Oxidative stress is induced in female carriers of X-linked adrenoleukodystrophy.

X-linked adrenoleukodystrophy (X-ALD) is a peroxisomal disease biochemically characterized by the accumulation of very long chain fatty acids (VLCFA), particularly hexacosanoic (C26:0) and tetracosanoic acids (C24:0) in different tissues and in biological fluids and clinically characterized by central and peripheral demyelination and adrenal insufficiency. A considerable number of heterozygotes (HTZ) for X-ALD develop neurological symptoms like spinal cord involvement resembling milder forms of adrenomyeloneuropathy. However, the mechanisms of brain damage in hemizygotes and heterozygotes X-ALD individuals are poorly understood. Considering that oxidative stress was involved in various neurodegenerative disorders and that in a previous study we showed evidence that oxidative stress is probably involved in the pathophysiology of X-ALD symptomatic patients, in the present study we evaluated various oxidative stress parameters, namely thiobarbituric acid-reactive substances (TBA-RS), total antioxidant status (TAS) and total antioxidant reactivity (TAR) in plasma of HTZ individuals for X-ALD. It was observed that female carriers present a significant increase of TBA-RS measurement, indicating a stimulation of lipid peroxidation, as well as a decrease of TAR, reflecting a deficient capacity to rapidly handle an increase of reactive species. These results indicate that oxidative stress is involved in the pathophysiology of heterozygotes for X-ALD.

Induction of lipid peroxidation and decrease of antioxidant defenses in symptomatic and asymptomatic patients with X-linked adrenoleukodystrophy.

Patients affected by X-linked adrenoleukodystrophy (X-ALD) present a progressive brain and peripheral demyelination and adrenal cortex insufficiency, associated with accumulation of the very long chain fatty acids (VLCFA) hexacosanoic acid (C26:0) and tetracosanoic acid (C24:0) in different tissues and biological fluids. X-ALD is characterized by heterogeneous clinical phenotypes. Seven clinical variants have been described for this genetic disorder, being the childhood cerebral form (CCER), adrenomyeloneuropathy (AMN) and asymptomatic the most common clinical forms. In a previous work, we showed evidence that oxidative stress is involved in the pathophysiology of X-ALD symptomatic patients. In the present study, we compared oxidative stress parameters, namely thiobarbituric acid reactive substances (TBA-RS) and total antioxidant status (TAS), in plasma from patients with CCER, AMN and in asymptomatic X-ALD patients. It was observed that symptomatic and asymptomatic X-ALD patients presented a significant increase of plasma TBA-RS measurement, indicating a stimulation of lipid peroxidation. Furthermore, lipid peroxidation was higher in AMN, as compared to CCER and asymptomatic patients. We also observed that the total antioxidant defenses (TAS) were decreased in symptomatic but not in asymptomatic X-ALD patients. Therefore, it may be presumed that asymptomatic patients seem to be protected against oxidative stress because of their normal antioxidant defenses and that other factors besides oxidative damage may be responsible for the severity of the symptoms in X-ALD and need to be investigated.