Genetic Inheritance Session 23 Flashcards
1
Q
What are multifactorial traits ?
A
- Traits that are controlled by polygenes subject to environmental influences.
2
Q
What is a Pleiotropy ?
A
- A single mutant gene affects two or more distinct and seemingly unrelated traits
3
Q
What is penetrance used for ?
A
- it is used to describe whether or not there is a clinical expression of the genotype in the individual.
For example: If a mutation in the gene responsible for a particular autosomal dominant disorder has 95% penetrance, then 95% of those with the mutation will develop the disease while the 5% will not
4
Q
Describe expressivity
A
- it describes the differences observed in the clinical phenotype between the two individual with the same genotype.
5
Q
What is the most common test to determine color blindness ?
A
- Ishira test
6
Q
What are examples of X-linked recessive disorders ?
A
- Color blindness
- Duchenne muscular dystrophy
- Hemophilia
7
Q
What is Duchenne muscular dystrophy and what is it caused by ?
A
- It is the degeneration of the muscles, individuals pass away by 20-25 years old.
- Caused by the absence of a protein called dystrophin, which causes calcium to leak into the cell which stimulates an enzyme that dissolves muscle fibres
8
Q
What are the different types of Hemophilia and how do you treat it ?
A
- Hemophilia A : absence of clotting factor VIII
- Hemophilia B : absence of clotting factor IX
- Hemorrhages can be stopped with transfusions of fresh blood or the missing clotting protein
9
Q
What is an example of X linked dominant disorder ?
A
- Fragile X syndrome
