Atypical Neurologic Phenotype and Novel SLC30A10 Mutation in Two Brothers with Hereditary Hypermanganesemia

Manganese (Mn) is an essential element in trace quantity but large amounts are toxic. A novel hereditary disorder encompassing high blood Mn levels, dystonia, polycythemia, distinctive T1 hyperintense signals in the basal ganglia on magnetic resonance imaging (MRI) brain, and chronic liver disease was recently described. The disorder is caused by mutations in a Mn transporter encoding gene SLC30A10. We are reporting the clinical features of this rare disorder in two Saudi brothers. The older brother presented with progressive gait difficulties, hypotonia, intermittent dystonia, polycythemia, and characteristic T1-hyperintense lesions on MRI brain. SLC30A10 sequencing identified a novel missense mutation. The younger brother was identified in presymptomatic phase on family screening. Chelation therapy with disodium calcium edetate (ethylenediaminetetraacetic acid, EDTA) led to stabilization of gait, reduction in Mn levels, and resolution of polycythemia. We wish to highlight the atypical neurologic presentation, a novel missense mutation, and beneficial effect of EDTA in this rare disease.