A loss-of-function mutation p.T52S in RIPPLY3 is a potential predisposing genetic risk factor for Chinese Han conotruncal heart defect patients without the 22q11.2 deletion/duplication

Hypoparathyroidism Associated with Benign Thyroid Nodules in DiGeorge-like Syndrome: A Rare Case Report and Literature Review

BACKGROUND

DiGeorge-like syndrome (DGLS) is a rare genetic disorder due to the presence of the same classical clinical manifestations of DiGeorge syndrome (DGS) without its typical deletion. In the DGLS phenotype, hypoparathyroidism seldom occurs and is considered rare. In DGS, hypocalcemia affects up to 70% of patients, and a considerable share often has asymptomatic thyroid abnormalities.

CASE PRESENTATION

In this study, we describe an unusual case of a 16-year-old patient with DGLS due to a duplication of 365 kb in the 20p11.22 region, affected by hypoparathyroidism associated with thyroid nodule. The intraoperative parathyroid evaluation ruled out agenesis as a cause of hypoparathyroidism. In addition, we carried out a thorough literature review from 2010 to 2023 of DGLS cases using specific keywords, such as "22q11.2 deletion syndrome", "Di- George-like Syndrome", "hypoparathyroidism", "thyroid", and "children", analyzing 119 patients with DGLS.

CONCLUSION

Interestingly enough, the present case represents, to our knowledge, the first report of a patient with DGLS associated with hypoparathyroidism and the presence of thyroid nodules where an intraoperative observation reported a non-functional parathyroid gland.

The transcription factor Sox7 modulates endocardiac cushion formation contributed to atrioventricular septal defect through Wnt4/Bmp2 signaling

Cardiac septum malformations account for the largest proportion in congenital heart defects. The transcription factor Sox7 has critical functions in the vascular development and angiogenesis. It is unclear whether Sox7 also contributes to cardiac septation development. We identified a de novo 8p23.1 deletion with Sox7 haploinsufficiency in an atrioventricular septal defect (AVSD) patient using whole exome sequencing in 100 AVSD patients. Then, multiple Sox7 conditional loss-of-function mice models were generated to explore the role of Sox7 in atrioventricular cushion development. Sox7 deficiency mice embryos exhibited partial AVSD and impaired endothelial to mesenchymal transition (EndMT). Transcriptome analysis revealed BMP signaling pathway was significantly downregulated in Sox7 deficiency atrioventricular cushions. Mechanistically, Sox7 deficiency reduced the expressions of Bmp2 in atrioventricular canal myocardium and Wnt4 in endocardium, and Sox7 binds to Wnt4 and Bmp2 directly. Furthermore, WNT4 or BMP2 protein could partially rescue the impaired EndMT process caused by Sox7 deficiency, and inhibition of BMP2 by Noggin could attenuate the effect of WNT4 protein. In summary, our findings identify Sox7 as a novel AVSD pathogenic candidate gene, and it can regulate the EndMT involved in atrioventricular cushion morphogenesis through Wnt4-Bmp2 signaling. This study contributes new strategies to the diagnosis and treatment of congenital heart defects.

Effect of retinoic acid signaling on Ripply3 expression and pharyngeal arch morphogenesis in mouse embryos

BACKGROUND

Pharyngeal arches (PA) are sequentially generated in an anterior-to-posterior order. Ripply3 is essential for posterior PA development in mouse embryos and its expression is sequentially activated in ectoderm and endoderm prior to formation of each PA. Since the PA phenotype of Ripply3 knockout (KO) mice is similar to that of retinoic acid (RA) signal-deficient embryos, we investigated the relationship between RA signaling and Ripply3 in mouse embryos.

RESULTS

In BMS493 (pan-RAR antagonist) treated embryos, which are defective in third and fourth PA development, Ripply3 expression is decreased in the region posterior to PA2 at E9.0. This expression remains and its distribution is expanded posteriorly at E9.5. Conversely, high dose RA exposure does not apparently change its expression at E9.0 and 9.5. Knockout of retinaldehyde dehydrogenase 2 (Raldh2), which causes more severe PA defect, attenuates sequential Ripply3 expression at PA1 and reduces its expression level. EGFP reporter expression driven by a 6 kb Ripply3 promoter fragment recapitulates the endogenous Ripply3 mRNA expression during PA development in wild-type, but its distribution is expanded posteriorly in BMS493-treated and Raldh2 KO embryos.

CONCLUSION

Spatio-temporal regulation of Ripply3 expression by RA signaling is indispensable for the posterior PA development in mouse.