Multifactoral Inheritance

Question 1

What is multi factorial inheritance?

Answer 1

The type of hereditary pattern seen when there is more than one genetic factor involved and, sometimes, when there are also environmental factors participating in the causation of a condition

Question 2

Give some examples of multi factorial inheritance

Answer 2

Normal traits- Height, blood pressure and intelligence
Acquired onset- Asthma, diabetes and epilepsy

Question 3

What are the 2 types of multi factorial inheritance?

Answer 3

Continuous- No distinct phenotype (height)
Discontinuous- distinct phenotype (diabetes mellitus)

Question 4

Why is Type 2 diabetes multi factorial?

Answer 4

It is due to inheritance of susceptibility genes and environmental factors such as obesity

Question 5

What is a susceptibility gene?

Answer 5

Genes that make an individual susceptible to developing a disease

Question 6

Describe and explain polygenic inheritance

Answer 6

A phenotype determined by 2 or more genes at different loci with each gene exerting and additive effect

Question 7

What are polygenes?

Answer 7

Genes that make small cumulative contribution to a polygenic trait, i.e no genes are dominant or recessive
This is because if many genes are involved its more difficult to predict the phenotype

Question 8

What is concordance?

Answer 8

When both twins separated at birth and grow up in different families develop a disorder
This shows that the genetic contribution of a trait is strong

Question 9

What is discordance?

Answer 9

When twins are separated at birth and grow up n different families and only one twin shows a certain trait, this mans tat the gene contribution is not strong

Question 10

How is multi factorial inheritance studied?

Answer 10

Identical twin studies are carried out because they have identical genotypes
However identical twins are not 100% concordant, which indicates there are non-genetic factors involved