This document provides an overview of genetic counselling. It begins by defining genetics and genetic counselling. Genetic counselling is a process that helps people understand medical, psychological and familial implications of genetic contributions to disease. It aims to provide complete information to families and promote informed decisions. Genetic counsellors are health professionals who identify individuals at risk, interpret family histories, and review options. Prenatal diagnosis and screening methods like amniocentesis and ultrasound are discussed. The document concludes by describing the types and steps of genetic counselling.

1. GENETIC
COUNSELLING
CHAITANYA.P
II MDS
Dept of Public Health Dentistry

2. Previous questions
• Genetic counselling (Apr 2010, Oct 2012)
• Genetics and its applications in dentistry (Apr 2011)
2

3. contents
• Introduction
• Genetic counselling
• Genetic screening
• Pedigree charting
• Prenatal diagnosis
• Conclusion
• References
3

4. Genetics
• The term genetics was introduced by Bateson in
1906.It has been derived from Greek word ‘gene’
which means ‘to become’ or ‘to grow into.
4

5. Brief history
Gregor Johann Mendel
( the father of genetics)
5

6. Genetics
• Genetics is defined as a branch of medical
science which concerned with the transmission
of characteristics from parents to offspring.
6
Ref: Jorde Lynn B. Medical Genetics. Mosby, 2005.
King RC, Stansfield WD. Dictionary of Genetics. 3rd edn. Oxford: Oxford
University Press, 1985.

7. General concept
Genetic: Branch of science which studies genes
and the pattern of inheritance of particular diseases
Inheritance: The passing of familial elements from
one generation to the next.
7
Ref: Jorde Lynn B. Medical Genetics. Mosby, 2005.
King RC, Stansfield WD. Dictionary of Genetics. 3rd edn. Oxford: Oxford
University Press, 1985.

8. 8
Gene – Basic unit of genetic information. Genes
determine the inherited characters. It is the
functional subunit of DNA and contain instruction for
making protein.
Chromosomes – storage units of genes. A structure
within the cell that deliver the genetic material as
DNA.
Ref: Jorde Lynn B. Medical Genetics. Mosby, 2005.
King RC, Stansfield WD. Dictionary of Genetics. 3rd edn. Oxford: Oxford
University Press, 1985.

9. 9
DNA - is a nucleic acid that contains the genetic
instructions specifying the biological development of
all cellular forms of life Molecule encodes the
genetic information.
Genome – the collection of genetic information.
Carrier individual- individual who appear normal
but has one copy of mutant gene.
Ref: Jorde Lynn B. Medical Genetics. Mosby, 2005.
King RC, Stansfield WD. Dictionary of Genetics. 3rd edn. Oxford: Oxford
University Press, 1985.

10. 10
 Phenotype: an appearance or characteristic of an
individual, which results from the interaction of the
person’s genetic makeup and his/her environment.
 Genotype: the genetic constitution (genome) of a
cell, an individual or an organism.
Ref: Jorde Lynn B. Medical Genetics. Mosby, 2005.
King RC, Stansfield WD. Dictionary of Genetics. 3rd edn. Oxford: Oxford
University Press, 1985.

11. 11
 Autosomal Dominant: it is one of several ways that
a trait or disorder can be passed down through
families.
(Or)
A gene on one of the non-sex chromosomes that is
always expressed, even if only one copy is present.
 Autosomal recessive: A pattern of inheritance in
which both copies of an autosomal gene must be
abnormal for a genetic condition or disease to occur
Ref: Jorde Lynn B. Medical Genetics. Mosby, 2005.
King RC, Stansfield WD. Dictionary of Genetics. 3rd edn. Oxford: Oxford
University Press, 1985.

12. They are of 3 types:
1.Chromosomal abnormalities
2.Mendelian diseases
3.Multifactorial disorders
CLASSIFICATION OF GENETIC DISORDERS
12

13. 1.CHROMOSOMAL ABNORMALITIES
A. Klinefilter syndrome
B. Turners syndrome.
2.MENDELIAN DISEASES
A. Dominant
B. Recessive
C. Sex linked diseases
13

14. 3.MULTIFACTORIAL DISORDERS
A. Hypertension
B. Diabetes
C. Congenital heart disease
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15. Genetic counselling
15

16. Genetic counselling
Genetic counseling is a process by which patients or
relatives, at risk of an inherited disorder, are
advised of the consequences and nature of the
disorder, the probability of developing or
transmitting it and the options open to them in
management and family planning in order to
prevent or avoid it.
16

17. • Genetic counselling is the process of helping people
understand and adapt to the medical, psychological
and familial implications of genetic contributions to
disease. This process integrates the interpretation of
family and medical histories to assess the chance of
disease occurrence or recurrence, education about
inheritance, testing, management, prevention,
resources and research, and counseling to promote
informed choices and adaptation to the risk or
condition” (NSGC, 2005).National Society of Genetic
Counselors
17

18. Aims of genetic counselling
• The genetic counseling aims to provide the family with
complete and accurate information about genetic
disorders.
1. Promoting informed decisions by involved family
members
2. Clarifying the family’s options available treatment and
prognosis
3. Explaining alternatives to reduce the risk of genetic
disorders
4. Decreasing the incidence of genetic disorders
5. Reducing the impact of the disorders
18

19. WHO ARE GENETIC COUNSELLERS ?
• Postgraduates health professionals with a graduate
diploma or Master's in genetic counseling.
• Experience in the areas of medical genetics and
counseling.
• Identify family at risk, investigates the problems
present in the family, interpret information about the
disorder, analyze inheritance patterns and, risk of re-
occurrence & review available option with the family.
19

20. • Serves as educators and resource people for other
health care professionals and for general public.
• work in administration capacities.
• A team of physician, nurse and social worker who
undergone special training in genetic counseling
• Many engage themselves in research activities
related to the field of medical genetics & genetic
counseling
20

21. WHAT IS THE ROLE OF GENETIC COUNSELLING ?
Genetic Counselors provide genetic information. It is
their counselling skills, including their ability to
empathically connect with their patients that leads to
demands for their skills.
Good Genetic Counselor have many strengths. They
make their clients’ best interest their foremost priority
and are keenly attuned to complex professional and
ethical challenges.
21

22. Genetic Counselor use non-directive counseling
method to provide the best service to those who need
them
To develop a mutual relationship with the client, to
understand her or him, to relieve any psychological
distress, promote a sense of control, and help
find solution to specific problems.
22

23. Assess the client’s strengths, values and needs;
provide an individualization and flexible counseling
style to suite each client’s need and agenda;
develop an awareness of self; and attend to their
own inner life.
23

24. The counselor tends to give advice, make decision,
be coercive, persuasive, influencing, directing and
controlling.
The counselor communicates, enables, explores,
encourages, informs, offers choices, discusses,
promote autonomy, is empathic, non-judgmental,
and respectful of the client.
24

25. PRE-REQUISITES OF GENETIC COUNSELLING IS
• Detailed family history.
• Accurate diagnosis.
• Understanding the medical aspect of the disorder (etiology,
natural history, treatment, prognosis, burden ).
• Understanding the inheritance pattern ( recurrence risk )
• Understanding the psycho-social impact of the information.
• Training / experience in counselling techniques.
• Understanding the concepts of health / disease / healthcare in
the appropriate cultures.
25

26. Function of genetic counselling
session
 Provide information
 Available solution
 Help person to understand and cope with his
condition
 Testing the risk of recurrence
26

27. INDICATIONS FOR GENETIC COUNSELLING
1. Hereditary disease in a patient or family
2. Birth defects
3. Mental retardation
4. Advanced maternal age
5. Early onset of cancer in family
6. Miscarriages
7. Malformations
8. Tendency to develop a neurologic conditions
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28. INFORMATION CONVEYED IN GENETIC COUNSELLING
1. Magnitude of risk of occurrence or recurrence
2. Impact of disease on patient and family
3. Modification of disease impact or risk
4. Anticipated future development
28

29. STEPS OF GENETIC COUNSELLING:
• Diagnosis
• Prognosis
• Treatment
29

30. Genetic counselling ethics
• Respect the right of individual
• Non- directive approach
• Keep privacy of individual and family
• Maintain the communication between counsellor and his
client
30

31. IN SHORT GENETIC COUNSELLING IS
Determine the facts :
• Diagnosis, etiology, and inheritance patterns, prognosis,
natural history, treatment and re-occurrence of risk.
Transmitting the information :
• To those requesting it in a sensitive, culturally appropriate,
understandable way.
Supporting the decision :
• Supporting the decision making process of the couple.
Genetic counselling :
• It is non-directive.
31

32. They are of 2 types:
1.Prospective
2.Retrospective
GENETIC COUNSELLING
32

33. 1. Prospective genetic counselling
This allows for the true prevention of disease.
This approach requires
Identifying heterozygous individuals for any particular
defect by screening
Explaining to them the risk of their having affected children
if they marry another heterozygote for the same gene.
33

34. If heterozygous marriage can be prevented or reduced,
the prospects of giving birth to affected children will
diminish.
EX: Sickle cell anemia
Thalassemia
34

35. 2. Retrospective genetic counselling:
Most genetic counselling at present is retrospective, i.e,
the hereditary disorder has already occurred within the
family .
The methods which could be suggested under retrospective
genetic counselling are:
1.Contraception
2.Pregnancy termination.
35

36. A survey carried out by the WHO showed that
genetic advice was chiefly sought in connection
with congenital abnormalities
• Mental retardation
• Psychiatric illness
• Inborn errors of metabolism
• Premarital advice
36
Ref: Genomics and world health: Report of the advisory committee on
health research, Geneva, WHO (2002).

37. • The WHO recommends the establishment of genetic
counselling centers in sufficient numbers in regions
where infectious disease and nutritional disorders
have been brought under control
• And in areas where genetic disorders have always
constituted a serious public health problem.
37
Ref: Genomics and world health: Report of the advisory committee on
health research, Geneva, WHO (2002).

38. Genetic screening
Definition:
A search in apparently normal population for
individual with abnormal genes which increase their
risk or their offspring of being affected by a disease.
38

39. Types of genetic screening
1. Carrier identification
2. Prenatal diagnosis
3. Newborn screening
4. Forensic screening ( paternity test)
39

40. EARLY DIAGNOSIS AND TREATMENT:
1.DETECTION OF GENETIC CARRIERS :
It is possible to identify the healthy carriers of a
number of genetic disorders, especially the inborn
errors of metabolism.
40

41. 2.PRENATAL DIAGNOSIS:
INDICATIONS:
- Advanced maternal age
- Previous child with chromosome aberration
- Intrauterine growth delay
- Biochemical disorders
- Congenital anomaly
- Screening for neural tube defects and trisomy.
41

42. Pattern of inheritance
• Human cell contain 23 pairs of
chromosomes. 22 pairs autosomal and one
pair sex chromosomes.
• 23chromosomes inherited from mother and
23 chromosomes from father.
• Sex chromosomes: XX for female and XY
for male.
42

43. Genetic pedigree: a diagrammatic representation of
diseases history in a family up to 3rd degree
relative.
43

44. 44

45. Prenatal diagnosis
45
Prenatal diagnosis forms an integral step in genetic
counselling. In fact, for couples at risk of a disorder,
it is desirable to consider, plan and discuss prenatal
diagnosis even before pregnancy. Discussion and
planning beforehand will eliminate hurried
procedures and emotional trauma as well.

46. 46
Let us now consider the following situations that
warrant prenatal diagnosis:
•It is essential for a genetic disorder in which treatment
is either absent or unsatisfactory.
•Disorder in which an accurate prenatal diagnostic test
is possible.
•Risk to the pregnancy is sufficiently high.
•The genetic disorder itself is severe enough to warrant
termination of pregnancy.
•Lastly the termination of pregnancy should be
acceptable to the concerned couple.

47. 47
In the following cases, prenatal diagnosis is a must:
•Maternal age above 35-40 years.
•If one of the parents is a balanced translocation
carrier.
•In case of an autosomal or X-linked recessive
metabolic disorder that is severe but detectable
prenatally.
•Couple already has one child with a neural tube defect

48. Approaches to prenatal diagnosis
48
1. Amniocentesis
2. Chorion villous biopsy
3. Ultrasonography
4. Foetoscopy
5. Foetal blood sampling Prenatal Diagnosis
6. Maternal blood screening
7. Preimplantation diagnosis

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Amniocentesis
• The ideal time to undertake this investigation is
between 14 and 16 weeks when a sufficient amount of
amniotic fluid is available for tapping, without harming
the conceptus.
Procedure:
• Under ultrasound control, placental localisation is done.
• Then under local anaesthesia, the fluid is tapped per
abdomen avoiding injury to the placenta.
• A clear tap, not a blood-stained one, must be ensured.
About 10-20 cc of fluid is taken out and is subjected to
analysis in the laboratory. The cells and fluid are
separated by centrifugation. The cells can be studied
directly or subjected to culture studies for obtaining
foetal karyotype.

50. 50
CHORION VILLOUS BIOPSY
In this procedure, chorionic villi are aspirated with the help of
canula, which is introduced through the cervix uteri. The
procedure is done under ultrasound control. The ideal time
to perform chorion villous sampling (CVS) is 8-10 weeks
period. However, it may be undertaken till almost 12 weeks.

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Merits
1. As compared to amniocentesis, CVS claims an
advantageous position because it is possible at a much
earlier stage of gestation and is easily accepted by
patients.
2. Faster result is possible because chorion villi contain
enough cells under mitosis so as to permit chromosome
analysis without culture.
If the results indicate abnormality in CVS, then termination of
pregnancy is safer and simpler in first trimester than after
amniocentesis (around 18 weeks), which amounts to second
trimester abortion

52. 52
ULTRASONOGRAPHY
The underlying principle in this procedure is that the echoes
generated by the reflection of ultrasound waves are displayed
in one of the two ways:
1. B (brightness) Mode: In this, a cross-section of the anatomy
is created as transducer is moved across an area.
2. Real Time Imaging: In this, repetitive B-mode images are
generated in rapid sequence, allowing appreciation of
motion.
.

53. 53
Basically, ultrasound serves as an ancillary to
amniocentesis. It is helpful in the following ways:
1. Localisation of placenta in amniocentesis or CVS
2. To ascertain gestational age
3. Exclude multiple pregnancy
4. To recognise defects like anencephaly, spina-
bifida, microcephaly, hydrocephalous, etc.
5. Limb defects are also evident on ultrasound

54. 54
FOETOSCOPY
The procedure involves visualisation of foetus using a
fibre optic self-illuminated instrument called foetoscope.
It is inserted in the amniotic cavity under local
anaesthesia. It is usually done around 18-22 weeks of
gestation. With this, one can detect limb malformations,
facial defects (cleft lip, cleft palate, ear defects) or
defects involving the genitals.
The procedure carries a risk of abortion to the tune of
3%-5%. Foetoscopy is useful in obtaining foetoscopic
skin biopsy and foetal blood sampling.

55. 55
FOETAL BLOOD SAMPLING (FBS)
It can be done in two ways:
1. Placental aspiration (indirect tap)
2. Sampling under direct vision
In the former technique, both maternal and foetal blood cells are mixed
need to be separated before sample processing. In the second case,
sample is obtained under direct vision using a foetoscope. Both
techniques carry about 10% risk of abortion. There are number of
conditions in which FBS is needed to make prenatal diagnosis. They are
as follows:
1. Sickle cell disease
2. Thalassaemias
3. Haemophilia A
4. Duchenne muscular dystrophy
5. Immune deficiency disorders

56. MATERNAL SERUM SAMPLE
• Estimation of AFP(alpha-fetoprotein) in maternal serum is
used as a screening test for the detection of neural tube
defect. This test is advocated for all pregnant women,
realising the fact that about 90% babies with a neural tube
defect are born to couples having no family history of such
disorder.
• Maternal serum shows AFP increment during 16-18 weeks of
gestation. Elevated AFP in maternal serum is encountered in
other conditions, e.g. twin pregnancy and missed or threatened
abortion. Having noted elevated AFP, the patient is referred for
ultrasonography and subsequently amniocentesis.
56

57. PREIMPLANTATION DIAGNOSIS
• It involves egg retrieval from the female followed by in vitro
fertilisation (IVF). The fertilised oocyte is allowed to develop
in vitro up to 8 cell stage. A single cell (blastomere) from this
group is removed, its DNA extracted and amplified by PCR
and then analysed to see if there is genetic disorder. If the
analysis does not reveal any defect, the conceptus is
implanted into the mother's womb. In X-linked recessive traits
such as Duchenne muscular dystrophy, the preimplantation
diagnosis is used to determine sex of conceptus (since only
males are affected).
57

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Demerits and Limitations
1. Despite PCR even in the best hands, procedure
using single cell meets a failure rate of 10%-20%.
2. There is a significant risk of false results because of
contamination. Hence, it is safe that an adverse
result of preimplantation diagnosis should be
followed by invasive prenatal diagnosis using CVS
for confirmation.

59. 1.HEALTH PROMOTIONAL MEASURES:
A.EUGENICS:
a. Negative eugenics:
AIM: To reduce the frequency of hereditary disease
and disability in the community to as low as possible
PREVENTIVE AND SOCIAL MEASURES
59

60. B.POSITIVE EUGENICS:
AIM: To improve the genetic composition of the
population by encouraging carriers of desirable
genotypes.
60

61. B.EUTHENICS :
Studies with mentally retarded children indicated that
exposure to environmental stimulation improved their
IQ.
This environmental manipulation is called euthenics.
61

62. OTHER GENETIC PREVENTIVE MEASURES
1.CONSANGUINEOUS MARRIAGES:
When blood relatives marry each other there is
an increased risk in the offspring of traits controlled
by recessive genes and those determined by
polygenes.
EX: Albinism, Alkaptonuria, Phenylketonuria
62

63. An increased risk of premature death is also noted in
such offspring.
Therefore, a lowering of consanguineous marriages
would be advantageous to the health of the
community.
63

64. 2.LATE MARRIAGES:
Trisomy or mongolism is more frequent in children
born of elderly mothers.
Hence early marriage of females is better than late
marriage from the point of view of preventing
mongolism.
64

65. SPECIFIC PROTECTION:
Patients undergoing x-ray examination should be
protected against unnecessary exposure of the
gonads to radiation.
65

66. Rh haemolytic disease of the newborn which is a
genetically determined immunological disorder is
now preventable by immunization by anti D globulin.
66

67. Conclusion
• Many diseases have genetic root
• The genetic screening is an essential issue
in most stages of the life.
• Genetic counselling aim is to bridge the
gap for people between genetic field
complexity and their life.
67

68. Reference
1. Jorde Lynn B. Medical Genetics. Mosby, 2005.
2. King RC, Stansfield WD. Dictionary of Genetics.
3rd edn. Oxford: Oxford University Press, 1985.
3. Harper P. Practical Genetic Counselling. Oxford:
Butterworth Heinemann,1993.
68

69. 69
4. Brock DJH, Rodeck CH, Ferguson Smith MA.
Prenatal Diagnosis and Screening. Edinburgh:
Edinburgh:Churchill Livingstone, 1992.
5. Lilford RJ. Prenatal Diagnosis and Prognosis.
London: Butterworth,1990.
6. K.park’s textbook of preventive and social
medicine. 2015, 23rd edition, bhanot
publishers.
7. Genomics and world health: Report of the
advisory committee on health research,
Geneva,WHO (2002).

70. 70

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