In this case, the patient had known L-2-Hydroxyglutaric aciduria prior to imaging. His parents are first-degree cousins, and this is consistent with the autosomal recessive inheritance. Definitive diagnosis was previously performed by identifying L-2-Hydroxyglutaric aciduria in urine, where it is usually massive raised. However, MRI has characteristic findings and can often enable diagnosis prior to biochemical investigations. The signal changes start multi-focally in the U-fibers before progressing to confluency. This centripetal pattern of involvement is seen in only a few other leukodystrophies (Canavan and Kearns-Sayre syndrome), and the further lack of involvement of the brainstem helps to narrow the differential to L-2-Hydroxyglutaric aciduria .
In our case, the patient still has reasonable function at age 16, being self-ambulatory with mild learning difficulties. This is typical of L-2-Hydroxyglutaric aciduria, where the onset is insiduous, progression is slow and patients mostly survive into adulthood. This is in contrast to the more fulminant course of other leukodystrophies.