L15Q mutation
The novel mutation Lue15Gln, reported for the first time in this study, is located in the exon 2 of the TBX5 gene. It is a missense mutation that replaced the leucine as nonpolar amino acid at the end of the N protein TBX5 and out of the T-box motif, with a glutamine amino acid. Although the Lue15Gln mutation occurred outside of the T-box, structural stability prediction of this mutation showed it causes protein instability. On the other hand, although the PolyPhen-2 analysis predicted this mutation is benign, it does reduce the stability of the protein and is found with ASD and PS in this study (Table 3). TBX5 protein crystal structures deposited in the Protein Data Bank are incomplete for the first 36 residues, therefore information for L15Q from PDB and PDBJ is unavailable.