Lecture 11 (Fragile X) Flashcards
Why is it called Fragile X?
Because one or both of the arms of the X chromosome are bent/broken
What kind of syndrome is Fragile X?
inherited
What is the leading inherited cause of Autism?
Fragile X
What are the physical abnormalities associated with Fragile X?
- Long Faces,
- Large Foreheads
- Large Ears
- Double Jointed
What is the risk to male offspring of an unaffected individual carrying the Fragile X gene? what is the risk to female offspring?
Male: risk = 38%
Female: risk = 16%
Why are Male more at risk for inheriting Fragile X than Females?
Because Females carry two copies of the X chromosome and Males only have 1
What does Anticipation mean when talking about Fragile X?
It means that subsequent generations it’s more likely for fragile X symptoms to appear and more likely for them to be severe
What year was the Fragile X gene isolated? What is it called?
1991
FMR-1 gene
What does Fragile X have in common with Huntington’s?
It is a repeat nucleotide sequence. Excessive repeats increase chances of damaging the X chromosome.
More than 55 copies = Fragile X
What was Robert Tryon’s 1940 Study on Rats?
He tried to breed rats for intelligence by selectively breeding rats who did well in a maze together and those who did poorly together for 17 generations.
What was the problem with Tryon’s selective breeding rat study?
He thought he was breeding for intelligence but another psychologist tested his intelligent and dumb rats in the same maze but submerged in water and suddenly the “dumb” rats became very good and the “intelligent” rats did poorly.
What he was selecting for probably wasn’t intelligence
What are the unintended consequences of selective breeding called? What is an example?
Pleiotropy
Ex: Silver foxes being bread to be more docile and manageable ended up also displaying all kinds of physical characteristics: curly tails, fluffy ears, smaller scull, smaller jaws/teeth, less stress hormone
What accounted for the difference in which strain of rats was labeled more aggressive?
Ginsberg: Handled them gently
Scott: Handled them roughly
What are Rats that are sensitive to Salt called?
What happened when they were put in a conflict/stress situation?
What does this suggest?
Dhal rats
They reacted as if they had consumed salt: High Blood Pressure, some died
We can be genetically vulnerable to one thing and vulnerable to something completely different
What was the risk factor for criminality in children in unstable homes?
birth problems
What is MAOA?
it’s an enzyme involved in the metabolism of dopamine norepinephrine
What does Low MAOA activity put you at risk for? under what conditions?
Low MAOA makes it more likely to be diagnosed with Antisocial and conduct disorder if there is childhood maltreatment
What variations of the serotonin transporter gene are there? How are they related to risk of depression?
two short forms
two long forms
one short and one long
If you have two short forms of the allele and you’re in a family with severe maltreatment you have a much higher risk of major depressive disorder (same thing shown for negative/stressful life events)
one short and one long also at risk
two long = not at risk
What is the COMT gene? What are it’s variations?
How does cannabis use affect these variations?
Involved in the breakdown of dopamine Gene that is related to schizophrenia Variations: Met/Met Val/Val Val/Met
smoking cannabis as a teenager increases your risk for schizophrenia if you have the Val/Val allelic variation
What is typology?
study of type & symbols
What did Sheldon believe about genes and body type? What are the 3 types?
he believed genes affect body type and body type controls personality
- Endomorphs: a person who has excess fat/round people
- Mesomorph: excess of muscle and bone
- Ectomorph: excess of nerve tissue, tall/thin
What 3 personality types are there according to Sheldon? Which body types are they associated with?
- Viserotonic: social, outgoing, relaxed
= endomorphic - Somatotonic: Athletic, Aggressive
=mesomorphic - Cerebratonic: Intelectual, sensitive, inhibited
=ectomorphic
What kinds of correlations did Sheldon find? What can we take from this?
He found high correlations
There are a lot of self fulfilling prophecies: our body predicts the way we are treated in our environment which predicts our bodies
Why study Biochemistry?
- Functional genetics
- Chemical anatomy of the Brain
- Pharmacology
