Autism-linked CHD gene expression patterns during development predict multi-organ disease phenotypes

Recent large-scale exome sequencing studies have identified mutations in several members of the CHD (Chromodomain Helicase DNA-binding protein) gene family in neurodevelopmental disorders. Mutations in the CHD2 gene have been linked to developmental delay, intellectual disability, autism and seizures, CHD8 mutations to autism and intellectual disability, whereas haploinsufficiency of CHD7 is associated with executive dysfunction and intellectual disability. In addition to these neurodevelopmental features, a wide range of other developmental defects are associated with mutants of these genes, especially with regards to CHD7 haploinsufficiency, which is the primary cause of CHARGE syndrome. Whilst the developmental expression of CHD7 has been reported previously, limited information on the expression of CHD2 and CHD8 during development is available. Here, we compare the expression patterns of all three genes during mouse development directly. We find high, widespread expression of these genes at early stages of development that gradually becomes restricted during later developmental stages. Chd2 and Chd8 are widely expressed in the developing central nervous system (CNS) at all stages of development, with moderate expression remaining in the neocortex, hippocampus, olfactory bulb and cerebellum of the postnatal brain. Similarly, Chd7 expression is seen throughout the CNS during late embryogenesis and early postnatal development, with strong enrichment in the cerebellum, but displays low expression in the cortex and neurogenic niches in early life. In addition to expression in the brain, novel sites of Chd2 and Chd8 expression are reported. These findings suggest additional roles for these genes in organogenesis and predict that mutation of these genes may predispose individuals to a range of other, non-neurological developmental defects.