2K- Multifactorial Inheritance Flashcards
What is a Multifactorial trait?
Polygenic (the combined effects of multiple genes) trait in which the environment also plays a factor
What is the Threshold of liability?
the point on a liability distribution which has to be crossed in order to express the disease. The lower the threshold, the fewer alleles or environmental factors are needed to develop the disease
What is the Recurrence risk?
The probability that another affected offspring will be produced in a family in which one or more of the children have already been affected
What is a Concordant/discordant trait?
If both twins share a trait, they are concordant, if they do not share the trait they are discordant.
What is Heritability?
Heritability is the % of population variation in a trait that is due to genes
Is the recurrance risk higher or lower if more and 1 family memeber is affected?
higher
What is a proband?
the first person in a pedigree to be identified with the disease
If the expression of the disease in the proband is more severe, is the recurrence risk higher or lower?
Higher
What are the origins of differences between monozygotic twins?
environmental.
What is it called when both twins share a trait?
concordance
What are Phenocopies?
people who have a phenotype but do not carry the known disease-causing mutation.
What are QTL’s?
Quantitative trait loci are stretches of DNA containing or linked to the genes that underlie a quantitative trait.
What is a Genome scan used for?
Markers from the entire human genome are tested for linkage with a disease phenotype.
What is the Affected sib-pair method?
If two siblings are both affected by a genetic disease, we would expect to see increased sharing of marker alleles in the genomic region that contains a susceptibility gene
What is the relationship between the LDL receptor and familial hypercholesterolemia?
it is mutated
What is the genotype of familial hypercholesterolemia?
Autosomal dominant
What is cardiomyopathy?
Abnormality of the heart muscle that leads to inadequate cardiac function
What is mutated to cause cardiomyopathy?
Most commonly mutated genes are those that encode the β-heavy chain, myosin-binding protein C and troponin T
What is dilated cardiomyopathy?
Increased size and impaired contraction of the ventricle causing impaired pumping of the heart.
What is the genotype to cause dilated cardiomyopathy?
It can be autosomal dominant, X-linked or mitochondria
What is the long QT syndrome?
Prolonged cardiac repolarization via blocking potassium channel.
What genetic mutations can cause strokes?
Consequence of several single gene disorder, inherited deficiencies of protein C and S (coagulation inhibitor), mutation in clotting factor V.
What genetic mutations can cause HTN?
Gene that encodes angiotensinogen
What is MODY?
maturity onset diabetes of the young (MODY): Decreased insulin secretion. Occurs before 25 years of age
What is the genotype to cause MODY?
autosomal dominant
What accounts for 50% of the genetic mutations cause of MODY?
50% caused by mutations in the gene the encodes glucokinase (rate limiting enzyme in the conversion of glucose to glucose 6-phoshate in pancreas)
What genetic mutations can cause Alzheimers?
Half of the early onset of AD is attributed to mutation in any of three genes that affect amyloid-β deposition. (PS1, PS2 & APP)
What genetic mutations can cause obesity?
Genes and gene products involved in appetite control and susceptibility to obesity including leptin and its receptor.
What genetic mutations can prevent alcoholism?
Having ALDH2 gene prevents you from becoming an alcoholic. (lol asians)
What genetic mutations can cause schizophrenia and bipolarism?
Genes that encode neurotransmitters, receptors and neurotransmitter-related enzymes.
What genetic mutations can cause ALS?
Superoxide dismutase 1
