This loop explains the overlapping phenotypes of four syndromes: Duane-radial ray syndrome with SALL4 mutations (MIM 607323); Fanconi anemia (MIM 227650); Holt-Oram syndrome with TBX5 mutations (MIM142900); and Townes-Brocks syndrome with SALL1 mutations (MIM 107480). This evidence concerns the gene SALL1 and Townes-Brocks syndrome.