides and from 10.6 to 2.6% in triglycerides in myotonic dystrophy. In Duchenne muscular dystrophy this percentage was decreased from 9.1 to 4.0 in diglycerides. From blood plasma were isolated phosphatidylcholine, lysophosphatidylcholine, sphingomyelin and phosphatidylethanolamine. The myristic acid (14 : 0) content was raised in lysophosphatidylcholine (from 4.4 to 8.6%) and in sphingomyelin (from 3.3 to 5.0%) in myotonic dystrophy, In the latter phospholipid the stearic acid level was decreased from 18.6 to 12.8%. In phosphatidylcholine from plasma in myotonic dystrophy the level of eicosatrienoic acid (20 : 3omega6) was lowered from 3.1 to 2.0%. Plasma fractions from Duchenne dystrophy showed no deviation. The results do not constitute an explanation for the various biochemical abnormalities found in dystrophic erythrocytes. Neither do they point to a defect in a major pathway in lipid metabolism. However, an aberration in the de novo synthesis of lipids in immature red blood cells cannot be excluded.