Clinical, molecular, and PET study of a case of aceruloplasminaemia presenting with focal cranial dyskinesia

Abstract

Aceruloplasminaemia is a rare recessive disorder caused by mutations in the gene encoding the multicopper ferroxidase ceruloplasmin, thought to be involved in cellular iron export. Primary intracellular iron accumulation characterises this disorder. We investigated a case of aceruloplasminaemia early in the course of the disease by structural and functional neuroimaging and correlated the results with the clinical findings. The patient, a diabetic 59 year old lady, presented with perioral dyskinesia. Magnetic resonance imaging (MRI) revealed massive iron accumulation in the basal ganglia, notably sparing the pallidum, and along the cortical surface. However, most of these structures had preserved metabolic activity as evaluated by fluorodeoxyglucose positron emission tomography (FDG-PET). Voxel based analysis of FDG-PET data showed a significant hypometabolism only in the heads of the caudate nuclei. Molecular genetic analysis revealed compound heterozygosity for two null mutations in the ceruloplasmin gene, a rather surprising finding for a very rare recessive disease, suggesting that aceruloplasminaemia could be somewhat more frequent than is commonly thought and could therefore be underdiagnosed.