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Author6 Posts
  #1

What is anticipation .Give examples ?
What is pleiotropy.Give example ?
what is incomplete and complete penetrance.Give examples ?
what is imprinting.Give examples ?




  #2

No body answered it sad

I know its boring but if we discuss it will become easy :idea:


  #3

smiling face ok, let's take it apart . . .

Anticipation:
-inheritance in which the most recent generations of a pedigree develop a disease at an earlier age or w/ greater severity than in earlier generations
-can be due to gradual expansion of trinucleotide repeat.
-trinucleotide repeat expands and expands and mutations get bigger and bigger per generation
-ex: Huntington's, Fragile X, Myotonic dystrophy

Pleiotropy:
-when 1 disease causing mutation affects lots of different parts of body and multiple organ systems
-ex: Marfan syndrome (just think, whole lot of stuff happens because defect in just one gene, fibrillin)

Incomplete Penetrance:
- some people who have the disease genotypically, don't show it phenotypicall, meaning no symptoms noted related to disease
-the person inherits the mutation, but doesn't show it
ex: this can be in case

Complete penetrance:
-person has the disease and shows symptoms relating to it
-in other words, disease is what it genotypically shows.
ex: likewise, can be any disease


  #4

imprinting is genes are transcriptionally active only when transmitted by one of the two sexes
-prader -willi syndrom
-angelman syndrom


  #5

thanks to both of you...

Another example of pleiotopy ( multiple effects caused by a single mutation) is osteogenesis imperfecta

What is locus heterogeneity ??


  #6

locus heterogeneity is when the same disease phenotype can be caused by mutations in different loci.e.g., in osteogenesis imperfecta,defect in type-1 collagen may be coded by either chromosome7 or 17,but one cant distinguish between disease caused by either of the two.





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