Mutations in TAF8 cause a neurodegenerative disorder

Item Type:	Article
Title:	Mutations in TAF8 cause a neurodegenerative disorder
Creators Name:	Wong, K.M. and Jepsen, W.M. and Efthymiou, S. and Salpietro, V. and Sanchez-Castillo, M. and Yip, J. and Kriouile, Y. and Diegmann, S. and Dreha-Kulaczewski, S. and Altmüller, J. and Thiele, H. and Nürnberg, P. and Toosi, M.B. and Akhondian, J. and Ghayoor Karimiani, E. and Hummel-Abmeier, H. and Huppke, B. and Houlden, H. and Gärtner, J. and Maroofian, R. and Huppke, P.
Abstract:	TAF8 is part of the transcription factor II D complex, composed of the TATA-binding protein and 13 TATA-binding protein-associated factors (TAFs). Transcription factor II D is the first general transcription factor recruited at promoters to assemble the RNA polymerase II preinitiation complex. So far disorders related to variants in 5 of the 13 subunits of human transcription factor II D have been described. Recently, a child with a homozygous c.781-1G>A mutation in TAF8 has been reported. Here we describe seven further patients with mutations in TAF8 and thereby confirm the TAF8 related disorder. In two sibling patients, we identified two novel compound heterozygous TAF8 splice site mutations, c.45+4A > G and c.489G>A, which cause aberrant splicing as well as reduced expression and mislocalization of TAF8. In five further patients, the previously described c.781-1G > A mutation was present on both alleles. The clinical phenotype associated with the different TAF8 mutations is characterized by severe psychomotor retardation with almost absent development, feeding problems, microcephaly, growth retardation, spasticity and epilepsy. Cerebral imaging showed hypomyelination, a thin corpus callosum and brain atrophy. Moreover, repeated imaging in the sibling pair demonstrated progressive cerebral and cerebellar atrophy. Consistently, reduced N-acetylaspartate, a marker of neuronal viability, was observed on magnetic resonance spectroscopy. Further review of the literature shows that mutations causing a reduced expression of transcription factor II D subunits have an overlapping phenotype of microcephaly, developmental delay and intellectual disability. Although transcription factor II D plays an important role in RNA polymerase II transcription in all cells and tissues, the symptoms associated with such defects are almost exclusively neurological. This might indicate a specific vulnerability of neuronal tissue to widespread deregulation of gene expression as also seen in Rett syndrome or Cornelia de Lange syndrome.
Keywords:	TAF8, TFIID, Neurodegenerative, Psychomotor Retardation
Source:	Brain
ISSN:	0006-8950
Publisher:	Oxford University Press
Volume:	145
Number:	9
Page Range:	3022-3034
Date:	September 2022
Additional Information:	Copyright © The Author(s) 2022. Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com
Official Publication:	https://doi.org/10.1093/brain/awac154
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