Diffuse hypomyelination is not obligate for POLR3-related disorders

Roberta La Piana, Ferdy K. Cayami, Luan T. Tran, Kether Guerrero, Rosalina van Spaendonk, Katrin Õunap, Sander Pajusalu, Tobias Haack, Evangeline Wassmer, Dagmar Timmann, Hanna Mierzewska, Bwee T. Poll-Thé, Chirag Patel, Helen Cox, Tahir Atik, Huseyin Onay, Ferda Ozkınay, Adeline Vanderver, Marjo S. van der Knaap, Nicole I. WolfGeneviève Bernard

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Abstract

To report atypical MRI patterns associated with POLR3A and POLR3B mutations. This was a multicenter retrospective study to collect neuroradiologic, clinical, and molecular data of patients with mutations in POLR3A and POLR3B without the classic MRI phenotype, i.e., diffuse hypomyelination associated with relative T2 hypointensity of the ventrolateral thalamus, globus pallidus, optic radiation, corticospinal tract at the level of the internal capsule, and dentate nucleus, cerebellar atrophy, and thinning of the corpus callosum. Eight patients were identified: 6 carried mutations in POLR3A and 2 in POLR3B. We identified 2 novel MRI patterns: 4 participants presented a selective involvement of the corticospinal tracts, specifically at the level of the posterior limbs of the internal capsules; 4 patients presented moderate to severe cerebellar atrophy. Incomplete hypomyelination was observed in 5 participants. Diffuse hypomyelination is not an obligatory feature of POLR3-related disorders. Two distinct patterns, selective involvement of the corticospinal tracts and cerebellar atrophy, are added to the MRI presentation of POLR3-related disorders
Original languageEnglish
Pages (from-to)1622-1626
JournalNeurology
Volume86
Issue number17
DOIs
Publication statusPublished - 26 Apr 2016

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