Increase in central striatal dopamine transporters in patients with Shwachman-Diamond syndrome: additional evidence of a brain phenotype.

Patients with Shwachman-Diamond syndrome (SDS) do not only experience well-described physical features like skeletal abnormalities and hematological dysfunctions, but recent studies also suggested attention and working memory deficits in SDS. Indeed, a recent structural magnetic resonance imaging (MRI) study demonstrated smaller brain regions in SDS. Regarding attention and working memory, however, an important role for the neurotransmitter dopamine is well established. Therefore, in this study we assessed in vivo dopamine transporters (DATs; a specific marker of dopaminergic cells expressed in nerve terminals) and performed structural MRI in SDS. In 6 and 5 young SDS patients, respectively, we were able to acquire DAT single photon emission computed tomography (SPECT) and MRI examinations, and the data were compared to age-matched control data. Striatal DAT binding was significantly increased in SDS patients as compared to controls. In addition, we observed significantly smaller volumes particularly posteriorly and caudally located in the brain: the corpus callosum, brainstem, and cerebellum. Also the thalamus was smaller in SDS patients than in controls. In conclusion, our data replicate earlier findings on smaller brain regions in SDS. In addition, our novel molecular imaging data suggest that SDS patients may have a dysregulated dopaminergic system. These findings may be of relevance to increase our understanding of behavioral and cognitive deficits in SDS.