4 - Transchromosomic rodent models of Down syndrome: TcHSA21rat vs TcMAC21

Poster Board Number: 4
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Co-authors:

Roger Reeves - Johns Hopkins Medical School; Joan Richtsmeier - Distinguished Professor, Anthropology, PSU

Abstract Body :Down syndrome (DS) is a complex condition caused by an extra copy of human chromosome 21 (HSA21). The recently developed transchromosomic rodent models of DS, TcMAC21 mice and TcHSA21rat, provide an excellent opportunity to further understand the various phenotypic anomalies associated with DS. This study focuses on theTcHSA21rat model of DS. TcHSA21rat contains a freely segregating EGFP-labeled HSA21 and carries ~93% of HSA21 protein-coding genes. Both models of DS consistently express DS-like craniofacial malformations, however, no comparisons have been conducted between TcHSA21rat and TcMAC21 mice as yet. Using landmark-based geometric morphometrics, principal components, and multivariate regression analyses, we quantitatively compared the cranial morphology of TcHSA21rat relative to and their unaffected littermates with TcMAC21 mice and their respective euploids. Data comprised of forty 3D craniofacial coordinates taken on computed tomography scans of the TcHSA21rat and TcMAC21 datasets. The trisomic animals exhibit the pattern of craniofacial features that are associated with DS, however, the TcHSA21rat specimens show increased snout retraction (anterior-posteriorly) and neurocranial rounding (superior-inferiorly) relative to the TcMAC21 mice. We also tested for any size- and species-specific variation, and found that these two variables did not impact the pattern of DS-related shape changes in the trisomic rats and mice. Our findings further establish TcHSA21rat as a promising model for DS research on craniofacial anomalies.