PSY2071 Lecture Notes - Lecture 6: Epigenetics, Dsm-5, Mental Disorder
5 Jun 2018
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• PSY2071 – Lecture – Week 6 – Gene-behaviour associationsassisting
people with neurodevelopment disorders requires an appreciation of the
while system - gene - brain - environment - behaviour
• neurodevelopment disorders
•
o arise from abnormalities in the growth and development of the
brain or central nervous system, which gives rise to disorder
cognitive function, such as emotion regulation, learning ability,
self-control and memory that unfolds as an individual develops
and grows
o are the result of impairments to the typical growth or development
of the brain and nervous system
o can be the result of
o
▪ intrauterine environment
▪ extrauterine environment - post birth
▪ genetics
▪
▪ chromosomal disorders - e.g. down’s syndrome
▪ single gene disorders
▪
▪ fragile X
▪ Williams syndrome
▪ multiple gene disorders - polygenic disorders
▪
▪ autism spectrum disorder
▪ ADHD
▪
▪ tourette’s syndrome
o how are they diagnosed
o
▪ problem behaviours flagged by the child’s caregiver or
teachers
▪ child sees a GP for assessment and referral to paediatrician,
psychologist
▪ diagnosis made by specialist paediatrician or child
psychiatrist - detailed assessment of the child’s behaviour
▪ diagnosis based on symptom presentation
• typical brain development
•
o our genes orchestrate generating new brain cells, getting them to
migrate to the right spots, forming connections between those
neurons and pruning back unnecessary connections
o once the brain is fully formed - our genes are responsible for
producing proteins in the brain such as neurotransmitters and
they receptors and maintaining the health of the cells in the brain
• genes and behaviour
•
o abnormal behaviour reflects abnormal brain function
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find more resources at oneclass.com
o genes - proteins - cells - circuits - psychiatric disorder
o genes
o
▪ a distinct sequence of DNA forming part of a chromosome
which is the blueprint for a protein e.g. neurotransmitter
o alleles
o
▪ alternative forms - variants of a gene
o SNPs - single nucleotide polymorphisms
o
▪ a variation in a single nucleotide that occurs at a specific
point in the genome
• the common disease-rare variant hypotheses
•
o theories about how these disorders arise
o predicts that disorders arise from common disease causing
variants
• heritability
•
o the amount a phenotypic trait varies in a population that can be
attributed to genetic variation among members of that population
o a phenotypic trait is an obvious and observable trait
o variation of a behavioural trait
o genetic variation - the number of different variants of a gene or
genes
o variation of a behavioural trait is attributed to genetic variation
o estimate heritability
o
▪ parents to offspring
▪ comparing siblings
▪ comparing twins
• fragile X
•
o a genetic condition
o single gene
o can result in intellectual disability, behavioural and learning
challenges and various physical characteristics - large ears,
o over half of individuals with fragile X meet criteria for autism
o males affected more than females
o causes
o
▪ expansions or lengthening of the FMR1 gene on the X
chromoozome
▪ when the gene lengthens it switches off production of a
protein, Fragile mental retardation protein or FMRP that is
involved in brain development and other functions
▪ what happens as a result of FMR1 gene mutation
▪
find more resources at oneclass.com
find more resources at oneclass.com
