Mutations of TCF12, encoding a basic-helix-loop-helix partner of TWIST1, are a frequent cause of coronal craniosynostosis

Abstract

Craniosynostosis, the premature fusion of the cranial sutures, is a heterogeneous disorder with a prevalence of ~1 in 2, 200 (refs. 1,2). A specific genetic etiology can be identified in ~21% of cases 3 , including mutations of TWIST1, which encodes a class II basic helix-loop-helix (bHLH) transcription factor, and causes Saethre-Chotzen syndrome, typically associated with coronal URLs. ANNOVAR, http://www.openbioinformatics.org/annovar; GBrowse2, http://gmod.org/wiki/GBrowse; MRC-Holland, www.mrc-holland.com/pages/indexpag.html; PolyPhen-2, http://genetics.bwh.harvard.edu/pph2; SAMtools, http:// samtools.sourceforge.net. Accession codes.All cDNA numbering of TCF12 follows NCBI reference NM_207037.1, starting with A of the ATG initiation codon (=1). We used NM_207040.1 to design primers to the alternatively spliced first exon (9A). The genomic reference sequence is available from NC_000015.9. Europe PMC Funders GroupAuthor Manuscript Nat Genet. Author manuscript; available in PMC 2013 September 01. [4][5][6] . Starting with an exome sequencing screen, we identified 38 heterozygous TCF12 mutations in 347 samples from unrelated individuals with craniosynostosis. The mutations predominantly occurred in patients with coronal synostosis and accounted for 32% and 10% of subjects with bilateral and unilateral pathology, respectively. TCF12 encodes one of three class I E-proteins that heterodimerize with class II bHLH proteins such as TWIST1. We show that TCF12 and TWIST1 act synergistically in a transactivation assay, and that mice doubly heterozygous for loss-of-function mutations in Tcf12 and Twist1 exhibit severe coronal synostosis. Hence, the dosage of TCF12/TWIST1 heterodimers is critical for coronal suture development.Our exome sequencing approach focused on bilateral coronal craniosynostosis (Fig. 1a) because of previous evidence that this pathological group is loaded with cases of monogenic etiology 3 . We examined the variant lists from whole exome data 7 of seven unrelated patients with bilateral coronal synostosis, negative for previously described mutations 8 , for genes showing non-synonymous changes in two or more samples. Two samples had different heterozygous frameshift mutations in TCF12 (transcription factor 12; also known as HEB, HTF4 and ALF1) 9-11 ; one (Family #19) had a single nucleotide deletion and the other (#30) a 4-nucleotide deletion (details in Supplementary Table 1). The mutations were confirmed by dideoxy-sequencing of the original DNA samples (primary sequence results for all families are shown in Supplementary Fig. 1). In addition a text search of the exome sequence data revealed a novel T>A variant in TCF12 in a third sample (#22), located 20 nucleotides upstream of the start of exon 17. This variant was predicted to generate a cryptic splice acceptor site that was confirmed experimentally ( Supplementary Fig. 2a). Thus, we had identified different heterozygous disruptive mutations of TCF12 in 3 of 7 samples from patients with bilateral coronal synostosis. We interrogated oth...

Tcf12, A Member of Basic Helix-Loop-Helix Transcription Factors, Mediates Bone Marrow Mesenchymal Stem Cell Osteogenic Differentiation In Vitro and In Vivo

“…In the present study, we demonstrated that silencing Tcf12 significantly increased the osteogenic potential of BMSCs in vitro, thus indicating an inhibitory osteogenic activity of this transcription factor in BMSCs. Of note, these findings are consistent with previous reports indicating that mutation of Tcf12 leads to craniosynostosis .…”

“…Basic helix‐loop‐helix (bHLH) genes constitute a large family of transcription factors (TFs) found in eukaryotic organisms, which orchestrates cell‐fate specification, commitment and differentiation in multiple cell lineages during development . Tcf12 is a transcription factor member of the bHLH family that regulates a variety of biological processes including immune response, metastasis of colorectal cancer, cognitive function and craniosynostosis . Tcf12 (also named HEB) has two gene products, HEBa and HEBb.…”

A Higher Proportion of Craniosynostosis Genes Are Cancer Driver Genes

“…The participation of TF in tumorigenesis is widely studied (Darnell, 2002; Harris, 2002; Zheng and Blobel, 2011; Gupta et al, 2019), including the most famous TF p53 (TP53 gene) (Harris, 1993; Staib et al, 2003; Muller and Vousden, 2013). However, when the three gene lists are compared (TF, cancer driver, CRS), only one gene, TCF12 (Lee et al, 2012; Sharma et al, 2013), appears in all lists.…”

Prenatal Imaging of Craniosynostosis Syndromes

“…Though craniosynostosis is a feature of many syndromes, single sutural synostosis is most commonly an isolated, nonsyndromic finding [2]. Some of these nonsyndromic patients may have an underlying genetic etiology for their phenotype [3]. There may be overlap in the appearance of multisutural synsotosis among different syndromes, though characteristic associated hand dysmorphology may help to distinguish one from the other.…”