22q13 microduplication in two patients with common clinical manifestations: A recognizable syndrome?

We report here on two unrelated patients (Patients 1 and 2) with a cryptic microduplication involving a 22q13 segment. Both patients manifested infantile hypotonia, developmental delay, and growth deficiency. In addition, an abnormal signal intensity area was detected in the frontal white matter of Patient 2 by brain MRI. Whole-genome microarray comparative genomic hybridization for Patient 1 and fluorescence in situ hybridization analysis with 22q-subtelomeric probes performed in both patients showed a submicroscopic 22q13 duplication that involved the SHANK3 gene. The duplication in Patient 1 was de novo type, while that in Patient 2 was derived from a familial 17;22 translocation. The presence of common clinical manifestations in the two patients with the common duplicated region led to a conclusion that 22q terminal duplication is a recognizable clinical entity, that is, the 22q13 microduplication syndrome.