3q29 microduplication syndrome: Clinical and molecular description of eleven new cases

Interstitial duplications of 3q29 have recently been described in association with a new genetic syndrome characterized by a neurodevelopmental phenotype. A total of 16 individuals with the 3q29 duplication have been reported in the literature with clinical features that include intellectual disability, language delay, epilepsy, structural brain anomalies, micro/macrocephaly, generalized obesity, ocular abnormalities, distinctive facial features, cleft palate, and musculoskeletal anomalies. In this paper, we summarize the current literature and present eleven additional cases from nine families with the 3q29 microduplication identified by microarray analysis at the Cincinnati Children's Hospital Medical Center Laboratory of Genetics and Genomics. Three diagnoses were made prenatally, making this the first case series to describe 3q29 duplications incidentally identified during the prenatal period. We further delineate the minimal region of overlap previously described in the literature and explore the modifying effects of “second hit” genetic aberrations, which were frequent in our cohort.