Molecular Genetics 2 Flashcards
Function of G72?
Oxidize serine - an activator of glutamate transmission via modulatory site on NMDA receptor.
How does G72 lead to schizophrenia?
Inadequate DAOA function may lead to problems in modulating glutamate signal in areas of brain like prefrontal cortex.
G72 my be involved in maintaining neural structure.
What do antidepressants do to BDNF?
Increased central BDNF in animals
Which chromosome is DISC1 (disrupted in schizophrenia 1) found?
1q
What is DISC1 associated with?
Microtubules
Mice: abnormal neuronal migration and dendritic organization in delevoping cerebral cortex.
How does DISC1 play a role in mood regulation?
Ineracts with phosphodiesterase 4B
Which three genes are associated with other behavioural phenotypes, which interact with environment to increase risk of major depression?
5HTT
Which three genes are associated with other behavioural phenotypes, which interact with environment to increase risk of major antisocial personality disorder?
MAOA
Which three genes are associated with other behavioural phenotypes, which interact with environment to increase risk of schizophrenia?
COMT
What is dysbindin involved in?
Formation of synaptic structures
What is neuregulin involved in?
Neuronal migration and genesis of glial cells and subsequent myelination of neurons by these cells
What is GRK3 involved in?
Only animal studies
Down-regulation of G-protein coupled receptors - associated with bipolar
Mutations leading to Alzheimers?
Amyloid precursor protein and presenilin 1 and 2 for as much as 50% of familiar alzheimers before 60 years og age.
Where is amyloid precursor protein?
Chr 21
Where is presenilin 1?
Chr 14
Where is presenilin 2?
Crr 1
Which genetic factor has highest attributable risk for Alzheimers?
Apolipoprotein E
Where is apolipoprotein E?
Chromosome 19q with 3 codominant alleles, differing by single base substitutions in coding region.
Which alleles are over and under-represented in apolipoprotein E?
Ancestral allele, 3, is over represented
Allele 2 is under-represnted
Mean age of onset of Alzheimers in those with allele 4 apolipoprotein E homozygous?
2 decades earlier
Also increases risk in nonwhite populations
More in females
Which protein is associated with both Downs and Alzheimers?
Chr 21 - mutant amyloid precursor protein
Risk of Alzheimers in first degree relatives and controls
15-19%
5% (controls)
DZ concordance rates of Alzheimers
40%
MZ concordance rates for Alzheimers
84%
What are the three different syndromes of frontotemporal lobar degenaration?
Frontotemporal dementia
Progressive non-fluent aphasia
Semantic dementia
Genes in frontotemporal lobar degeneration
Some patients show tau protein
Familial cases - MAPT on chromosome 17q21
Which gene has been located in tau-negative patients with frontotemporal lobar degenaration?
Progranulin gene on chromosome 17q21
What is progranulin?
Growth factor involved in round repair and inflammation by activating signalling cascades in cell cycle.
Tumrigenesis.
How are Lewy bodies formed?
Synucleinopathies - synuclein molecules aggregate in presynaptic terminals
Gene position of PARk 1 and 4
5Q21 gene
Protein made from PARK 1 and 4
Alpha-synuclein
Features of PARK 1, 4 inheritance in Parkinsons
Onset in 40s
Inheritance of PARk 1 and 4
Dominant inheritance
Pathology in PARK 1 and 4 Parkinsons
Nigral degenaration with Lewy bodies
Position of gene in PARk 2
6q25
Protein made by PARK 2
Parkin gene
Inheritance of PARK 2
Recessive
Pathology of PARk 2
Nigral degeneration w/o Lewy Bodies
Onset of PARK 2 Parkinsons
40-60
Position of gene of PARK 8
12 cen (pericentromeric) LRRK2 gene
Inheritance of PARK 8
Dominant
Onset of PARK 8 Parkinsons
60
Pathology of PARk 8 Parkinsons
Variable alpha-synuclein and tau pathology
Location of gene of PARk 6
1p35-37 -PTEN-Induced
Kinase (PINK1) in mitochonrdia
Inheritance of PARk 6
Autosomal recessive
Onset of Parkinsons in PARk 6
30-40
Location of gene of PARk 7
1p38 DJ-1
Inheritance of PARK 7
Autosomal recessive
Onset of Parkinsons in PARk 7
Autosomal recessive
What is alpha-synuclein?
Protein expressed in brain, role in learning, synaptic plasticity, vesicle dynamics and dopamine synthesis
Recurrence rate in siblings of austic children
2-8%
MZ twin concordance rate of autism
60%
DZ twin concordance rate for autism?
0%
Heritability of autism?
90%
Which chromosomes are implicated in autism?
2
7
15
Possible inheritance patterns of autism?
AR
Sex-specific modifications
Which gene disorder is associated with autism?
Fragile X - 16% of males are autistic
Risk to first degree relatives of ADHD
15-60%
Heritability of ADHD
70-80%
Risk of ADHD in terms of gender?
Higher in males
Largest factor for personality disorder?
Nearly 50%:
Nonshared, person-specific environmental variation
Which PD has the highest heritability?
Antisocial - 60-70%
Which feature has high heritability in BPD?
Emotional dysregulation
Lifetime prevalence of panic disorder?
4.7%
Heritability of panic disorder
0.43
Which type of social phobia does not show familial transmission
Non-generalised, discrete social phobia
Which phobias are 3-4 times more common in first degree relatives?
Specific phobias
What do twin studies show re phobias?
Individual-specific environmental influences more important for simple phobies
Risk of alcoholism in families
4-6x general population
Genetic factors for alcohlism
Variants in GABRA2 on chromosome 4p - also related to impulse control
ADH4 - associated with earlier onset of drinking
A1 allele of DRD2
Which enzyme breaks down EtOH?
Alcohol dehydrogenase
What is EtOH broken down into?
Acetaldehyde and then aldehyde dehydrogenase.
What increases genetic risk of OCD?
Increased severity and chronicity
Risk of OCD to first degree relatives if onset <18?
10-35%
MZ Twin concordance of OCD?
53-87%
DZ twin concordance of OCD?
22-47%
Tests for genetic testing?
Direct
Gene tracking
Prenatal identification
What is direct testing?
Sample is tested for a certain genotype.
Only one person is tested.
What is gene tracking?
Family members are tested to discover if suspected patient has inherited high risk chromosome from heterozygous parent.
What does gene tracking look for?
Segregation of chromosome within a family.
What is prenatal identification?
Test of fetus to identify suspected genotype.