The effect of 4:1 glyceryl trioleate-glyceryl trierucate (Lorenzo’s oil) on disease progression in 89 asymptomatic boys (mean age 4.7+/-4.1 years; range 0.2-15 years) with X-linked adrenoleukodystrophy (ALD) and normal brain MRI was studied at Johns Hopkins University, Baltimore, MD, and other centers. Therapy was initiated before 7 years of age in 64 patients. Sixty-six patients (74%) had no neurologic deterioration at a mean follow-up of 6.9 years, 21 (24%) developed MRI abnormalities, and 8 (9%) had both neurologic and MRI abnormalities. Those with neurologic abnormalities had the childhood cerebral phenotype. Boys with an elevated plasma hexacosanoic acid had a significantly increased risk of more rapid progression and MRI abnormalities. Lowering of the hexacosanoic acid plasma level following treatment with Lorenzo’s oil (LO) was associated with a reduced risk of developing MRI abnormalities. LO therapy is recommended in asymptomatic patients with X-linked ALD and normal MRI. 
COMMENT. Lorenzo’s oil therapy is recommended in boys, especially those <7 years of age, with ALD who are asymptomatic, have normal MRI, and are at risk of developing the childhood cerebral form of ALD. The authors stress that this recommendation is based on suggestive, not definitive, evidence of a preventive effect. Potential patients are identified by assays of very long-chain fatty acids in at-risk relatives of patients with known ALD or idiopathic Addison’s disease.