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This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Small chromosomal duplications involving 7q36.3 have rarely been reported. This clinical report describes four individuals from a three-generation family with agenesis of the corpus callosum (ACC) and a 0.73 Mb duplication of 7q36.3 detected by array CGH. The 7q36.3 duplication involves two genes: RNA Binding Motif Protein 33 (RBM33) and Sonic Hedgehog (SHH). Most affected family members had mild intellectual disability or borderline intellectual functioning, macrocephaly, a broad forehead, and widely spaced eyes. Two individuals had a Chiari type I malformation. This is the first family reported with ACC associated with a small duplication of these genes. While we cannot establish causation for the relationship between any single gene and the ACC in this family, there is a role for SHH in the formation of the corpus callosum through correct patterning and assembly of the commissural plate, and these data concur with vertebrate studies showing that a gain of SHH expands the facial primordium.

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