The patient is a 6-year-old boy, the first child of unrelated parents. He was born at 40 weeks gestation by spontaneous delivery. There were no perinatal complications. Physical examination revealed 66 increased pigmentation of the lips, tongue and buccal mucosa. Early neurological symptoms were behavioral disturbances, deterioration of vision and impaired auditory discrimination. Our patient had the following biochemical abnormalities: low morning plasma cortisol level 1.0 µg/dL (reference range 5-20 µg/ dL) and an elevated ACTH level of 62.4 ng/L (reference range 9-52 ng/L), respectively. A 1 µg-short synacthen test showed a peak cortisol response of 6.1 µg/dL (reference range 5-20 µg/ dL), confirming the primary adrenal cortex failure. Fasting plasma VLCFA levels of C22:0, C24:0 and C26:0 were 18.0 (control 22.5 ± 8.0), 39.8 (control 21.6 ± 8.0) and 1.5 µg/mL (control 0.35 ± 0.08), respectively. Ratios of C24/C22 and C26/C22 were significantly elevated at 2.21 (normal 0.74-1.627) and 0.083 (normal 0.014-0.063). Cerebral MRI typically showed extensive demyelination in the occipital periventricular white matter.