Defining the phenotypical spectrum associated with variants in TUBB2A

Stefanie Brock, Tim Vanderhasselt, Sietske Vermaning, Kathelijn Keymolen, Luc Régal, Romina Romaniello, Dagmar Wieczorek, Tim Matthias Storm, Karin Schaeferhoff, Ute Hehr, Alma Kuechler, Ingeborg Krägeloh-Mann, Tobias B. Haack, Esmee Kasteleijn, Rachel Schot, Grazia Maria Simonetta Mancini, Richard Webster, Shekeeb Mohammad, Richard J. Leventer, Ghayda MirzaaWilliam B. Dobyns, Nadia Bahi-Buisson, Marije Meuwissen, Anna C. Jansen, Katrien Stouffs

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Background Variants in genes belonging to the tubulin superfamily account for a heterogeneous spectrum of brain malformations referred to as tubulinopathies. Variants in TUBB2A have been reported in 10 patients with a broad spectrum of brain imaging features, ranging from a normal cortex to polymicrogyria, while one patient has been reported with progressive atrophy of the cerebellar vermis. Methods In order to further refine the phenotypical spectrum associated with TUBB2A, clinical and imaging features of 12 patients with pathogenic TUBB2A variants, recruited via the international network of the authors, were reviewed. Results We report 12 patients with eight novel and one recurrent variants spread throughout the TUBB2A gene but encoding for amino acids clustering at the protein surface. Eleven patients (91.7%) developed seizures in early life. All patients suffered from intellectual disability, and 11 patients had severe motor developmental delay, with 4 patients (36.4 %) being non-ambulatory. The cerebral cortex was normal in five individuals and showed dysgyria of variable severity in seven patients. Associated brain malformations were less frequent in TUBB2A patients compared with other tubulinopathies. None of the patients had progressive cerebellar atrophy. Conclusion The imaging phenotype associated with pathogenic variants in TUBB2A is highly variable, ranging from a normal cortex to extensive dysgyria with associated brain malformations. For recurrent variants, no clear genotype-phenotype correlations could be established, suggesting the role of additional modifiers.

Original languageEnglish (US)
Pages (from-to)33-40
Number of pages8
JournalJournal of medical genetics
Volume58
Issue number1
DOIs
StatePublished - Jun 22 2020
Externally publishedYes

Bibliographical note

Funding Information:
Funding Recruitment and sequencing of patient 11 was supported by the The Australian Genomics Health Alliance, which is funded by National Health and Medical Research Council and the Australian Government’s Medical Research Future Fund. ACJ is supported by a Senior Clinical Investigator Fellowship from FWO. SB, RR, GMSM, RL, GMM, WBD, NBB, MM, ACJ and KS are members of Neuro-MIG, the European Network for Brain Malformations, supported by COST (Action CA16118, www.neuro-mig.org). Published with the assistance of the Fondation Universitaire de Belgique.

Publisher Copyright:
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Keywords

  • clinical genetics
  • epilepsy and seizures
  • genetics
  • neurology
  • neurosciences

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't

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