AP4 deficiency: A novel form of neurodegeneration with brain iron accumulation?

Agathe Roubertie, Nelson Hieu, Charles-Joris Roux, Nicolas Leboucq, Gael Manes, Majida Charif, Bernard Echenne, Cyril Goizet, Claire Guissart, Pierre Meyer, Cecilia Marelli, François Rivier, Lydie Burglen, Rita Horvath, Christian P. Hamel, Guy Lenaers
Neurol Genet. 2018-01-24; 4(1): e217
DOI: 10.1212/nxg.0000000000000217

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ObjectiveTo describe the clinico-radiological phenotype of 3 patients harboring a homozygous novel AP4M1 pathogenic mutation.MethodsThe 3 patients from an inbred family who exhibited early-onset developmental delay, tetraparesis, juvenile motor function deterioration, and intellectual deficiency were investigated by magnetic brain imaging using T1-weighted, T2-weighted, T2*-weighted, fluid-attenuated inversion recovery, susceptibility weighted imaging (SWI) sequences. Whole-exome sequencing was performed on the 3 patients.ResultsIn the 3 patients, brain imaging identified the same pattern of bilateral SWI hyposignal of the globus pallidus, concordant with iron accumulation. A novel homozygous nonsense mutation was identified in AP4M1, segregating with the disease and leading to truncation of half of the adap domain of the protein.ConclusionsOur results suggest that AP4M1 represents a new candidate gene that should be considered in the neurodegeneration with brain iron accumulation (NBIA) spectrum of disorders and highlight the intersections between hereditary spastic paraplegia and NBIA clinical presentations.

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