Phenotype Heterogeneity in 3q29 Microduplication Syndrome

3q29 microduplication syndrome is characterized by widely variable clinical presentation, but generally mild features. Developmental delay, particularly speech, and intellectual disability, eye abnormalities and heart defects are more frequently seen in affected individuals, although it is difficult to delineate a recognisable pattern. We describe a clinical case with a 1.65Mb duplication at 3q29 (chr3:195,979,518-197,638,922, GRCh37) identified by aCGH. The uncharacteristically late onset of the 34 years-old woman is marked by mild intellectual disability, progressive cortical atrophy and recurrent mucosal infections with Candida albicans. The gene content of the duplicated region-29 genes, including PAK2, DLG1, BDH1, FBXO45 and TFRC-seems closely linked to neuronal development and synaptic function, explaining brain and eye development related findings. We speculate on the possible involvement of genes like RNF168 in the aetiology of immunodeficiency. In-depth studies are needed to understand the pathophysiological mechanisms leading to the traits seen in this very rare syndrome.