3. genetic description Flashcards
family studies
passed from one generation to the next via genes
if inherited people who share genes share the disorder
% risk for developing Sz vs children with 2 Sz parents
1% vs 46%
twin studies
most important evidence
want to know probability are both Sz (concordance rate)
if MZ are more concordant 100% same genes vs DZ 50% shows there’s a gentic factor
Joseph calculated pooled data foun MZ 40% concordance rate vs 7% DZ
recent methodologically sound found lower but still significant %
Gottesman
40 studdies
mz=48% concordance ratevs 17%
suggest genetic factors
ALSO mz twins brought up apart was similar to together
concordance not due to being ttreated similarly within the family
adoption studdies
most unequivocal evidence shows clearest seperation of genetics and evironment
born to 1 or more Sz parent to a ‘normal’ family
if biological= higher rate in adopted vs with normal parents
Tienari et al
try to disentange genetic and environmental factors
finland
164 adoptees with Sz mother
11 diagnosed compared to 4 of control group
show genetic liability to schizophrenia has been ‘decisively confirmed’
- population validity
+large sample
+disentangle role of environment
genetic evaluation
EVALUATION
family studies
supported by family studies
shows a grater risk if familymember also has it
however famly members share an enironment could be this as the cause not the genetics
genetic evaluation
EVALUATION
twin studdies
supported by gottesman
found a higher concordance rate for MZ than DZ
looked at MZ twins brought up a part and still found highre concordance rate
however most also share same environment so we can’t seperate nature vs nurture
genetic evaluation
EVALUATION
adoptive studies
supported by adoption studdies
tienari et al= with Sz mother increased risk
seperate nature and nurtuer, raised outside family see role of genetics
however
not all mothers with Sz have children adopted possible something different with these mothers babies causing the adoptions caused Sz
genetic evaluation
EVALUATION
practical applications
genetic research useful trying to identify gene responsible
Sherrington linked to chromosome 5
hong et al variation TPH gene more common in chinese patients with sz than controls
genetic evaluation
EVALUATION
assumes adoptees are not ‘selectively placed’
joseph= unlikely, ‘because the adoptive parents evidently recieved information about the child’s biological parents, one might wonder who would adopt such a child’
countries like denmark & US, parents informed of genetic background
genetic evaluation
EVALUATION
reductionist
only looks at one factor: genes
utilize the diathesis-stress model= considering why peole develop Sz important not to only consider biological facotr also environmental and stressors
if biologically predisposed, may not develop if they have a ‘good’ environment
