Autism Spectrum disorder

Question 1

Reductionism

Answer 1

focus on genetics leads to over analysis of cause - effect of gene variations/mutations. Very heterogenous disorder - environmental impacts too

Question 2

Autistic diad

Answer 2

Social deficits - communication and social interaction.
Repetitive and restrictive behaviours and interests.

Question 3

environmental risk factors

Question 4

Brain structure changes

Answer 4

6 month old children some siblings of ASD. Blind to diagnosis study.

Greater brain volume (cortex) between 12 - 24 months. Brain overgrowth linked to ASD development.

Question 5

Genetics

Answer 5

Identical twins 80-90% concordance.
Autosomal recessive, autosomal dominant both can lead to ASD when inherited.
X linked variation - 4:1 male to female ratio of ASD.
Copy number variations also lead to mutation - variation

Question 6

Polygenic risk model

Answer 6

Many inherited variants contribute to ASD but all have small effect - combined with environment to cross ‘threshold of risk’.

Question 7

Major gene model

Answer 7

Clear mutation in gene considered enough to cause ASD in individual. Either inherited or mutation in utero.
DE NOVO variations are so potent that heritability to ASD link is very high.

Question 8

Synaptic transmission

Answer 8

Gene with mutation affects function of protein - many genes are operating for function of synapses.
Neurohglin 3/4 genes.
Neuroligins are cell adhesion molecules at synapses - thought to contribute to setting exhitatory/inhibitory ratio at synapses.

Question 9

Genome sequencing

Answer 9

Sequence the exome - protein coding section of dna.
Large scale sequencing studies highlight 102 genes implicated with ASD - mainly to do with synaptic development.

Question 10

Recent PET scan study

Answer 10

Lower synnaptic density found within adults with ASD.