Prevalence of duplications and deletions of the 22q11 DiGeorge syndrome region in a population-based sample of infants with cleft palate

The prevalence of duplications and deletions of the 22q11.2 (DiGeorge syndrome) region was studied among babies born in Norway with open cleft palate without cleft lip (cleft palate only, CPO). During a 5-year period (1996-2001), there were 245 live births with CPO that were referred for surgery. DNA was available from 174 cases with overt cleft palate. DNA copy number was analyzed with the multiplex ligation-dependent probe amplification (MLPA) technique, and an unambiguous result was obtained in 169 (97%) of the samples. We found no 22q11.2 duplications, and one known, and two previously undiagnosed cases with 22q11.2 deletions. All three del22q11-syndrome cases also had heart malformations, which represent one-third of the 10 babies with heart malformations in our study population. The prevalence of del22q11-syndrome among babies with cleft palate with or without additional malformations was 1 of 57 (1.8%). Because the prevalence of CPO in the 35 22q11.2 duplication cases published was 20%, we also investigated if dup22q11-testing was warranted in this group. However, no 22q11.2 duplications were found, indicating that the duplication cases ascertained so far might not be representative of the dup22q11-group as a whole. We conclude that neither del22q11 nor dup22q11 testing is warranted in babies with overt cleft palate as the only finding.