TBX5 and Abnormal cardiac septum morphology: Using experimentally determined chromatin interaction data from mesendoderm cells, we mapped this locus to the promoter of the transcription factor TBX5, rare variants of which cause autosomal-dominant Holt-Oram syndrome (MIM 142900), characterized by congenital cardiac septal defects and upper-limb anomalies (Basson et al., 1997; Li et al., 1997).