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Genetics and ID (genotype-environment correlation (reaction range: genetic…
Genetics and ID
genotype-environment correlation
developmental systems view
epigenetics: external modifications that turn genes on/off
modify how cells read genes--how much protein is produced, which hormones are released, etc.
epigenetic mechanisms
DNA methylation: extra methyl group added to molecule which stops certain genes from being read
histone modification: proteins wrap around DNA too tightly to read properly
parents give genes + home environment
home environment is derived from their genes... which are also inherited
environments = function of personality
reactive interaction: different persons exposed to the same environment experience/interpret/react differently
proactive interaction: individuals select and construct different environments
evocative interaction: personality evokes distinctive responses from others
bidirectional influences
reaction range: genetic makeup leaves possibilities of
a number of developmental outcomes
environmental factors determine development over time
limited by genetic boundaries similar to stretching a rubber band
environment ALONE doesn't cause ID
IQ may be low but kids bounce back quickly in new environments
however if genetic anomaly is undetected, will quickly manifest in poor environment
possible genetic mechanisms for ID
major gene effects: large and rare mutations
inherited genes for cognitive ability and polygenetic traits that are risk factors
aggregation of mild deleterious mutations: small subtle effects... ID with unknown causes
genetics
genotype: particular set of genes inherited from parents
phenotype: the expression of the genotype
get 23 chromosomes from each parent through meiosis
some chromosomal abnormalities interfere with development
non-hereditary mutations (problem during meiosis)
studying and screening for ID
strategies for studying ID
top-down approach: observe behaviour and infer gene cxn
bottom-um: observe genes and infer behaviour cxn
endophenotypes: study processes suspected to be linked to genes and behaviour
screening... who should be involved in the decision?
can lead to termination
not informed about ID and what long-term life looks like, pressured to make fast choice and influenced by societal perceptions/constructions
balance of individual rights and social benefit
costs society $$ for programs and support
all individuals have the right to be born/educated/accepted
paternalism: professionals are biased to try and fix/erradicate
identifying ID can also help: fix abnormalities, prepare parents, provide recurrence risks, reduce termination
screening and diagnostic tests
want high detection rate/sensitivity: ability to pick up on pregnancies with the disease
want low false positive rate: leads to anxiety, more tests, and termination
want high PPV: positive predictive value--measure of reliability of a positive screen result
heredity
inheritance--transmission of maternally and paternally derived genes
monogenetic traits and polygenetic traits
giftedness and ID parallels
