9 month old child was brought with a history of developmental delay (both motor and speech delay) and seizures. The symptoms were progressively worsening. There was no family history of similar illness. On examination, the child had large head (macrocephaly) and spasticity of all 4 limbs.
MRI brain showed megalencephalic appearance with symmetric increased signal (hyperintense) lesions on T2W and decreased signal (hypointense) lesions on T1 W images. The lesions were involving bilateral subcortical U-fibres. Thalamus, caudate nucleus, globus pallidus, putamen, corpus callosum and cerebellum were spared. The MRI findings were suggestive of Canavan’s disease.
Canavan’s disease is a rare genetic (autosomal recessive) disease (affecting 1 in 100,000 children), which occurs due to a mutation in chromosome 17, leading to a deficiency of N-acetylaspartoacylase, a key enzyme in myelin synthesis, leading to an accumulation of N-acetylaspartate (NAA) in the brain, CSF, plasma and urine.