Lecture #63 III

  1. multifactorial modes of inheritance examples:
    • hypertentions
    • diabetes
    • cancer
  2. define multifactorial inheritance
    • complex interaction btwn gene and environemtn 
    • genetic variability with no unifactiral mechanism ( there is no single things that contributes to these inheritance)
    • environement play a BIG roll
  3. quantitative trait
    • polygenic 
    • quantitative trait loci
    • there is always variability
  4. how are quantitative traits measured?
    • a bell curve
    • liability districution 
    • threshold model
  5. what does the threshold model tell you
    if you are below the treshold you have unexpressed genetic varaiation if you are above you have expressed variability
  6. what does a higher threshold mean?
    have less disease because you have to reacha certain amount until it is expressed
  7. what are the neural tube defects
    Spina bifida and anencephaly
  8. what environmental factors can cause neural defects
    folic acid intake
  9. what is the recurrence risk of NTD
    • 1 child= 5%
    • 2 children=10%
    • 3 child=21%
  10. what is the general pop risk for neural tube defects?
  11. empirical risk
    • what has been exactly observed in a population because we cannot calculated multifactorial inheritance 
    • they are disease specific  and based on family studies 
    • specific to population
  12. principles of multi factorial inheritance
    • segregation does not fit mendelian inheritance patterns ( they are more complexed)
    • recurrent risk within a family is larger than general pop
    • inverse relationship btwn recuurence risk and distanc eof family members 
    • risk increase with affected individuals
    • increased roisk comes with increase severity
    • may have a sex bias
  13. cleft palate
    • congenital malformation
    • .1% if non of the parents have this malformation ut risk increases with siblings and 1st and 2nd degress relatives
  14. Pyloric stenosis
    • congenital defect 
    • male biased

    fathers pass on reccurent risk higher to son
  15. what is significant about maternal passing on of the pyloric stenosis  gene
    females have higher threshold and they have greater contribution to creating the gene because there has to be more thing factoringin forthe disease to manifest
  16. Diabetes Type II
    • major risk is family history 
    • second is obesity
  17. cancer genetics
    • there must be genetic changes 
    • rare ocurance
    • genetic predisposition and environemtnal risk
    • uncontrolled cell divison and proliferation that can lead to tumor
  18. protooncogenes
    • normal role if to promote cell proliferation e.g. growth factors, transcription factos, receptor, and signal transduction
    •  when it is mutated it becomes an oncogene which is the bad stuff
  19. oncogenes
    • increase in function mutation 
    • enhance function
  20. tumor suppressors
    • genes involved in suppressing the cycle .g. 
    • p53
  21. retinoblastoma
    • mutationin RB1 gene ( a tumor supressor) 
    • Rb1 has twp alleles and you need mutation in both 
    • two types
  22. two hit hypothesis
    • you need mutation in both alleles of a tumor suppressor in order to progress to cancer phenotype
    • loss of heterocygosity
  23. what mutations cause familial and ovarian cancer
    BRCA1 and BRCA2 genes
  24. what mutation is found in 30% of all cancers?
    Ras mutation
  25. what does p53 normal function
    there to induce apoptosis in a damaged cell
  26. environmental factors that can contribute to cncers
    • smoking 
    • diet 
    • occupation
Card Set
Lecture #63 III
Multifactorial and Complex Diseases - Part 1