Editor,—We read in a recent issue of the journal the paper by Trainer et al on 22q11 microdeletion (del22q11) in patients with tetralogy of Fallot.1 Del22q11 was detected in patients with classic and mild DiGeorge/velocardiofacial syndrome, but also in ‘non-dysmorphic’ patients. The authors suggest that fluorescence in situ hybridisation (FISH) for del22q11 should routinely be performed in all patients with tetralogy of Fallot. Our experience on a large sample of patients with isolated conotruncal heart defects (CTHDs) demonstrated, on the contrary, that …