POLR3A variants with striatal involvement and extrapyramidal movement disorder

Inga Harting, Murtadha Al-Saady, Ingeborg Kraegeloh-Mann, Annette Bley, Maja Hempel, Tatjana Bierhals, Stephanie Karch, Ute Moog, Genevieve Bernard, Richard Huntsman, Rosalina M. L. van Spaendonk, Maaike Vreeburg, Agusti Rodriguez-Palmero, Aurora Pujol, Marjo S. van der Knaap, Petra J. W. Pouwels, Nicole I. Wolf*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Biallelic variants in POLR3A cause 4H leukodystrophy, characterized by hypomyelination in combination with cerebellar and pyramidal signs and variable non-neurological manifestations. Basal ganglia are spared in 4H leukodystrophy, and dystonia is not prominent. Three patients with variants in POLR3A, an atypical presentation with dystonia, and MR involvement of putamen and caudate nucleus (striatum) and red nucleus have previously been reported. Genetic, clinical findings and 18 MRI scans from nine patients with homozygous or compound heterozygous POLR3A variants and predominant striatal changes were retrospectively reviewed in order to characterize the striatal variant of POLR3A-associated disease. Prominent extrapyramidal involvement was the predominant clinical sign in all patients. The three youngest children were severely affected with muscle hypotonia, impaired head control, and choreic movements. Presentation of the six older patients was milder. Two brothers diagnosed with juvenile parkinsonism were homozygous for the c.1771-6C > G variant in POLR3A; the other seven either carried c.1771-6C > G (n = 1) or c.1771-7C > G (n = 7) together with another variant (missense, synonymous, or intronic). Striatal T2-hyperintensity and atrophy together with involvement of the superior cerebellar peduncles were characteristic. Additional MRI findings were involvement of dentate nuclei, hila, or peridentate white matter (3, 6, and 4/9), inferior cerebellar peduncles (6/9), red nuclei (2/9), and abnormal myelination of pyramidal and visual tracts (6/9) but no frank hypomyelination. Clinical and MRI findings in patients with a striatal variant of POLR3A-related disease are distinct from 4H leukodystrophy and associated with one of two intronic variants, c.1771-6C > G or c.1771-7C > G, in combination with another POLR3A variant.

Original languageEnglish
Pages (from-to)121-133
Number of pages13
JournalNeurogenetics
Volume21
Issue number2
DOIs
Publication statusPublished - Apr 2020

Keywords

  • POLR3A
  • MRI
  • Basal ganglia
  • Striatum
  • Superior cerebellar peduncle
  • Inferior cerebellar peduncle
  • Brainstem
  • Hypomyelination
  • 4H LEUKODYSTROPHY
  • POLR3-RELATED LEUKODYSTROPHY
  • DIFFUSE HYPOMYELINATION
  • RECESSIVE MUTATIONS
  • CLINICAL SPECTRUM
  • CATALYTIC SUBUNIT
  • PHENOTYPE

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