Multifactorial diseases Flashcards
define medelian
obeys Mendel’s laws of segregation – dominant, recessive, X-linked.-single gene
define complex
inherited but non-Mendelian component
define polygenic
the result of the action of multiple genes.
define multifactorial
the result of multiple factors, usually including both genetic and environmental factors.
what equation is used to determine the relative risk of second sibling
relative risk of the sibling/ relative risk of the general population.
doe multifactorial diseases have a genetic component.
Yes
1- relative risk of second sibling
2-Twin studies- genetic characters should have a higher concordance (risk) in monozygotic twins compared to dizygotic twins because they have the same genes and similar environment
what are the major problems in twin studies to look for genetic components affecting multifactorial conditions.
Monozygotic twins
- Assumption that the degree of environmental sharing is the same for MZ twins- can have different prenatal environments.
- diamniotic monozygotics.
Dyzygotic twins
-1 in 10 has undergone a blood transfusion from their dizygotic pair during pregnancy.
what do adoptive studies show
show how much difference the environment can make on multifactorial conditions (have the same environment at their adoptive parents, however not the same genotype)
Do gene involvement in multifactorial conditions have a additive effect
Yes.
more genes involved the more higher the risk is.
what shaped curve does the normal distribution of common diseases form
Gaussian curve.
what congenital malformations show multifactorial inheritance.
cleft lip/palate, congenital hip dislocation, congenital heart defects, neural tube defects, pyloric stenosis, talipes
what acquired diseases of childhood and adult hood show multifactorial inheritance
asthma, autism, cancer, diabetes mellitus, epilepsy, glaucoma, hypertension, inflammatory bowel disease (Crohn disease), ischaemic heart disease & stroke, bipolar disorder, multiple sclerosis, Parkinson disease, psoriasis, rheumatoid arthritis, schizophrenia
What does a association study show.
relate variation in human DNA sequence with a disease or trait
What markers are commonly tested in association studies
SNP’s
what does a higher number of SNP’s in a person mean
They are more likely to have a disease of trait.
what does the mapping of medelian conditions reveal.
Medelian-rare but have severe effect (in terms of symptoms)
what does the mapping of multifactorial conditions reveal.
frequent in both control and case but more common in patients (E.g. SNP)
what does SNP stand for
single nucleotide polymorphism
what effect do SNP’s have on diseases
They are usually present but create not effect on phenotype. Rarely they can cause a disease trait.
Common usually binary (relating to or associated with)
How are SNP’s tested for
SNP’s hybridised to oligonucleotide probes on a glass film.
The probe will show whether you have both the same bases on the 2 chromosomes or 2 different.
How are SNP’s inherited and how are the linked to increasing the risk of causing disease.
SNP’ are inherited in the DNA which surrounds the mutation.
SNP’s are not the cause of the mutation, however they are passed on alongside the mutation due to their proximity.
Over generations the increased frequency of SNP’s can result in reaching a significance level at which the SNP increases the relative suceptibitiy of each disease.
What method/ tool is used to determine medelian inheritance
family tree.
In Alzheimer’s disease you do not inherit the condition what do you inherit
susceptibility
what are some of the main genes which predispose you to developing Alzheimer’s
Preseniln 1, presenilin -encode new transmembrane aspartyl proteases with g-secreatase activity responsible for proteolytics cleavage of amyloid beta A4 precursor protein (APP)
what apolipoprotein in involved in protecting and increasing risk of developing Alzheimer’s.
apolipoproetien E.
which haplotype of apolipoprotein confers increased susceptibility to alziehmers.
E4 haplotype (arg and arg)
which haplotype of apolipoprotein confers protective effect to alziehmers.
E2 haplotype (cys and cys)
Is alzihemers affected by the environment
Yes
more you use your brain onset of alzeihimers is delayed.
what multifactorial condition does the early deposition of drusen in the eye lead to
age- related macular degeneration
what environment al risk factor increases the risk of developing age related macular degeneration
smoking - main
light exposure
what genes increase the susceptibility of developing age related macular degeneration
CFH (1q), ARMS2 (10q)
