Adrenomyodystrophy

Adrenomyodystrophy, also known as adrenomyeloneuropathy (AMN), is a form of X-linked adrenoleukodystrophy (X-ALD) caused by mutations in the ABCD1 gene located on chromosome Xq28. This gene encodes a peroxisomal membrane transporter protein involved in the breakdown of very long-chain fatty acids (VLCFAs). When this protein is dysfunctional, VLCFAs accumulate in tissues throughout the body, particularly affecting the adrenal glands, spinal cord, and peripheral nerves. Adrenomyodystrophy is considered the adult-onset form of X-ALD and typically manifests in young adult males, usually between the ages of 20 and 40 years. The condition primarily affects the nervous system and the adrenal glands. Key clinical features include progressive spastic paraparesis (stiffness and weakness of the legs), peripheral neuropathy, bladder and bowel dysfunction, sexual dysfunction, and adrenal insufficiency (Addison disease). Patients often experience difficulty walking that worsens over time, sensory changes in the lower extremities, and impaired balance. Adrenal insufficiency may precede neurological symptoms by years or decades and can present with fatigue, weight loss, skin hyperpigmentation, and potentially life-threatening adrenal crises. Some patients may also develop cerebral demyelination, which can lead to cognitive decline and more rapid neurological deterioration. Diagnosis is confirmed by elevated plasma VLCFA levels and molecular genetic testing of the ABCD1 gene. Treatment is primarily supportive and includes adrenal hormone replacement therapy (corticosteroids and sometimes mineralocorticoids) for adrenal insufficiency, physical therapy, antispasticity medications, and management of bladder dysfunction. Hematopoietic stem cell transplantation (HSCT) and gene therapy have shown benefit in the cerebral form of X-ALD but are not standard treatments for the isolated myeloneuropathy of AMN. Lorenzo's oil and dietary VLCFA restriction have been investigated but have not demonstrated clear clinical benefit in halting neurological progression. Ongoing research continues to explore disease-modifying therapies for this condition.

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