@article {1013, title = {Novel variants in TUBA1A cause congenital fibrosis of the extraocular muscles with or without malformations of cortical brain development.}, journal = {Eur J Hum Genet}, volume = {29}, year = {2021}, month = {2021 May}, pages = {816-826}, abstract = {

Variants in multiple tubulin genes have been implicated in neurodevelopmental disorders, including malformations of cortical development (MCD) and congenital fibrosis of the extraocular muscles (CFEOM). Distinct missense variants in the beta-tubulin encoding genes TUBB3 and TUBB2B cause MCD, CFEOM, or both, suggesting substitution-specific mechanisms. Variants in the alpha tubulin-encoding gene TUBA1A have been associated with MCD, but not with CFEOM. Using exome sequencing (ES) and genome sequencing (GS), we identified 3 unrelated probands with CFEOM who harbored novel heterozygous TUBA1A missense variants c.1216C>G, p.(His406Asp); c.467G>A, p.(Arg156His); and c.1193T>G, p.(Met398Arg). MRI revealed small oculomotor-innervated muscles and asymmetrical caudate heads and lateral ventricles with or without corpus callosal thinning. Two of the three probands had MCD. Mutated amino acid residues localize either to the longitudinal interface at which α and β tubulins heterodimerize (Met398, His406) or to the lateral interface at which tubulin protofilaments interact (Arg156), and His406 interacts with the motor domain of kinesin-1. This series of individuals supports TUBA1A variants as a cause of CFEOM and expands our knowledge of tubulinopathies.

}, issn = {1476-5438}, doi = {10.1038/s41431-020-00804-7}, author = {Jurgens, Julie A and Barry, Brenda J and Lemire, Gabrielle and Chan, Wai-Man and Whitman, Mary C and Shaaban, Sherin and Robson, Caroline D and MacKinnon, Sarah and England, Eleina M and McMillan, Hugh J and Kelly, Christopher and Pratt, Brandon M and O{\textquoteright}Donnell-Luria, Anne and MacArthur, Daniel G and Boycott, Kym M and Hunter, David G and Engle, Elizabeth C} } @article {558, title = {MACF1 Mutations Encoding Highly Conserved Zinc-Binding Residues of the GAR Domain Cause Defects in Neuronal Migration and Axon Guidance.}, journal = {Am J Hum Genet}, volume = {103}, year = {2018}, month = {2018 12 06}, pages = {1009-1021}, abstract = {

To date, mutations in 15 actin- or microtubule-associated genes have been associated with the cortical malformation lissencephaly and variable brainstem hypoplasia. During a multicenter review, we recognized a rare lissencephaly variant with a complex brainstem malformation in three unrelated children. We searched our large brain-malformation databases and found another five children with this malformation (as well as one with a less severe variant), analyzed available whole-exome or -genome sequencing data, and tested ciliogenesis in two affected individuals. The brain malformation comprised posterior predominant lissencephaly and midline crossing defects consisting of absent anterior commissure and a striking W-shaped brainstem malformation caused by small or absent pontine crossing fibers. We discovered heterozygous de novo missense variants or an in-frame deletion involving highly conserved zinc-binding residues within the GAR domain of MACF1 in the first eight subjects. We studied cilium formation and found a higher proportion of mutant cells with short cilia than of control cells with short cilia. A ninth child had similar lissencephaly but~only subtle brainstem dysplasia associated with a heterozygous de novo missense variant in the spectrin repeat domain of MACF1. Thus, we report variants of the microtubule-binding GAR domain of MACF1 as the cause of a distinctive and most likely pathognomonic brain malformation. A~gain-of-function or dominant-negative mechanism appears likely given that many heterozygous mutations leading to protein truncation are included in the ExAC Browser. However, three de novo variants in MACF1 have been observed in large schizophrenia cohorts.

}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2018.10.019}, author = {Dobyns, William B and Aldinger, Kimberly A and Ishak, Gisele E and Mirzaa, Ghayda M and Timms, Andrew E and Grout, Megan E and Dremmen, Marjolein H G and Schot, Rachel and Vandervore, Laura and van Slegtenhorst, Marjon A and Wilke, Martina and Kasteleijn, Esmee and Lee, Arthur S and Barry, Brenda J and Chao, Katherine R and Szcza{\l}uba, Krzysztof and Kobori, Joyce and Hanson-Kahn, Andrea and Bernstein, Jonathan A and Carr, Lucinda and D{\textquoteright}Arco, Felice and Miyana, Kaori and Okazaki, Tetsuya and Saito, Yoshiaki and Sasaki, Masayuki and Das, Soma and Wheeler, Marsha M and Bamshad, Michael J and Nickerson, Deborah A and Engle, Elizabeth C and Verheijen, Frans W and Doherty, Dan and Mancini, Grazia M S} } @article {226, title = {Somatic mutations in cerebral cortical malformations.}, journal = {N Engl J Med}, volume = {371}, year = {2014}, month = {2014 Aug 21}, pages = {733-43}, abstract = {

BACKGROUND: Although there is increasing recognition of the role of somatic mutations in genetic disorders, the prevalence of somatic mutations in neurodevelopmental disease and the optimal techniques to detect somatic mosaicism have not been systematically evaluated.

METHODS: Using a customized panel of known and candidate genes associated with brain malformations, we applied targeted high-coverage sequencing (depth, >=200{\texttimes}) to leukocyte-derived DNA samples from 158 persons with brain malformations, including the double-cortex syndrome (subcortical band heterotopia, 30 persons), polymicrogyria with megalencephaly (20), periventricular nodular heterotopia (61), and pachygyria (47). We validated candidate mutations with the use of Sanger sequencing and, for variants present at unequal read depths, subcloning followed by colony sequencing.

RESULTS: Validated, causal mutations were found in 27 persons (17\%; range, 10 to 30\% for each phenotype). Mutations were somatic in 8 of the 27 (30\%), predominantly in persons with the double-cortex syndrome (in whom we found mutations in DCX and LIS1), persons with periventricular nodular heterotopia (FLNA), and persons with pachygyria (TUBB2B). Of the somatic mutations we detected, 5 (63\%) were undetectable with the use of traditional Sanger sequencing but were validated through subcloning and subsequent sequencing of the subcloned DNA. We found potentially causal mutations in the candidate genes DYNC1H1, KIF5C, and other kinesin genes in persons with pachygyria.

CONCLUSIONS: Targeted sequencing was found to be useful for detecting somatic mutations in patients with brain malformations. High-coverage sequencing panels provide an important complement to whole-exome and whole-genome sequencing in the evaluation of somatic mutations in neuropsychiatric disease. (Funded by the National Institute of Neurological Disorders and Stroke and others.).

}, keywords = {Cerebral Cortex, Classical Lissencephalies and Subcortical Band Heterotopias, DNA Mutational Analysis, Humans, Lissencephaly, Magnetic Resonance Imaging, Malformations of Cortical Development, Mutation, Periventricular Nodular Heterotopia}, issn = {1533-4406}, doi = {10.1056/NEJMoa1314432}, author = {Jamuar, Saumya S and Lam, Anh-Thu N and Kircher, Martin and D{\textquoteright}Gama, Alissa M and Wang, Jian and Barry, Brenda J and Zhang, Xiaochang and Hill, Robert Sean and Partlow, Jennifer N and Rozzo, Aldo and Servattalab, Sarah and Mehta, Bhaven K and Topcu, Meral and Amrom, Dina and Andermann, Eva and Dan, Bernard and Parrini, Elena and Guerrini, Renzo and Scheffer, Ingrid E and Berkovic, Samuel F and Leventer, Richard J and Shen, Yiping and Wu, Bai Lin and Barkovich, A James and Sahin, Mustafa and Chang, Bernard S and Bamshad, Michael and Nickerson, Deborah A and Shendure, Jay and Poduri, Annapurna and Yu, Timothy W and Walsh, Christopher A} }