protein family, which has shown down-regulated expression in transformed B lymphocytes from autism samples15. We have further extended this finding by directly demonstrating lowered SEMA5A gene expression in autism brain tissue. This is an attractive candidate gene given that its protein is a bifunctional guidance molecule, which is both attractive and inhibitory for developing neurons. Interestingly, the SEMA5A receptor is plexin B3, which also signals through the tyrosine kinase MET, a previously reported autism susceptibility gene20,21.
