In addition to single nucleotide mutations, there are several reported cases of contiguous microdeletions at 12q24.21 locus encompassing both TBX3 and TBX5 genes and giving rise to phenotypes that combine UMS and Holt-Oram syndrome features (Borozdin et al., 2006; Alby et al., 2013; Bogarapu et al., 2014; Iwanicka-Pronicka et al., 2016). Here, TBX5 is linked to Holt-Oram syndrome.