ASD Flashcards
(15 cards)
Critiques of androgen theory of autism?
- multifactorial basis - likely
- correlation not causation
- ## inconsisten biomarker evidence
isnt’ ASD genetic?
The statement means that studies involving identical twins (monozygotic twins) show that if one twin has autism spectrum disorder (ASD), there is less than a 50% chance that the other twin will also have ASD. For non-identical twins (dizygotic twins), this likelihood is even lower.
This finding implies that:
Genetics alone does not fully account for ASD: Even though identical twins share nearly all their genetic material, the fact that the concordance rate is less than 50% indicates that genetics is not the sole factor in ASD development.
how does the ASD brain look like?
inc tot brain volume, more cerebral cortical gray matter (12%), and more cerebral (18%) and cerebellar (39%) white matter than normal,
what are genes involved in ASD?
mutations in ADNP lead to a developmental/autistic syndrome in childr
when is it diagnose
after age of 3
male female diff not due to reporting bias?
There is substantial evidence suggesting that biological differences between males and females contribute to the observed sex differences in ASD prevalence. Genetic and neurobiological factors may play a significant role, with males being more susceptible to developing ASD
Diagnostic Tools and Criteria Are Becoming More Inclusive:
Current diagnostic criteria, such as those outlined in the DSM-5, have been refined over time to be more inclusive of both males and females.
What are X-chromosome-related genetic mutations?
X-chromosome-related genetic mutations occur on the X chromosome. Males (XY) are more affected by X-linked mutations because they only have one X chromosome, while females (XX) may be carriers or show milder symptoms due to having two X chromosomes. These mutations can lead to conditions like Fragile X syndrome and Rett syndrome
which de novo genes involved in ASD?
Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition with a strong genetic component. Both rare and common genetic variants contribute to ASD. Here’s an overview of the key genes involved:
Rare Variants (High-Impact Genes)
These genes are implicated in ASD due to rare mutations, often de novo (not inherited):
Synaptic Function and Plasticity
SHANK3: Affects synaptic scaffolding and signaling, associated with Phelan-McDermid syndrome and ASD.
NRXN1: Involved in synapse formation and neurotransmitter release.
NLGN3/4: Code for neuroligins, crucial for synaptic communication.
What do twin studies suggest about the heritability of ASD?
Twin studies show high concordance rates in monozygotic twins (70–90%) vs. dizygotic twins (30–40%), indicating strong genetic influence in ASD.
Is there a single gene responsible for ASD?
No. ASD is polygenic, involving many genes each contributing small effects. There is no single “autism gene. Many involved in synapse formation, neuronal signaling, and chromatin remodeling.
Rare, high impact mutations?
In ~10–12% of ASD cases, rare de novo mutations or copy number variations (CNVs) in single genes (e.g., SHANK3, CHD8, NRXN1, NLGN3, NLGN4X) are present, but these are not common across the ASD population.
If ASD risk genes are on the X chromosome, why don’t females (XX) get ASD as often as males (XY)?
Because females have two X chromosomes (XX), while males have only one (XY).
If a mutation occurs on one X chromosome, females may be protected by the other normal copy, whereas males have no backup X — so the mutation is fully expressed.
Are most ASD cases caused by X linked mutations?
Rare de novo mutations (in both autosomes and sex chromosomes),
Polygenic inheritance across many genes (not limited to X),
And environmental interactions (e.g., maternal immune activation
What age is it diagnosed, ASD?
3 y old
Give examples of genes knocked out
Shank3 knockout mice, where deletion of the Shank3 gene causes ASD-like behaviors including social deficits and repetitive behavior
