X-linked adrenoleukodystrophy (X-ALD): clinical presentation and guidelines for diagnosis, follow-up and management

Abstract

X-linked adrenoleukodystrophy (X-ALD) is the most common peroxisomal disorder. The disease is caused by mutations in the ABCD1 gene that encodes the peroxisomal membrane protein ALDP which is involved in the transmembrane transport of very long-chain fatty acids (VLCFA; ≥ C22). A defect in ALDP results in elevated levels of VLCFA in plasma and tissues. The clinical spectrum in males with X-ALD ranges from isolated adrenocortical insufficiency and slowly progressive myelopathy to devastating cerebral demyelination. The majority of heterozygous females will develop symptoms by the age of 60 years. In individual patients the disease course remains unpredictable. This review focuses on the diagnosis and management of patients with X-ALD and provides a guideline for clinicians that encounter patients with this highly complex disorder.

Figure 1

MRI of the brain in a case of childhood cerebral ALD showing characteristic extensive white matter changes in the parieto-occipital region and internal capsules on FLAIR sequences (A). This area is initially affected in about 80% of cases of cerebral ALD. The rim enhances after administration of gadolinium on T1 sequences (B). In about 20% of cases the site of initial involvement in cerebral ALD is the frontal white matter as shown on this FLAIR image of a different patient with cerebral ALD (C), with prominent rim enhancement after administration of gadolinium on a T1 weighted image (D).

Figure 2

MRI of the brain in a patient with AMN showing increased signal in the pyramidal tracts on T2-weighed coronal (A) and axial (B) images indicative of Wallerian degeneration.

Figure 3

MRI of the brain (T2 (A) and FLAIR (C) images; T1 with gadolinium (B, D)) of a patient with AMN who rapidly deteriorated clinically with new symptoms of cognitive decline. On MRI extensive white matter changes were seen in the parieto-occipital white matter and corpus callosum (A), but no enhancement of the lesion after administration of gadolinium (B). A follow-up MRI about 3 months later shows progression of the white matter lesion (C) and there is now faint enhancement of the rim of the lesion after gadolinium administration (D).

Figure 4

Thin and scanty scalp hair in a man with X-ALD (AMN phenotype). Written informed consent was obtained from the patient for publication of these images.

Figure 5

Flowchart describing the outpatient management of X-ALD. *If there is no gadolinium enhancement present, consider arrested cerebral ALD and repeat the MRI in 3 months.