Editor—Malformations resulting from the adverse effects of 22q11 deletion are now recognised to be of one of the most important diagnostic categories in dysmorphology. The predictive value of this common deletion remains to be fully elucidated since even large reviews1 are by their nature subject to ascertainment bias. In our original report of familial heart disease associated with submicroscopic 22q11 deletion, which predated the routine availability of fluorescence in situ hybridisation (FISH), the carrier mother was dysmorphic but had a normal heart.2 We and others have drawn attention to the marked variability of the phenotype and the need to be alert to the possibility of subtle features in a parent.3-5 These observations raise the possibility of subclinical deletion being more common than has been recognised. This would have significance in genetic counselling when 22q11 deletion is detected in the first trimester as occurred in the case described below.

Following the recognition of a deletion 22q11 in III.2 (fig 1) diagnosed clinically as DiGeorge syndrome …