Multimodal imaging of a patient with RAB39B mutation.

Mutations in RAB39B gene have been linked to intellectual deficiency associated with parkinsonism, also referred as to Waisman syndrome. As it appears to be a very rare cause of Parkinson Disease (PD), with only few cases described in the literature, the typical clinical and radiological features are yet to be determined. In this article, we report and illustrate multimodal brain imaging by computed tomography, magnetic resonance imaging, transcranial ultrasound (US), dopamine transporter single photon emission computed tomography and [18F]-fluorodeoxyglucose positron emission tomography ([18F]FDG-PET) in a 37-year-old man with PD features and mild mental retardation harboring a new RAB39B mutation. We then propose a comparison with data previously published regarding neuroimaging in this condition and present a summary of previous imaging reports. If our patient's results partly support previously described radiological features, they also highlight potential new characteristics of this rare syndrome. To the best of our knowledge, [18F]FDG-PET and transcranial US have never been reported before in this condition. This is therefore the first multimodal brain imaging description of a patient presenting RAB39B mutation.