Genetics Week 14 Flashcards
What is the definition of multi factorial traits
Traits influenced by multiple genes and environmental factors
What are multifactoral traits referred to as
Polygenic if only genetic factors are involved
How are Quantitive traits measured
As a continuous numerical scale
What dos each gene in a multifatorial trait still follow?
Segregation and independent assortment
What is the concept of the threshold model
-That some diseases do not follow a normal (bell shape )distribution
-They appear either present or absent but do not follow single-gene inheritance patterns
Diseases follow a liability threshold model where :
- People with a low liability(risk factor) are unlikely to develop the disease
-people with high liability are more likely to develop the disease - The diseases is only expressed once a threshold is crossed
What type of recurrence risk does single-gene diseases have
- Predictable recurrence risks
What type of recurrence risk does multifactorial diseases contain and why
- Complex risks due to unknown contributing genes, parental allelic constitution and environmental factors
What are empirical risks used for
- Multifactorial diseases based on direct observation and family studies
What does recurrence risk estimation involve
- examining families with an affected child(proband) and calculating the percentage of affected relatives
Name the types of Neural Tube defects
- Anencephaly
-spina Bifida
-encephalocele
What is the most common type of Neural tube defect
- Spina Bifida
What is the cause of Neural Tube defects
Failure of the neural tubes closing during the fourth week of gestation
How can neural tube defects be detected
- Ultrasoud and a-fetoprotein( AFP) levels in maternal serum or amniotic fluid
How can neural tube defects be prevented
- By taking folic acid supplementation before and during early pregnancy
- Genetic variation in Folic acid metabolism
