Peroxisomal localization of the immunoreactive beta-oxidation enzymes in a neonate with a beta-oxidation defect. Pathological observations in liver, adrenal cortex and kidney.

ABSTRACT

A boy born to healthy, unrelated parents, presented at birth with hypotonia and seizures. Very long chain fatty acids in the plasma were strongly elevated; bile acid intermediates and plasmalogen biosynthesis were normal. Acyl-CoA oxidase activity was normal. The patient died at the age of 3 months. The cerebellum and medulla oblongata showed neuronal migration defects. The specific biochemical basis for the impaired peroxisomal beta-oxidation has not been found. The three immunoreactive peroxisomal beta-oxidation enzymes and catalase were localized in the hepatocellular peroxisomes. Aberrant features of the peroxisomes included a subpopulation of organelles larger than 1 micron, an amorphous nucleoid in many organelles, and invaginations of the peroxisomal membrane into the matrix. Peroxisomes in the proximal renal tubules also contained the three immunoreactive beta-oxidation enzymes. Regularly spaced trilamellar inclusions were seen in hepatic macrophages; they were much more abundant in adrenocortical macrophages. The inclusions were birefringent and resistant to acetone extraction. Distinct hepatic fibrosis had developed over a period of 2.5 months. We speculate that the impaired beta-oxidation is due to a defect at the level of the peroxisomal carnitine octanoyl or -acetyl transferase, responsible for the export of beta-oxidation products.