It is GMS
From my Uni powerpoint (given by Paed so accepted stuff):
Causes of Autism
Environmental factors
a. Prenatal
Maternal infections (Rubella)
Obstetric factors
Drug (anti-convulsants in pregnancy)
b. Postnatal
Infections (encephalitis)
- Genetic factors
Genetics and Autism
Genetic factors play an important role in causation
of ASD.
Family and twin studies:
[Smalley et al 1988
Bailey et al 1995
Folstein and Rutter 1977
Stefanburg et al 1989]
Concordance rates for MZ twins significantly higher
than DZ twins.
Genetics and Autism
Autistic sibling/mild phenotype in other family members.
Mild phenotype
- Male siblings more frequently affected
- Not associated with epilepsy/learning difficulties
- Mild ↓ verbal IQ
Not likely to be due to a single gene
Possibly due to interaction of small number of specific genes located on following chromosomes ? 2q, 7q, 4p and 19p
Individuals Requesting Genetic Counselling for Autism
Three groups:
Parents with an affected child.
Couples with an affected relative.
Individuals who have diagnosis of autism or Asperger?s syndrome.
Importance of Gene Search
Identify proteins and function
Identify factors affecting phenotypic expression
Improve diagnosis
Improve counselling
(One child with ASD risk second child → 5 to 6%)
Uncertainties
Risk of ASD in parents with ASD ? ranges from 5% (sibling risk) to 50% (auto dominant).
Recurrence risk in second and third degree relatives much lower than 1%.
No information on recurrence risk of AS in families with one individual with this condition.
?Slight increase risk for either of disorders with risk for autism lower than Asperger?s syndrome.
Genetic Disorder and ASD
5-10% autism have identifiable medical condition
Fragile X
Rett?s syndrome
Tuberous sclerosis
Neurofibromatosis
PKU
Other chromosomal disorder
Hope that makes sense C&P out of powerpoint