2.  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

3.  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

4.  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

5.  Malfunctioning of a gene/s
5

6.  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.
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7. Gene
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8. 8

9.  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

10. 10

11.  Chromosomal abnormalities or mutation or aberration
are according to their structural and numerical changes
they termed as
 Structural abnormalities
 Numerical abnormalities
11

12.  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

13.  Normal function
 Partially normal function
 Totally non-functional
 Lethal
 Compatible with life in a limited or compromised way
13

14.  One which is frequently seen in a given disease
due to genetic defect
14

15. If a Bajaj scooter is not working,
most commonly you have to tilt it !!
But there could be other reasons
also, the uncommon causes 15

16. Bajaj scooter and Honda may not start
for entirely different reasons
Indians may have different mutations
responsible for Wilson’s disease than
Caucasians 16

17.  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

18.  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

19.  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

20. 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

21.  If we don’t know what happened to the proband,
we can’t do much in the next pregnancy
21

22.  Carrier testing before conception
 Best example is screening for DMD
22

23.  Testing the fertilized embryo for genetic dosing.
23

24.  By amniotic fluid at 16 weeks; and
 Chorion Villous Biopsy at 12 weeks
 Triple marker test
24

25.  By New Born Screening (NBS)
25

26. 26

27.  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

28.  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.
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29. 29

30. 30