 Parents of a 4 year old child were referred for  genetic study. The child had “jaundice” with fluid in his tummy  for o...
 How come their child has “inherited disease  when they are healthy? What could have gone “wrong” ? What tests will gua...
 Patterns of inheritance will easily explain this... But there are spontaneous mutations and there is a role of environ...
   Malfunctioning of a gene/s                                 5
 It is a functional area on a chromosome which is  made up of various nucleotides, which will  manufacture various protei...
Gene       7
8
 A car engine has several parts If one part is defective,     the engine may not work,     works defectively or     i...
10
   Chromosomal abnormalities or mutation or aberration    are according to their structural and numerical changes    they...
   Gene mutations have varying effects on health, depending on where    they occur and whether they alter the function of...
 Normal function Partially normal function Totally non-functional        Lethal        Compatible with life in a limi...
   One which is frequently seen in a given disease    due to genetic defect                                              ...
If a Bajaj scooter is not working,most commonly you have to tilt it !!But there could be other reasonsalso, the uncommon c...
Bajaj scooter and Honda may not startfor entirely different reasonsIndians may have different mutationsresponsible for Wil...
   More mutations we test, more chances are that    we will be more confident in your predictions   So we have to know m...
   We can’t proceed further without knowing what    was the disease and what was the mutation    responsible for their fi...
   All we can offer them is the common mutation    tests for commonly occurring genetically    inherited liver diseases....
On the other hand.... Had we known the disease and the mutation in  the proband, then certainly we can test the fetus  fo...
   If we don’t know what happened to the proband,    we can’t do much in the next pregnancy                              ...
 Carrier testing before conception Best example is screening for DMD                                      22
   Testing the fertilized embryo for genetic dosing.                                                        23
 By amniotic fluid at 16 weeks; and Chorion Villous Biopsy at 12 weeks Triple marker test                              ...
   By New Born Screening (NBS)                                  25
26
 Some disorders that "run in families" can be traced to  shared environmental exposures rather than any inherited  suscep...
 Gene can go wrong in various ways. This is called  mutation. Different races have different mutations, some  common and...
29
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Introduction to genetics   final
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Introduction to genetics final

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Introduction to genetics final

  1. 1.  Parents of a 4 year old child were referred for genetic study. The child had “jaundice” with fluid in his tummy for over a year and died because of the same. Parents are planning second pregnancy and are worried that the second pregnancy might also be affected as they were told that their first child could have died because of some “inherited” disease. 2
  2. 2.  How come their child has “inherited disease when they are healthy? What could have gone “wrong” ? What tests will guarantee that their next child will be healthy? How and where the tests will be done? 3
  3. 3.  Patterns of inheritance will easily explain this... But there are spontaneous mutations and there is a role of environmental factors also, e.g. tobacco 4
  4. 4.  Malfunctioning of a gene/s 5
  5. 5.  It is a functional area on a chromosome which is made up of various nucleotides, which will manufacture various proteins, that will carry out various bodily functions. If it works well, our body works well If it is not working well, a genetic defect, then our body may have some malfunction. 6
  6. 6. Gene 7
  7. 7. 8
  8. 8.  A car engine has several parts If one part is defective,  the engine may not work,  works defectively or  it may breakdown half way through Same thing will happen, when a gene has some defective parts 9
  9. 9. 10
  10. 10.  Chromosomal abnormalities or mutation or aberration are according to their structural and numerical changes they termed as Structural abnormalities Numerical abnormalities 11
  11. 11.  Gene mutations have varying effects on health, depending on where they occur and whether they alter the function of essential proteins. The types of mutations include: Missense mutation Nonsense mutation Insertion Deletion Duplication Repeat expansion 12
  12. 12.  Normal function Partially normal function Totally non-functional  Lethal  Compatible with life in a limited or compromised way 13
  13. 13.  One which is frequently seen in a given disease due to genetic defect 14
  14. 14. If a Bajaj scooter is not working,most commonly you have to tilt it !!But there could be other reasonsalso, the uncommon causes 15
  15. 15. Bajaj scooter and Honda may not startfor entirely different reasonsIndians may have different mutationsresponsible for Wilson’s disease thanCaucasians 16
  16. 16.  More mutations we test, more chances are that we will be more confident in your predictions So we have to know mutations in our population, otherwise we may keep making mistakes. 17
  17. 17.  We can’t proceed further without knowing what was the disease and what was the mutation responsible for their first child’s, “the proband’s”, death 18
  18. 18.  All we can offer them is the common mutation tests for commonly occurring genetically inherited liver diseases. As we may understand, this may lead to lots of problems. 19
  19. 19. On the other hand.... Had we known the disease and the mutation in the proband, then certainly we can test the fetus for that particular mutation and reasonably certainly counsel the parents. 20
  20. 20.  If we don’t know what happened to the proband, we can’t do much in the next pregnancy 21
  21. 21.  Carrier testing before conception Best example is screening for DMD 22
  22. 22.  Testing the fertilized embryo for genetic dosing. 23
  23. 23.  By amniotic fluid at 16 weeks; and Chorion Villous Biopsy at 12 weeks Triple marker test 24
  24. 24.  By New Born Screening (NBS) 25
  25. 25. 26
  26. 26.  Some disorders that "run in families" can be traced to shared environmental exposures rather than any inherited susceptibility. In addition, some mutations detected by a positive test may never lead to disease. Furthermore, because existing tests look only for the more common mutations in a gene, but some disease- causing mutations may escape detection. 27
  27. 27.  Gene can go wrong in various ways. This is called mutation. Different races have different mutations, some common and some uncommon and what applies in Caucasians may not apply in India. Looking for mutation in sibling without knowing mutation in the proband is no..no.. But a reliably diagnosed mutation could be the most accurate way of diagnosing a genetic diseases. 28
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