SLC6A1 and cancer: The evolutionary hotspot in the DNA binding domain of GAT1 identified in this study is reminiscent of hotspots in transcriptional regulators important in tumorigenesis including recurrent missense mutations in the DNA binding domain of TP53, a driver in the majority of human cancers (Freed-Pastor and Prives, 2012), and CTCF, a poly-zinc finger transcription factor regulating oncogenes and tumor suppressor genes (Ong and Corces, 2014).