(a) Schematic representation of TBR1 indicating changes found in sporadic ASD cases. (b) Sequence alignment of the T-box domains of TBR1 in human (UniProt accession Q16650), mouse (Q64336), zebra finch (deduced from genome sequence), xenopus (Q0IHV5) and zebrafish (B5DE34). (c) Sequence alignment of the T-box domains of human TBR1 (Q16650), T protein (O15178), TBX1 (O43435), TBX3 (O15119), TBX6 (O95947). Conserved residues are highlighted in green. Red arrows indicate residues mutated in sporadic ASD cases. The blue arrow indicates the first residue absent in the truncated S351X variant.