Functional variants in TBX2 are associated with a syndromic cardiovascular and skeletal developmental disorder. (2nd May 2018)

• Record Type: Journal Article
• Authors: Liu, Ning; Schoch, Kelly; Luo, Xi; Pena, Loren D M; Bhavana, Venkata Hemanjani; Kukolich, Mary K; Stringer, Sarah; Powis, Zöe; Radtke, Kelly; Mroske, Cameron; Deak, Kristen L; McDonald, Marie T; McConkie-Rosell, Allyn; Markert, M Louise; Kranz, Peter G; Stong, Nicholas; Need, Anna C; Bick, David; Amaral, Michelle D; Worthey, Elizabeth A; Levy, Shawn; Wangler, Michael F; Bellen, Hugo J; Shashi, Vandana; Yamamoto, Shinya
• Is Part Of: Human molecular genetics. Volume 27:Number 14(2018:Jul. 15)
• Page Start: 2454
• Page End: 2465
• Publication Date: 2018-05-02
• Subjects: Human molecular genetics -- Periodicals; Human chromosome abnormalities -- Periodicals; 572.8
• DOI: 10.1093/hmg/ddy146
• Languages: English
• ISSNs: 0964-6906

Abstract

Abstract: The 17 genes of the T-box family are transcriptional regulators that are involved in all stages of embryonic development, including craniofacial, brain, heart, skeleton and immune system. Malformation syndromes have been linked to many of the T-box genes. For example, haploinsufficiency of TBX1 is responsible for many structural malformations in DiGeorge syndrome caused by a chromosome 22q11.2 deletion. We report four individuals with an overlapping spectrum of craniofacial dysmorphisms, cardiac anomalies, skeletal malformations, immune deficiency, endocrine abnormalities and developmental impairments, reminiscent of DiGeorge syndrome, who are heterozygotes for TBX2 variants. The p.R20Q variant is shared by three affected family members in an autosomal dominant manner; the fourth unrelated individual has a de novo p.R305H mutation. Bioinformatics analyses indicate that these variants are rare and predict them to be damaging. In vitro transcriptional assays in cultured cells show that both variants result in reduced transcriptional repressor activity of TBX2. We also show that the variants result in reduced protein levels of TBX2. Heterologous over-expression studies in Drosophila demonstrate that both p.R20Q and p.R305H function as partial loss-of-function alleles. Hence, these and other data suggest that TBX2 is a novel candidate gene for a new multisystem malformation disorder.