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DOI: 10.1055/s-0038-1672175
Juvenile Canavan Disease: A Leukodystrophy without White Matter Changes
Funding None.Publication History
21 June 2018
10 August 2018
Publication Date:
10 October 2018 (online)

Introduction
A 5-year-old boy presented with insidious onset mild motor and speech delay. He was born to unrelated healthy parents. His perinatal period was uneventful. There has no history of loss of previously attained milestones. He could ambulate without assistance and talk in small sentences of 3 to 4 words. On examination, his head circumference was 50 cm (0 to + 1 SD). He had central hypotonia and brisk deep tendon reflexes. Magnetic resonance imaging (MRI) of brain showed symmetrical T2 hyperintense caudate, putamen, and medial thalami. Magnetic resonance spectroscopy (MRS) revealed an elevated N-acetylasparlate (NAA) peak ([Fig. 1]). These clinico-radiological findings were consistent with juvenile (mild) Canavan's disease (CD). Targeted ASPA gene analysis detected a pathogenic homozygous missense variation in exon 6 of the ASPA gene (chr17:3402303; A > G; p.Tyr288Cys; ENST00000263080) confirming the diagnosis. The parents did not undergo genetic testing.


Canavan disease is a spongiform leukodystrophy caused by homozygous or compound heterozygous mutations in the ASPA gene. Classical MRI findings in CD include diffuse symmetrical white matter abnormalities, prominent early affection of subcortical U fibers, bilateral involvement of globus pallidum with sparing of caudate and putamen.[1] Anecdotal reports of atypical clinical (protracted disease course) and MRI patterns (absent white matter changes with symmetrical T2 hyperintense caudate and putamen), as seen in the index case, do exist in literature.[1] [2]
The index case reiterates the existence of a milder juvenile variant of CD with above described atypical radiological features.
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References
- 1 Van der Knaap MS, Valk J. Canavan disease. In: Magnetic Resonance of Myelination and Myelin Disorders. 3rd ed. Heidelberg/Berlin: Springer; 2005: 326-333
- 2 Yalcinkaya C, Benbir G, Salomons GS. , et al. Atypical MRI findings in Canavan disease: a patient with a mild course. Neuropediatrics 2005; 36 (05) 336-339