LECTURE VIII Flashcards
CHECK ON LEARNING
a trait influenced by many genes, each having a small but additive effect on phenotype
polygenic trait
what are the characteristics of polygenic traits?
influenced by many genes with an additive effect
inheritance depends on genes
expressed as continuous
frequency distribution follows normal probability curve
for polygenic disorders, if trait determined primarily by environment what does the ratio approach?
what if it is genetic?
0
it approaches 1 or greater
name this type of trait?
a trait whose expression varies gradually between extremes
continuous trait
name this type of trait?
a feature, which at one extreme of expression, manifests as a disorder
quasi continuous trait
term used to describe those genes which in combination, increase the expression of a polygenic trait or disorder?
for example, you 8 genes and when you have adverse alleles present on 5 of those alleles, there is no problem but when 6-7 are added in, you see progressively greater expression of the deleterious trait
genes at risk
term for that point in gene distribution beyond which there is a risk of expressing a disorder?
risk threshold
term for those individuals who are in danger of manifesting quasi continuous traits?
at risk populations
matings between two individuals with genes in common?
effect of this?
consanguinous matings
increases the risk of introducing adverse genes in common and expression of polygenic traits
this type of risk is based on data computed from past experience?
empiric risk
this type of risk based on genes in common and the general population mean?
theoretic risk
the probability that a disorder will reappear in relatives of the affected individual?
based off? relationship number severity sex
reoccurrence risk
term for chemical, environmental, biologic causative agents?
tetragen
Talipes equinovarus or club foot is what kind of disease?
autosomal recessive
