Impaired degradation of phytanic acid in cells from patients with mitochondriopathies: evidence for the involvement of ETF and the respiratory chain in phytanic acid alpha-oxidation.

Phytanic acid alpha-oxidation was studied in cultures of skin fibroblasts and myoblasts from patients with various defects of the respiratory chain in order to obtain information on the subcellular site and the mechanism of this pathway. In fibroblasts from patients with complex IV (cytochrome c oxidase) deficiency or glutaricaciduria type II, phytanic acid alpha-oxidation was reduced to 14% of normal, whereas in myoblasts from patients with complex I (NADH-Q reductase) deficiency, it was normal. Apparently, at least one step of phytanic acid alpha-oxidation occurs in mitochondria and in this process electrons are transferred to the respiratory chain via the electron-transfer flavoprotein (ETF).