X-linked Adrenoleukodystrophy

Clinical Case: X-linked Adrenoleukodystrophy in a 7-Year-Old Boy

Patient Presentation

A 7-year-old boy named Ethan presents to the pediatric clinic with his parents. They report a progressive decline in his school performance over the past 6 months. His teacher noticed increasing inattention and difficulty comprehending instructions. His parents also express concerns about his deteriorating handwriting skills and frequent falls while playing.

History

Previously healthy with a normal birth and developmental history. Ethan's parents have noticed that he has become progressively more withdrawn and irritable. His sleep patterns are disrupted, often waking up in the middle of the night.

Family history reveals that a maternal uncle had a “neurological illness” in his childhood and died in his teens. No further details are available.

Physical Examination

Ethan appears anxious. His neurological exam reveals:

• Hyperreflexia in both the upper and lower limbs
• Positive Babinski sign on the left
• Mild spasticity in the legs
• Impaired tandem walking and frequent falls
• Visual and auditory examinations are normal

Investigations

1. MRI of the brain: Shows bilateral, symmetrical, high-intensity signals in the parieto-occipital white matter, suggestive of demyelination.
2. Blood tests: Revealed elevated very long-chain fatty acids (VLCFA) levels.
3. Genetic testing: Confirmed a mutation in the ABCD1 gene.

Diagnosis

Based on the clinical findings, imaging results, elevated VLCFA levels, and genetic testing, Ethan was diagnosed with X-linked adrenoleukodystrophy (X-ALD).

Discussion

X-ALD is a peroxisomal disorder caused by mutations in the ABCD1 gene, leading to the accumulation of VLCFA in tissues. This accumulation damages the myelin sheath of neurons and the adrenal cortex.

X-ALD has various phenotypes:

1. Childhood Cerebral Form: As seen in Ethan, symptoms typically begin between ages 4-10. It's characterized by progressive neurologic decline with behavioral changes, vision loss, hearing deficits, and motor dysfunction.
2. Adrenomyeloneuropathy (AMN): Presents in late 20s to early 30s with progressive paraparesis, sphincter disturbances, and adrenocortical insufficiency.
3. Addison-only phenotype: Presents with adrenal insufficiency without neurologic symptoms.

Management and Prognosis

Early diagnosis is crucial. Hematopoietic stem cell transplantation can arrest the progression if done in the early stages. Adrenal insufficiency, if present, requires lifelong glucocorticoid replacement.

Ethan's parents were counseled about the disease, and a multidisciplinary approach involving neurologists, endocrinologists, and physiotherapists was initiated for his care. Genetic counseling was also provided to the family.

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