<em>TFAP2E</em> is implicated in central nervous system, orofacial and maxillofacial anomalies

Abstract

<strong>Background</strong> Previous studies in mouse, <em>Xenopus</em> and zebrafish embryos show strong <em>tfap2e</em> expression in progenitor cells of neuronal and neural crest tissues suggesting its involvement in neural crest specification. However, the role of human transcription factor activator protein 2 (<em>TFAP2E</em>) in human embryonic central nervous system (CNS), orofacial and maxillofacial development is unknown.<br /> <strong>Methods</strong> Through a collaborative work, exome survey was performed in families with congenital CNS, orofacial and maxillofacial anomalies. Exome variant prioritisation prompted <em>TFAP2E</em> gene for functional analysis in zebrafish embryos. Embryonic morphology and development were assessed after antisense morpholino (MO) knockdown (KD), CRISPR/Cas9 knockout and overexpression of <em>tfap2e</em> in fluorescent zebrafish reporter lines using in vivo microscopy. Computational structural protein modelling of the identified human variants was performed.<br /> <strong>Results</strong> In total, exome survey identified novel or ultra- rare heterozygous missense variants in <em>TFAP2E</em> in seven individuals from five independent families with predominantly CNS, orofacial and maxillofacial anomalies. One variant was found de novo and another variant segregated in an affected multiplex family. Protein modelling of the identified variants indicated potential distortion of TFAP2E in the transactivation or dimerisation domain. MO KD and CRISPR/Cas9 knockout of <em>tfap2e</em> in zebrafish revealed hydrocephalus and a significant reduction of brain volume, consistent with a microencephaly phenotype. Furthermore, mRNA overexpression of TFAP2E indicates dosage-sensitive phenotype expression. In addition, zebrafish showed orofacial and maxillofacial anomalies following <em>tfap2e</em> KD, recapitulating the human phenotype.<br /> <strong>Conclusion</strong> Our human genetic data and analysis of Tfap2e manipulation in zebrafish indicate a potential role of <em>TFAP2E</em> in human CNS, orofacial and maxillofacial anomalies.