Clinical variability of the 22q11.2 duplication syndrome.

The 22q11.2 duplication syndrome is an extremely variable disorder with a phenotype ranging from normal to learning disability and congenital defects. Both patients with a de novo 22q11.2 duplication and patients in whom the duplication has been inherited from a phenotypically normal parent have been reported. In this study we present two familial cases with a 3Mb 22q11.2 duplication detected by array-CGH. We also review the findings in 36 reported cases with the aim of delineating the phenotype of the 22q11.2 duplication syndrome. In a majority of the reported cases where parents have been tested, the duplication seems to have been inherited from a normal parent with minor abnormalities. With this in mind we recommend that family members of patients with a 22q11.2 duplication to be tested for this genetic defect.