Key word defs Flashcards
Genome
All the DNA
Gene
Sequence of DNA which codes for proteins, not all DNA is genes there is DNA between them which has other functions
Single nucelotide polymorphisms
small differences in dna sequence where a single base is altered
DNA sequence overlap
the degree of similarity between peoples DNA dependent on relatedness
Copy number variants
Lesions where parts of chromosomes are either missing or duplicated. They are always heterozygous as being on both chromosomes isn’t compatible with life. Inheritted or de novo.
Cross fostering
Having two batches of babies and swapping the mothers babies so they raise their non biological offspring, used to find out the genetic contribution of traits
Shared environment
A confound in family and twin studies, we tend to live with our first degree relatives making it hard to seperate what we have got from them genetically and what we have learned from them envoironmentally
equal environments assumption
assuming that twins share the exact same environment either outside the womb (MZ twins are treated differently than DZ) or inutero (degree of amniotic sac sharing)
genetic determinism
we are entirely predisposed to be how we are based on our genes, dangerous as can be used to justify inequality and eugenics
Blank slate ideology
we have no psychologically innate traits we are solely our experience
Passive gene environment correlation
parents who transmit genes to their children also help to create the environment they are reared in
evocative gene environment correlation
environments people experience are in part a function of how others react to their genetically influenced behaviour
active gene environment correlation
individuals actively construct their environments by selecting experiences that reinforce or complement their inherited abilities, dispositions and interests`
G×E Contextual Triggering
genetic effects are triggered or amplified by exposure to high risk environment e.g. MAO-A gene
- G×E Social Context as Social Control
the existence of environments that suppress the expression of genetic effects. Typically, this suppression occurs because the environment limits individual choice.
Heritability
Estimate of the overall genetic contribution of a condition.
Ascertainment bias
certain features impact on the incidence of a certain trait/ disorder e.g. parents of boys are more likely to go to the gp about certain symptoms and therefore the boys are more likely to get a diagnosis/ help, so is it true that boys have higher risk etc or just that there is ascertainment bias
Linkage mapping
Look at the incidence of a given trait/ disorder in an extended family and use DNA markers to narrow down the bits of the genome which are transmitted within the condition across family members
Mendelian disorders
Fully penetrant, a type of genetic disorder primarily resulting due to alterations in one gene
Penetrance
how damaging it is
Non mendelian
multigenic conditions
Association studies
‘Is there a reliable (statistically significant) enrichment of a given genetic variant (i.e. difference in DNA sequence) in cases (people with the disorder) than in an independent sample of control (healthy) subjects?
candidate led studies
are variants in my favourite gene suspect associated with disorder <– pick a gene and then test, hypothesise
GWAS
genome wide association studies- start with no hypothesis or expected gene. screen whole genome and look for differences between cases and controls
DNA chips
microscope slides that are printed with thousands of tiny spots in defined positions, with each spot containing a known DNA sequence or gene
enrichment
SNP allele frequency, highly enriched for risk alleles
polygenic risk
common risk SNPs that, singly, are not very damaging but when accumulated could in some individuals provide significant risk.
allele frequency
how common in the population they are
next generation sequencing
significantly better resolution than ‘DNA chip’ technology, therefore good for revealing rare variants
rare variants
alternative forms of a gene that are present with a minor allele frequency (MAF) of less than 1%
ultra rare variants
dURVs—damaging variants unique to a single individual
Fecundicity
how many (fertile) offspring you have. e.g. Are high penetrant genetic variants rare in the population because they are damaging to fecundity, whereas low penetrant SNP variants are common because they are less damaging to fecundity?
Missing heritability
When you look at percentage of risk that is estimated by genetics it does not match the molecular genetic work which estimates that actual estimates of genetic contribution to a disorder. e.g. for highly heritable schizophrenia (60-80% heritability estimate) all the current known risk variants (not only those that satisfy genome-wide significance) amount to about 30% of the heritability.
Pleiotropy
Influence multiple characteristics, 22q11.2 deletion is a risk gene for heart probs and autism and schizophrenia
induced pluripotent stem cells
Now possible to ‘reprogramme’ human somatic cells (e.g. skin or hair or blood cells) taken from a patient suffering from a brain disorder back to a pluripotent stem cell state to form induced Pluripotent Stem Cells (iPSC, only called tis when they have been reprogrammed) from which it is possible to make neurons … and ‘mini brains (organoids whereby iPSC derived neurones self organise’. we can model brain disorders in a dish
Genetic liability
to have the same genetic liability is meaning they maintain the same genome e.g. ipscs have the same genetic liability as the OG cells
Allelic pleiotropy
a subtype of genic pleiotropy, occurs when the same gene variant influences multiple traits
Mediated pleiotropy
Mediated pleiotropy occurs when an allele influences two traits, but its effects on one are secondary to more direct effects on the other.
Pseudo-pleiotropy
Pseudo-pleiotropy can arise as a result of imprecision in gene mapping, wherein two phenotypes are influenced by different genes in close proximity or poor study design
Transciption
is the process of reading the DNA and creating RNA
Translation
ranslation is synthesising proteins from this RNA.
Epigenetics
Long lasting, stable regulation of gene expression (activity), marks upon the genes which create further variation
Specialisation
totipotent cells developing to be for a specific function, which genes will be expressed
Maintenance of cells identity
Once cells have differentiated you need to maintain that cells identity as it replicates into daughter cells.
Altering the transcriptional capability of DNA
Altering the ability of enzymes to access the DNA, a form of epigenetics
DNA methylation
Chemical modification of a base, adding a methyl group which typically will then mean that that gene will not be transcribed, it is silenced.
Histones
proteins around which DNA is bound. Histones are the main component of chromatin. Chromatin compacts and provides stability and structure to the DNA.
X-inactivation
Balances X-gene expression in females (XX) with males (XY)
Writers
Enzymes that add epigenetic marks, they are factors which regulate epigenetic state
Erasers
Enzymes that remove epigenetic marks, they are factors which regulate epigenetic state
Readers
Readers – proteins that read (or bind) an epigenetic mark, they are factors which regulate epigenetic state
Neurogenic cell
brain cell
Kleefstra or 9q34 syndrome
Low muscle tone - hypotonia, seizures, developmental delay, mutation in EHMT1, an epigenetic writer
Rett syndrome
ASD like symptoms, only affects biological features, loss of speech, mutation on X chromosome;an epigenetic reader
Angelman syndrome and Prader Willi
neurodevelopmental disorders caused by the same mutation to 15q11-q13.which disorder is dependent on whether the deletion occurs on the maternal or paternal inheritted chromosome.
AS caused by de novo loss of maternal gene expression due to (epi)genetic mutations affecting the imprinted gene cluster on chromosome 15q11-q13
PWS caused by de novo loss of paternal gene expression due to (epi)genetic mutations affecting the imprinted gene cluster on chromosome 15q11-q13
parthonogenic embryos
created in a lab, where the embryo had two copies of the paternal gene not one of each and these were not viable so there must be something that distinguishes maternal and paternal copies they cannot be equivalent.
Social insects
Social means function in massive groups almost as one organism, e.g. ants
CpG islands
regions of the genome that contain a large number of CpG dinucleotide repeats. In mammals, the majority of DNA-methylation happens here.
Gametogenesis
the process in which cells undergo meiosis to form gametes
Eusocial
living in a cooperative group in which usually one female and several males are reproductively active and the nonbreeding individuals care for the young or protect and provide for the group, e.g. ants
Transgenerational epigenetic marks
epigenetic marks which transmit from parent to offspring
Assisted Reproductive Technologies and epigenetics
in vitro culture (taking out an egg and then putting a sperm and putting it in a dish) of embryos disrupts developmentally programmed epigenetic processes? this is due to the artificial environment the culture happens in compared to when it is done naturally in the body. e.g the increased rate of AS in ART babies, ALL due to epimutations not genomic mutation
epi-pharmaceutical intervention
administration of drugs which alter dna methylation.
like Histone deacetylase inhibitors (chemical compounds that inhibit histone deacetylases.) which increases acetylation of histones to the low licked pups lead to Increased H3K9 acetylation at GR promoter, Decreased DNA methylation, Increased GR expression- making them more like the highly cared for pups.
DNA methylome
methylation across the whole genome
epigenetic clock theory of ageing
Numerous studies have shown that epigenetic age—an individual’s degree of aging based on patterns of DNA methylation—can be computed and is associated with an array of factors including diet, lifestyle, genetics, and disease
Epigenome-Wide Association Studies
Genome wide screens of epigenetic change associated with a disease phenotype
Transgenerational epigenetic inheritance
environmentally mediated epigenetic & phenotypic changes transmitted across generations
- behavioural inheritance not fixed in germ line
- germline changes, changing epigenetic status of germ cells via maternal or paternal
Sex differences
variations in biology between men and women
Gender differences
Differences between men and women bith in terms of biology and self representation as shaped by the environment
egalitarian socieities
socieities with equal treatment of the sexes
sexually dimorphic brain regions
systematic difference in form between individual’s brains of different sex in the same species
WEIRD populations
Western, Educated, Industrialized, Rich and Democratic populations
psuedo genes
nonfunctional segments of DNA that resemble functional genes. Most arise as superfluous copies of functional genes
SRY
Sex-determining Region on Y- a gene, the testis-determining gene
can influence brain development/function indirectly via gonadal hormones
SRY expression during 6-8 weeks- embryogenesis causes bipotential gonads to differentiate into testes
Extreme male brain theory of autism
- Men systemise whereas empathise
- Exaggeration of male phenotype
- People with autism may be exposed in utero to high levels of androgens
Gynandromorphic birds
male one side and female the other , both in appearance and in the brain BUT very cell in its body is surrounded by the same level of hormones so must be something acting other than hormones.
Karyotype
chromosome
- Haplogroup
A haplogroup is a genetic population group of people who share a common ancestor on the patriline or the matriline, A haplotype refers to a set of DNA variants along a single chromosome that tend to be inherited together
Deletion mapping
Deletion mapping allows you to see precisely which region is responsible for the phenotypical deficit, it means you can find a candidate gene region.
Turner syndrome
20% higher in adhd likelihood and higher autism rates. a condition that affects only females, results when one of the X chromosomes (sex chromosomes) is missing or partially missing. Turner syndrome can cause a variety of medical and developmental problems, including short height, failure of the ovaries to develop and heart defects
superhapolotype
a chromosome where all super versions of a gene end up on one x chromosome. E.G. all the high IQ genes end up on one chromosome
transient sex difference
reversable sex difference
masculinisation / feminisation
any change that makes an animal more like typical males or females. Masculinization and defeminization are not synonymous because the differentiation of tissues subserving feminine functions can be independent of differentiation of tissues subserving masculine functions. For example, some treatments may masculinize, but not defeminize.
Gonadectomy
an operation to remove the gonads. These are the organs that develop into either ovaries or testes
Baby blues
Affects up to 50% of women after birth, mood swings, crying , overwhelm, short period
Post partum depression
afters 10% to 40% and require treatmnent, symptoms of baby blues but also possible thoughts of harming self or baby
puerperal psychosis
post partum psychosis, 1-2 in 1000 women with onset within a couple days/ weeks of birth, hallucinations/delusions, cogntive distortion
puerperal psychosis
post partum psychosis, 1-2 in 1000 women with onset within a couple days/ weeks of birth, hallucinations/delusions, cogntive distortion
dissociability
un associated with
primiparity
A medical term used to refer to a condition or state in which a woman is bearing a child for the first time
nanopore sequencing
take a string of dna and pass it through a protein channel and everytime a different base passes through it causes an electrical current and by measuring the current we can determine which base it is therefore the order of the bases. doesnt need sample amplification or chemical labelling
Saviour siblings
people having a second child in the hopes theyll be a genetic match so they can donate bone marrow to save the affected child
mendelian randomisation
Mendelian randomization is a method of using measured variation in genes of known function to examine the causal effect of a modifiable exposure on disease in observational studies.
nutrigenomics
genetically informed diets
CRISPR
Clustered Regularly-Interspaced Short Palindromic Repeats
RNA-guided genome editing tool based around components of prokaryotic ‘immune system’
Tissue (e.g. stem cells from blood) can be removed from patient, gene defect corrected, and tissue re-implanted Again, limited utility for complex polygenic disorders with neurobiological basis. More useful for monogenic conditions
You could possibly rescue fragile x or use for cystic fibrosis
Optogenetics
Get a gene which encodes a protein which is responsive to certain wavelength of light and stick that gene into the bit of the brain you are interested in and then shine alight using an implanted canular into the brain and when you shine that light it cause the proteins to activate the neurons in that bit of brain circuitry. Means you can easily activate a brain region which could tell us about disorder brain dysfunction
DREADDs
Modulation of neural circuits (not single genes) via introduction of genes for non-endogenous drug receptors
Receptor binding can cause increased (Gs or Gq-DREADD) or decreased (Gi/o-DREADD) cellular activity
Chemicals can switch on or off bis of the brain. Bc the brain is highly vascularised the chemicals get dep into the brain easier than light in opotgenics. So greater degree of control
D2C genetic testing
Genome analysis, not sequencing, for cheap and it provides risk liklihood of different conditions. arguement of whether it is a consumer appliance or a medical tool, so should it be avaliable to the public the way it is
genetic counselling
Genetic counseling gives you information about how genetic conditions might affect you or your family.
protection of freedoms act
*People not charged/acquitted of minor offences will have records deleted
People not charged/acquitted of serious offences will have records deleted 3 years after arrest
People suspected of terrorism offences will have records deleted 3 years after arrest
XYY males
previously thought males with this genotype were at an increased liklihood for violence and crime and so was used as a criminal defence. Cannot currently be used as a defence due to multifacetted nature of violence
Organophosphates
a chemical in sheep dip which acts as acetylcholinesterase inhibitors and some people with a certain genotype (* Paraoxonase1 (PON1) ) are more vulnerable to its effects so farmers could do genetics testing to see if they shouldn’t be working in this area.
mentally precocious youth
IQ> 150
g factor
general cognitive ability
HCNEs- highly conserved CNEs
functional conserved non-coding (for proteins) elements
APOE4
the high risk alzhiemers gene
