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Reader response: Teaching NeuroImages: A rare case of Jacobsen syndrome with global diffuse hypomyelination of brain

With interest we read the report by Patel et al.1 concerning a patient with Jacobsen syndrome due to an 11q23–11q24 deletion and MRI evidence for leukodystrophy with improvement at a follow-up, substantiated by FLAIR images. The authors claimed that these abnormalities represent hypomyelination. Hypomyelination is defined as a significant and permanent myelin deficit.2 Its MRI appearance is characterized by a diffusely hyperintense T2 white matter (WM) signal, which is less high than the signal in other leukodystrophies2,3 and certainly less high than the WM signal in the patient discussed here,1 who has strongly T2-hyperintense WM signal abnormalities.