The large clinical overlap between DiGeorge syndrome and velo-cardio-facial syndrome suggests an aetiological connection. DiGeorge syndrome is associated with microdeletions of chromosome 22q11 and is therefore likely to be caused by reduced dosage of genes within this region. We present preliminary data that velocardiofacial syndrome patients have similar chromosome deletions, a finding consistent with the hypothesis that these disorders represent part of a spectrum of abnormalities seen with monosomy for 22q11.