Neural Basis of Autism:
1. Run in the family sibling with autism, 5% likely that other sibling will have
2. In monozygotic twins (exact same DNA), one twin is 60% likely to have
autism if the other twin does (may show differences in symptoms, severity
a. Shows that it is not all genetics!
3. Many chromosomes involved:
a. Strong evidence for loci on chromosomes 7 and 17. Also evidence for
chromosomes 2, 5, 11, 15, 16 and X.
4. Many genes involved:
a. Serotonin transporter on chromosome 17 (regulates aggression and
b. Transcription factor (EN2) on chromosome 7 (regulates thousands of
genes, possibly why there are so many genes involved in autism?)
c. Genes associated with glutamate (key role in balance in the brain)
d. Neuroexin 1 on chromosome 11 (large body of evidence, involved in
5. Thalidomide environmental factor (given to pregnant women for morning
sickness, caused a variety of birth detects including higher incidence of
a. Whatever goes wrong in autism occurs early in development.
6. Ears are square in shape and lower on head, tops flopped over, ear
development is on 20 and 24 day of development which supports
argument that whatever happens in autism happens early.
7. Increased risk for propagnosia
8. Different face pattern scanning. Normally we look at eyes while autistic
individuals look all over.
9. Under activation of amygdala (normally activates in respon