KIF13B and hereditary spastic paraplegia: Other researchers have analyzed the genomes of two consanguineous families with complex HSP (concomitant mental retardation, epilepsy) and found that there is a large deletion on 8p12-p11.21, and that the KIF13B gene, which is located within this interval, may be a functional candidate gene for this form of HSP (Al-Yahyaee et al., 2006).