Late-onset Zellweger spectrum disorder caused by PEX6 mutations mimicking X-linked adrenoleukodystrophy.

[x-linked adrenoleukodystrophy]

Zellweger spectrum disorder is an autosomal recessively inherited multisystem disorder caused by one of the 13 different PEX gene defects resulting in defective peroxisomal assembly and multiple peroxisomal enzyme deficiencies . We report a new patient with late-onset Zellweger spectrum disorder mimicking X-linked adrenoleukodystrophy .T his 8 .5 -year -old boy with normal development until 6 .5 years of age presented with bilateral sensorineural hearing loss during a school hearing test . He then developed acute -onset diplopia , clumsiness , and cognitive dysfunction at age 7 years . Magnetic resonance imaging of the brain revealed symmetric leukodystrophy , although without gadolinium enhancement . Elevated plasma very long chain fatty acid levels were suggestive of X-linked adrenoleukodystrophy , but his ABCD 1 gene had normal coding sequence and dosage . Additional studies of cultured skin fibroblasts were consistent with Zellweger spectrum disorder . Molecular testing identified disease-causing compound heterozygous mutations in the PEX 6 gene supporting the Zellweger spectrum disorder diagnosis in this patient .We describe a new patient with late-onset Zellweger spectrum disorder caused by PEX 6 mutations who presented with an acute neurodegenerative disease course mimicking X-linked adrenoleukodystrophy . This finding provides an additional reason that molecular confirmation is important for the genetic counseling and management of patients with a clinical and biochemical diagnosis of X-linked adrenoleukodystrophy .