Corpus Callosum Agenesis

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Georg Langs - One of the best experts on this subject based on the ideXlab platform.

  • disrupted developmental organization of the structural connectome in fetuses with Corpus Callosum Agenesis
    NeuroImage, 2015
    Co-Authors: Andras Jakab, Gregor Kasprian, Ernst Schwartz, Gerlinde M Gruber, Christian Mitter, Daniela Prayer, Veronika Schopf, Georg Langs
    Abstract:

    Abstract Agenesis of the Corpus Callosum is a model disease for disrupted connectivity of the human brain, in which the pathological formation of interhemispheric fibers results in subtle to severe cognitive deficits. Postnatal studies suggest that the characteristic abnormal pathways in this pathology are compensatory structures that emerge via neural plasticity. We challenge this hypothesis and assume a globally different network organization of the structural interconnections already in the fetal acallosal brain. Twenty fetuses with isolated Corpus Callosum Agenesis with or without associated malformations were enrolled and fiber connectivity among 90 brain regions was assessed using in utero diffusion tensor imaging and streamline tractography. Macroscopic scale connectomes were compared to 20 gestational age-matched normally developing fetuses with multiple granularity of network analysis. Gradually increasing connectivity strength and tract diffusion anisotropy during gestation were dominant in antero-posteriorly running paramedian and antero-laterally running aberrant pathways, and in short-range connections in the temporoparietal regions. In fetuses with associated abnormalities, more diffuse reduction of cortico-cortical and cortico-subcortical connectivity was observed than in cases with isolated callosal Agenesis. The global organization of anatomical networks consisted of less segregated nodes in acallosal brains, and hubs of dense connectivity, such as the thalamus and cingulate cortex, showed reduced network centrality. Acallosal fetal brains show a globally altered connectivity network structure compared to normals. Besides the previously described Probst and sigmoid bundles, we revealed a prenatally differently organized macroconnectome, dominated by increased connectivity. These findings provide evidence that abnormal pathways are already present during at early stages of fetal brain development in the majority of cerebral white matter.

Vittorio Bocola - One of the best experts on this subject based on the ideXlab platform.

B Blanc - One of the best experts on this subject based on the ideXlab platform.

  • prenatal diagnosis of fetal Corpus Callosum Agenesis by ultrasonography and magnetic resonance imaging
    Prenatal Diagnosis, 1998
    Co-Authors: C Dercole, Nadine Girard, Ludovic Cravello, L Boubli, Alain Potier, Charles Raybaud, B Blanc
    Abstract:

    Corpus Callosum Agenesis (CCA) was evaluated by ultrasound examination and magnetic resonance imaging (MRI) in 14 cases. Ultrasonography was able to suspect CCA by indirect signs but a definitive diagnosis of CCA was achieved in only four cases. MRI was able to diagnose complete CCA in 13 cases and showed absence of the posterior portion of the Corpus Callosum in one case. Additional neurological abnormalities including heterotopia, gyration anomaly, asymmetry of the cerebral hemispheres, and Dandy-Walker variant were documented in five cases, as well as an ocular anomaly which was present in one case, by MRI examination. Prenatal counselling for fetal Agenesis of the Corpus Callosum is difficult as the prognosis is uncertain. The association with other cerebral abnormalities increases the likelihood of a poor outcome and ultrasonographic assessment of the fetal brain is limited. We found MRI to be a safe and useful additional procedure to complement ultrasonographic diagnosis or suspicion of CCA. © 1998 John Wiley & Sons, Ltd.

Greg Lemke - One of the best experts on this subject based on the ideXlab platform.

  • vax1 mutation associated with microphthalmia Corpus Callosum Agenesis and orofacial clefting the first description of a vax1 phenotype in humans
    Human Mutation, 2012
    Co-Authors: Anne Slavotinek, Ryan Chao, Tomas Vacik, Mani Yahyavi, Hana Abouzeid, Tanya Bardakjian, Adele Schneider, Gary M Shaw, Elliott H Sherr, Greg Lemke
    Abstract:

    Vax1 and Vax2 have been implicated in eye development and the closure of the choroid fissure in mice and zebrafish. We sequenced the coding exons of VAX1 and VAX2 in 70 patients with anophthalmia/microphthalmia (A/M). In VAX1, we observed homozygosity for two successive nucleotide substitutions c.453G>A and c.454C>A, predicting p.Arg152Ser, in a proband of Egyptian origin with microphthalmia, small optic nerves, cleft lip/palate, and Corpus Callosum Agenesis. This mutation affects an invariant residue in the homeodomain of VAX1 and was absent from 96 Egyptian controls. It is likely that the mutation results in a loss of function, as the mutation results in a phenotype similar to the Vax1 homozygous null mouse. We did not identify any mutations in VAX2. This is the first description of a phenotype associated with a VAX1 mutation in humans and establishes VAX1 as a new causative gene for A/M. Hum Mutat 33:364-368, 2012. (C) 2011 Wiley Periodicals, Inc.

Nicola Tambasco - One of the best experts on this subject based on the ideXlab platform.

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