Joan T. Richtsmeier

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Down syndrome (DS) is the most common genetic cause of mental retardation and affects many aspects of brain development. DS individuals exhibit an overall reduction in brain size with a disproportionately greater reduction in cerebellar volume. The Ts65Dn mouse is segmentally trisomic for the distal 12-15 Mb of mouse chromosome 16, a region that shows(More)
The "Down syndrome critical region" (DSCR) is a chromosome 21 segment purported to contain genes responsible for many features of Down syndrome (DS), including craniofacial dysmorphology. We used chromosome engineering to create mice that were trisomic or monosomic for only the mouse chromosome segment orthologous to the DSCR and assessed dysmorphologies of(More)
Analysis of biological forms using landmark data has received substantial attention recently. Much of the statistical work in this area has concentrated on the estimation of average form, average form difference, and average growth difference. From the statistical, as well as the scientific point of view, it is important that any estimate of a(More)
Apert syndrome is an autosomal dominant disorder characterized by malformations of the skull, limbs and viscera. Two-thirds of affected individuals have a S252W mutation in fibroblast growth factor receptor 2 (FGFR2). To study the pathogenesis of this condition, we generated a knock-in mouse model with this mutation. The Fgfr2(+/S252W) mutant mice have(More)
Mouse genetic models can be used to dissect molecular mechanisms that result in human disease. This approach requires detection and demonstration of compelling parallels between phenotypes in mouse and human. Ts65Dn mice are at dosage imbalance for many of the same genes duplicated in trisomy 21 or Down syndrome (DS), the most common live-born human(More)
Nontraditional or geometric morphometric methods have found wide application in the biological sciences, especially in anthropology, a field with a strong history of measurement of biological form. Controversy has arisen over which method is the "best" for quantifying the morphological difference between forms and for making proper statistical statements(More)
Apert syndrome is characterized by craniosynostosis and limb abnormalities and is primarily caused by FGFR2 +/P253R and +/S252W mutations. The former mutation is present in approximately one third whereas the latter mutation is present in two-thirds of the patients with this condition. We previously reported an inbred transgenic mouse model with the Fgfr2(More)
Computed tomography (CT) has brought to the craniofacial surgeon a three-dimensional representation of internal structures. CT scans provide visualization of anatomy for preoperative planning and postoperative evaluation. Beyond visualization, however, a CT scan enables assessment of measurements useful to clinicians and basic scientists. All measurement(More)
Evolutionary history of Mammalia provides strong evidence that the morphology of skull and brain change jointly in evolution. Formation and development of brain and skull co-occur and are dependent upon a series of morphogenetic and patterning processes driven by genes and their regulatory programs. Our current concept of skull and brain as separate tissues(More)
Down syndrome (DS) results from inheritance of three copies of human chromosome 21 (Hsa21). Individuals with DS have a significantly smaller brain size overall and a disproportionately small cerebellum. The small cerebellum is seen in Ts65Dn mice, which have segmental trisomy for orthologs of about half the genes on Hsa21 and provide a genetic model for DS.(More)