Roberta La Piana1, Ferdy K Cayami1, Luan T Tran1, Kether Guerrero1, Rosalina van Spaendonk1, Katrin Õunap1, Sander Pajusalu1, Tobias Haack1, Evangeline Wassmer1, Dagmar Timmann1, Hanna Mierzewska1, Bwee T Poll-Thé1, Chirag Patel1, Helen Cox1, Tahir Atik1, Huseyin Onay1, Ferda Ozkınay1, Adeline Vanderver1, Marjo S van der Knaap1, Nicole I Wolf1, Geneviève Bernard2. 1. From the Laboratory of Neurogenetics of Motion (R.L.P.) and Department of Neuroradiology (R.L.P.), Montreal Neurological Institute and Hospital, and the Departments of Neurology and Neurosurgery (R.L.P., L.T.T., K.G., G.B.) and Pediatrics (R.L.P., L.T.T., K.G., G.B.), McGill University, Montreal, Canada; Departments of Child Neurology (F.K.C., M.S.v.d.K., N.I.W.) and Clinical Genetics (F.K.C., R.v.S.), VU University Medical Center, Amsterdam, the Netherlands; Department of Genetics (K.Õ.) United Laboratories, Tartu University Hospital, Tartu; Department of Pediatrics (K.Õ.), University of Tartu, Estonia; Institute of Human Genetics (T.H.), Technische Universität München; Institute of Human Genetics (T.H.), Helmholtz Zentrum München, Munich, Germany; Department of Neurology (E.W.), Birmingham Children's Hospital, UK; Department of Neurology (D.T.), University Clinic Essen, University of Duisburg-Essen, Germany; Department of Child and Adolescent Neurology (H.M.), Institute of Mother and Child, Warsaw, Poland; Department of Child Neurology (B.T.P.), AMC Academic Medical Center, Amsterdam, the Netherlands; West Midlands Regional Clinical Genetics Unit (C.P., H.C.), Birmingham Women's Hospital, UK; Departments of Pediatrics (T.A.) and Medical Genetics (H.O.), Faculty of Medicine (F.O.), Ege University, Izmir, Turkey; Department of Neurology (A.V.), Children's National Health System, Washington, DC; Neuroscience Campus Amsterdam (M.S.v.d.K., N.I.W.), the Netherlands; and Department of Medical Genetics (G.B.), Montreal Children's Hospital, McGill University Health Center, Montreal, Canada. 2. From the Laboratory of Neurogenetics of Motion (R.L.P.) and Department of Neuroradiology (R.L.P.), Montreal Neurological Institute and Hospital, and the Departments of Neurology and Neurosurgery (R.L.P., L.T.T., K.G., G.B.) and Pediatrics (R.L.P., L.T.T., K.G., G.B.), McGill University, Montreal, Canada; Departments of Child Neurology (F.K.C., M.S.v.d.K., N.I.W.) and Clinical Genetics (F.K.C., R.v.S.), VU University Medical Center, Amsterdam, the Netherlands; Department of Genetics (K.Õ.) United Laboratories, Tartu University Hospital, Tartu; Department of Pediatrics (K.Õ.), University of Tartu, Estonia; Institute of Human Genetics (T.H.), Technische Universität München; Institute of Human Genetics (T.H.), Helmholtz Zentrum München, Munich, Germany; Department of Neurology (E.W.), Birmingham Children's Hospital, UK; Department of Neurology (D.T.), University Clinic Essen, University of Duisburg-Essen, Germany; Department of Child and Adolescent Neurology (H.M.), Institute of Mother and Child, Warsaw, Poland; Department of Child Neurology (B.T.P.), AMC Academic Medical Center, Amsterdam, the Netherlands; West Midlands Regional Clinical Genetics Unit (C.P., H.C.), Birmingham Women's Hospital, UK; Departments of Pediatrics (T.A.) and Medical Genetics (H.O.), Faculty of Medicine (F.O.), Ege University, Izmir, Turkey; Department of Neurology (A.V.), Children's National Health System, Washington, DC; Neuroscience Campus Amsterdam (M.S.v.d.K., N.I.W.), the Netherlands; and Department of Medical Genetics (G.B.), Montreal Children's Hospital, McGill University Health Center, Montreal, Canada. genevieve.bernard@mcgill.ca.
Abstract
OBJECTIVE: To report atypical MRI patterns associated with POLR3A and POLR3B mutations. METHODS: 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. RESULTS: 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. CONCLUSION: 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.
OBJECTIVE: To report atypical MRI patterns associated with POLR3A and POLR3B mutations. METHODS: 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. RESULTS: 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. CONCLUSION: 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.
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Authors: Mary R Richards; Lacey Plummer; Yee-Ming Chan; Margaret F Lippincott; Richard Quinton; Philip Kumanov; Stephanie B Seminara Journal: J Med Genet Date: 2016-08-10 Impact factor: 6.318
Authors: Karine Choquet; Sharon Yang; Robyn D Moir; Diane Forget; Roxanne Larivière; Annie Bouchard; Christian Poitras; Nicolas Sgarioto; Marie-Josée Dicaire; Forough Noohi; Timothy E Kennedy; Joseph Rochford; Geneviève Bernard; Martin Teichmann; Benoit Coulombe; Ian M Willis; Claudia L Kleinman; Bernard Brais Journal: Mol Brain Date: 2017-04-13 Impact factor: 4.041