APOE and autism: Downregulation of FOXP2 can cause impaired speech function and decreased executive function, and FOXP2 is also implicated in the development of autism.[33] Although apolipoprotein E is a major lipid transporter in the central nervous system that plays a crucial role in neural function recovery following traumatic brain injury, carrying the APOE-ε2 allele is significantly associated with increased behavioral issues, impaired social interactions, and restricted behavioral patterns.[34]