Dysfunctional SEMA-PLXN signaling pathways or mutations in genes carrying these proteins were found in neurodevelopmental disorders, such as autism [146,147,148,149,150], Rett syndrome [151,152] and schizophrenia [153,154] to name a few, and an increasing number of studies indicates that they may mediate irreversible damages in neurodegenerative diseases, having either early or late onset. The gene discussed is SEMA6A; the disease is autism.