Home >> Flashcards >> Biology >> C1-51 Multifactorial Inheritance And Common Diseases
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Term
Multifactorial inheritance, disease types:
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Definition
1.Certain congenital malformations: CL(P), NTD, CHD, pyloric stenosis, etc.
2. “Common diseases,” usually of adult onset:
ischaemic heart disease, hypertension, manic depression, schizophrenia, Alzheimer disease, etc. Also HLA-related autoimmune diseases: type I diabetes, rheumatoid arthritis, etc.
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Term
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Definition
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is based on the variance of the trait in the population studied, and is symbolized as H2 or h2.
H2 and h2 are numbers that vary between 0 and 1.
H2 = Vg / Vt
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Term
The threshold model for malformations |
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Definition
•A set of polygenes and environmental factors contribute to the developmental process (closure of the neural tube or of the palatal shelves, etc.)
•The malformation occurs when a sufficient number of mutant polygenic alleles and harmful environmental factors reach a threshold.
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Term
Multifactorial inheritance in congenital malformations; summary |
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Definition
•Threshold rates are determined empirically for each disease.
•Occurrence risks vary with populations.
•Recurrence risk is higher when:
- the proband is more severely affected
- the proband is of the seldom affected sex
- more than one family member is affected
- there is a consanguineous marriage
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Definition
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