Microduplication and triplication of 22q11.2: A highly variable syndrome

Twila M. Yobb, Martin J. Somerville, Lionel Willatt, Helen V. Firth, Karen Harrison, Jennifer MacKenzie, Natasha Gallo, Bernice E. Morrow, Lisa G. Shaffer, Melanie Babcock, Judy Chernos, Francois Bernier, Kathy Sprysak, Jesse Christiansen, Shelagh Haase, Basil Elyas, Margaret Lilley, Steven Bamforth, Heather E. McDermid

Research output: Contribution to journalArticlepeer-review

186 Scopus citations


22q11.2 microduplications of a 3-Mb region surrounded by low-copy repeats should be, theoretically, as frequent as the deletions of this region; however, few microduplications have been reported. We show that the phenotype of these patients with microduplications is extremely diverse, ranging from normal to behavioral abnormalities to multiple defects, only some of which are reminiscent of the 22q11.2 deletion syndrome. This diversity will make ascertainment difficult and will necessitate a rapid-screening method. We demonstrate the utility of four different screening methods. Although all the screening techniques give unique information, the efficiency of real-time polymerase chain reaction allowed the discovery of two 22q11.2 microduplications in a series of 275 females who tested negative for fragile X syndrome, thus widening the phenotypic diversity. Ascertainment of the fragile X-negative cohort was twice that of the cohort screened for the 22q11.2 deletion. We also report the first patient with a 22q11.2 triplication and show that this patient's mother carries a 22q11.2 microduplication. We strongly recommend that other family members of patients with 22q11.2 microduplications also be tested, since we found several phenotypically normal parents who were carriers of the chromosomal abnormality.

Original languageEnglish (US)
Pages (from-to)865-876
Number of pages12
JournalAmerican Journal of Human Genetics
Issue number5
StatePublished - May 2005

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)


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