Adult onset cerebral adrenoleukodystrophy: report of an atypical case.

X-linked adrenoleukodystrophy (X-ALD) is a rare, inherited peroxisomal disorder caused by pathogenic variants in the ABCD1 gene, which encodes an ATP-binding cassette transporter located on Xq28. These pathogenic variants result in defective peroxisomal beta-oxidation and accumulation of very long-chain fatty acids (VLCFAs) in plasma and tissues, primarily affecting the adrenal cortex, myelin in the central nervous system, and Leydig cells. The estimated incidence is approximately 1 in 17,000 individuals (Kemp et al. 2016). Clinically, X-ALD is characterized by a broad phenotypic spectrum, including three main presentations: isolated adrenocortical insufficiency, adrenomyeloneuropathy (AMN), and cerebral X-ALD (Raymond et al. 1999). Considerable clinical overlap exists among these forms, and disease severity can vary. The cerebral form most commonly presents in childhood, between ages 4 and 8, whereas adult-onset cerebral X-ALD is rare, representing only about 1% of cases (Bezman et al., American Journal of Medical Genetics. 76(5):415-419, 1998). The parieto-occipital white matter is classically involved, while predominant frontal lobe lesions are unusual. Misdiagnosis is frequent, with rates up to 31%, particularly when cognitive and behavioral changes mimic frontotemporal dementia (Jiang et al., Acta Neurologica Belgica. 123(6):2259-2268, 2023). This report describes a 53-year-old man with an atypical adult-onset cerebral X-ALD presenting with frontal lobe involvement and rapid progression. The case underscores the importance of considering X-ALD in adults presenting with atypical cognitive decline and non-classical MRI patterns.