Diagnosis of X-adrenoleucodystrophy phenotypic variants.

We report the radiological and biochemical data of a familial X-adrenoleucodystrophy with an extreme phenotypic variability, in which the diagnosis of several affected members was delayed for several years. The propositus developed a progressive dementia, while two of his brothers were diagnosed of primary Addison's disease several years previously. MRI in two cases with different phenotypes revealed hyperintense diffuse white matter lesions, and the diagnosis was confirmed by increased serum levels of very long chain fatty acids. We conclude that X-adrenoleucodystrophy should be included in the differential diagnosis of adult Addison's disease even though no neurological involvement or family history is recorded, and that MRI is a useful tool for diagnosis and follow-up of neurological involvement in this disease.