Micro-CT has become the standard for the assessment of malformations in mouse embryos because it allows the visualisation of internal structures in the context of the intact embryo. Statistical comparison of volume differences is possible via manual segmentation of organs of interest from micro-CT scans, but this process is slow and laborious. Automated registration-based methods now exist that make the volumetric analysis of all organs feasible. Here, we expand the available atlases for use with the LAMA registration and analysis pipeline to include high-resolution population averages derived from phosphotungstic acid-stained C57BL/6J embryos and corresponding manually segmented atlases at embryonic stage (E) 12.5, E15.5, and E17.5. We report application of these population averages and atlases with the LAMA phenotyping pipeline to Wbp11 heterozygous null embryos, identifying defects previously reported in the cervical vertebrae, brain, nasal cavity, palate, liver and kidneys as well as a right aortic arch defects missed by manual analysis, and volume differences in the eyes and spinal cord. Finally, we report a high-resolution isolated E18.5 mouse heart population average and corresponding atlas that when applied to the Wbp11 line identified significant differences. These findings highlight the advantages of unbiased, volumetric and quantitative approaches in the analysis of mouse models of human disease.

Congenital heart defects (CHDs) occur in 50-75% of patients with 22q11.2 deletion syndrome (22q11.2DS), ranging from mild to severe manifestations. The genetic and environmental factors contributing to variable CHD phenotypes in 22q11.2DS are largely unknown. In this study, we used a mouse model of 22q11.2DS, termed Df1/+, to evaluate the effect of maternal vitamin A (VitA) dietary imbalance (supplementation or deficiency) on the incidence of aortic arch defects (AADs), which is a common type of CHD observed in both 22q11.2DS patients and Df1/+ mouse embryos. While most groups showed a previously observed 30% AAD incidence, two groups exhibited significantly higher rates: (1) Df1/+ embryos from WT mothers on a VitA-Supl diet (51% AADs) and (2) Df1/+ embryos from Df1/+ mothers on a VitA-Def diet (45% AADs). Thus, a low or high maternal VitA diet can increase the frequency of AADs in embryos depending on the maternal genotype. Transcriptomic analysis of the hearts of these high-risk embryos at embryonic day (E)18.5 revealed downregulation of key genes (Hdac3, Ptgds, Sirt5, Pfkm, and Lclat1) associated with energy metabolism pathways, such as oxidative phosphorylation and glycolysis, suggesting impaired cardiac recovery mechanisms. In conclusion, our findings demonstrate that altered VitA exposure can exacerbate AAD incidence in a maternal-genotype-dependent manner, highlighting the complex interplay between embryonic and maternal genetic background and environmental factors in CHDs associated with 22q11.2DS.

Background: Coarctation of the aorta (CoA) can either present alone as an isolated condition or in association with other aortic arch or cardiac anomalies. One percent of patients with CoA have concomitant an aberrant right subclavian artery (ARSA). Purpose: We report the case of a 35-year-old woman with uncontrolled hypertension who was found to have CoA and ARSA. Results: The patient was treated successfully using a hybrid procedure comprising ARSA ligation and subclavian to carotid transposition, followed by thoracic endovascular aortic repair. Conclusions: Patients with CoA should be carefully studied, considering the possible coexistence of other congenital aortic arch defects, such as ARSA. Hybrid repair is a safe and effective approach for this condition.

Successful embryogenesis relies on the coordinated interaction between genes and tissues. The transcription factors Pax9 and Msx1 genetically interact during mouse craniofacial morphogenesis, and mice deficient for either gene display abnormal tooth and palate development. Pax9 is expressed specifically in the pharyngeal endoderm at mid-embryogenesis, and mice deficient for Pax9 on a C57Bl/6 genetic background also have cardiovascular defects affecting the outflow tract and aortic arch arteries giving double-outlet right ventricle, absent common carotid arteries and interruption of the aortic arch. In this study we have investigated both the effect of a different genetic background and Msx1 haploinsufficiency on the presentation of the Pax9-deficient cardiovascular phenotype. Compared to mice on a C57Bl/6 background, congenic CD1-Pax9-/- mice displayed a significantly reduced incidence of outflow tract defects but aortic arch defects were unchanged. Pax9-/- mice with Msx1 haploinsufficiency, however, have a reduced incidence of interrupted aortic arch, but more cases with cervical origins of the right subclavian artery and aortic arch, than seen in Pax9-/- mice. This alteration in arch artery defects was accompanied by a rescue in third pharyngeal arch neural crest cell migration and smooth muscle cell coverage of the third pharyngeal arch arteries. Although this change in phenotype could theoretically be compatible with post-natal survival, using tissue-specific inactivation of Pax9 to maintain correct palate development whilst inducing the cardiovascular defects was unable to prevent postnatal death in the mutant mice. Hyoid bone and thyroid cartilage formation were abnormal in Pax9-/- mice. Msx1 haploinsufficiency mitigates the arch artery defects in Pax9-/- mice, potentially by maintaining the survival of the 3rd arch artery through unimpaired migration of neural crest cells to the third pharyngeal arches. With the neural crest cell derived hyoid bone and thyroid cartilage also being defective in Pax9-/- mice, we speculate that the pharyngeal endoderm is a key signalling centre that impacts on neural crest cell behaviour highlighting the ability of cells in different tissues to act synergistically or antagonistically during embryo development.

CHARGE syndrome is characterized by a pattern of congenital anomalies (Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth, Genital abnormalities, and Ear abnormalities). De novo mutations of chromodomain helicase DNA binding protein 7 (CHD7) are the primary cause of CHARGE syndrome. The clinical phenotype is highly variable including a wide spectrum of congenital heart defects. Here, we review the range of congenital heart defects and the molecular effects of CHD7 on cardiovascular development that lead to an over-representation of atrioventricular septal, conotruncal, and aortic arch defects in CHARGE syndrome. Further, we review the overlap of cardiovascular and noncardiovascular comorbidities present in CHARGE and their impact on the peri-operative morbidity and mortality in individuals with CHARGE syndrome.