Autism spectrum disorder (ASD) for identical twins only has an 88% concordance rate (both have it), revealing an environmental rather than a genetic factor must be responsible for causing it.  Some concordant identical twins share ASD to varying degrees, suggesting different prenatal environments exist between them, which occurs when they have separate placentas (about 30% of the time).

Published results were collected and analyzed to reach this conclusion.

Scientists know excessive increases in extra-axial cerebral spinal fluid (CSF) detected by MRI in the brains of 6- and 12-month-old infants later diagnosed at 2 years with ASD predict which children will develop it. Additionally, placental inclusions are predictive of ASD and the human papillomavirus (HPV) can infect the trophoblast cells of placentas and transmit HPV to the fetus. HPV can then infect the epithelial cells of the brain’s choroid plexus, a centrally located lining inside the brain responsible for producing CSF via the SLC4A10 gene product found to be increased in children with ASD. HPV’s incorporation into the host’s genome causes genetic changes – duplications and deletions of genes - making ASD appear to be genetic when it is not. HPV’s E6 protein activates the mTORC1 pathway and inactivates p53 both also associated with ASD and Rapamycin inhibits the mTORC1 pathway and is used to treat both ASD and cancers. Male placentas tend to implant close to the cervix (low-lying) three times more often than female placentas paralleling the ASD ratio of ~3:1 for boys to girls. Finally, the Australian HPV school vaccination program that began in 2007 for girls aged 11-12 might explain why the incidence of ASD in the 0-4-year-old children did not increase from 2010 to 2015.

Besides cervical, oral, skin, and various cancers, we should investigate if HPV is involved in causing other diseases and disorders like ASD.

Keywords: Autism, Human Papilloma Virus, prenatal environment, Placenta, Choroid plexus, Cervical infection