Complex Patterns of Inheritance

Question 1

Continuous variation

Answer 1

Phenotypic distribution of a complex trait that can’t be placed in discrete classes, but ranges from one extreme to the other in an overlapping fashion
- ex, Human height have very short and very tall phenotypes and also everything in between

Question 2

Discontinuous variation

Answer 2

Where individuals fall into a number of discrete phenotypic classes, for a complex trait, that can’t be measured across a complete range
-ex, individuals who are predisposed to having Schizophrenia

Question 3

Regression to the Mean

Answer 3

Distribution of polygenic traits throughout the population, following a bell-curved shape.
-The complex trait sees regression to the mean when two individuals with opposite extreme phenotypes and said genotype, produces offsprings with intermediate phenotypes of the parents.
-This phenomenon might reduce the phenotypic variation to some extent but will increase the genetic variation in the population.

Question 4

Liability/Threshold model

Answer 4

A method used to study and explain the development of complex traits in a specific population.
- Risk for developing complex traits can be estimated in a population at a specific time, based on the polygenic risk score inferred from additively contributing genes.
-This can be estimated for individuals within the population of related individuals (i.e., family), the more closely related an individual is to an affected individual, the more likely they are to share alleles contributing to the disorder, thereby increasing their chance of risk
-When the liability line, provided by the risk score, is crossed, this indicates the development of the disorder.
-The risk score calculated within the general population is called the population incidence.
-The risk score calculated in the family is called the familial incidence.

Question 5

Complex trait

Answer 5

A trait controlled by multiple genes and environmental influences, and exhibiting a large variety of phenotypes.
- complex traits are only understood when all genetic and environmental components and mechanisms of action are fully identified and measured.