Because CDH10 and CDH9 are expressed at low levels in non-neural tissues (Supplementary Figs 6 and 7), we evaluated their messenger RNA distribution in human fetal brain by in situ hybridization. Multiple sagittally sectioned human fetal brains, each between 19 and 20 weeks gestation, were hybridized with riboprobes against CDH10 or CDH9. Results for CDH9, showing uniformly low levels of expression at the time points evaluated, were largely uninformative. In contrast, a marked pattern of enrichment for CDH10 was observed in the frontal cortex (Fig. 2a)—a region known to be important in ASDs. The expression pattern was similar to that for CNTNAP2 (contactin-associated protein-like 2)29, a molecule now well-established to be involved in the ASDs1. These results are consistent with previous work showing high levels of CDH10 in the human fetal brain30 and a prominent enrichment of Cdh10 mRNA in the anterior cortical plate of the developing mouse brain31.
