Fig 1.

a) A baby with an interrupted aortic arch introduced us to older brothers with the milder problems of coarctation and a ventricular septal defect respectively. Their mother had a normal heart, but had experienced psychiatric problems. The three children had inherited a 22q11 deletion from their mother and the characteristic facial features of this ‘contiguous gene syndrome’. Adapted with permission from Wilson DI, Cross IE, Goodship JA et al. DiGeorge syndrome with isolated aortic coarctation and isolated ventricular septal defect in three sibs with a 22q11 deletion of maternal origin. Br Heart J 1991;66:308–12. b) A duplicated segment of the long arm of chromosome 22 can cause misalignment at gamete formation. If a chromosomal crossover hits this section, it results in one chromosome with a deletion and one with duplication. If the gamete which receives the deleted chromosome results in a pregnancy, the baby will have 22q11 deletion syndrome.