We report a Japanese family with adrenoleukodystrophy (ALD) with a three base pair deletion (delGAG291) in the ALD gene. A variety of phenotypes were observed within this family. While the proband (patient 1) was classified as having a rare intermediate type of adult cerebral and cerebello-brain stem forms, his younger brother (patient 2) and nephew (patient 3) had a childhood ALD type. Another nephew (patient 4) of patient 1 was classified as having an adolescent form. The tau level in the cerebrospinal fluid (CSF) in patient 1 was as high as that of patients with Alzheimer's disease (AD). His brain magnetic resonance image (MRI) showed abnormalities in the bilateral cerebellar hemispheres and brain stem, but not in the cerebral white matter, where marked reductions of the cerebral blood flow and oxygen metabolism were clearly demonstrated by positron emission tomography (PET). In patients 2 and 3, the autopsy findings showed massive demyelination of the cerebral white matter with sparing of the U-fibers, compatible with the findings of childhood ALD. Oleic and erucic acids (Lorenzo's Oil) were administered to patients 1 and 4, but sufficient effectiveness was not obtained. The findings in this family suggest that delGAG291 is part of the cause of Japanese ALD with phenotypic variations. Moreover, although the scale of the study is limited, there is a possibility that PET can detect an insidious lesion which is undetectable by computed tomogram (CT) or MRI analysis, and that the higher level of tau reflects the process of neuronal degeneration in ALD. Lorenzo's Oil should be given in the early stage. (C) 1998 Elsevier Science B.V. All rights reserved.