1. LECTURE 5 Genetic Counseling
Medical Genetics
LECTURE 5 Genetic Counseling

2. Objectives To understand the principle steps of genetic counseling.
To know the ethical principles in performing genetic counseling.
To understand unique features of genetic counseling in Arabic/Islamic communities.
To know the sequence of steps for pre-marital screening.

3. Genetic Counselling

4. Genetic Counselling for Mendelian Disorders
Genetic disorders:
Chromosomal
Single gene
Multifactorial
Mitochondrial
Acquired somatic
Only single disorders follow a clearly defined pedigree pattern of inheritance “Mendelian Pattern”.
During genetic counselling it is essential to establish whether or not the disorder is Mendelian and to calculate the precise risk of recurrence.

5. Establishment of Mendelian Inheritance
Pattern of transmission judged from family tree.
For several diseases the family tree may be conclusive even if accurate diagnosis is not made.
For some diseases pedigree pattern is not helpful and only clinical diagnosis is used
For some disorders the pattern looks complicated and the exact diagnosis cannot be made.
More common, a combination of clinical diagnosis and comparable pedigree pattern is required.

6. Essential Components of
Genetic Counselling
Recurrence Risk
History and
pedigree
construction
Follow-up
Confirmatory
diagnosis
Clinical
Examination
Counselling
Calculation of
recurrence risk
- History findings
- Clinical examination findings
- Radiology findings
- Laboratory parameter results
- DNA studies results
- Others
Available
options 5

7. ETHICAL PRINCIPLES Beneficence Autonomy Justice Non-Maleficence
Veracity
Fidelity
المنفعة
الإستقلالية
العدالة
عدم الضرر و الإيذاء
الإخلاص
الصدق و الصحة

8. Genetic Counseling in Achondroplasia
It is inherited in an AD manner.
Homozygous achondroplasia is a lethal condition.
> 80% of achondroplasia cases have parents with normal stature i.e.: de novo (new) gene mutation.
Such parents have a low risk of having another child with achondroplasia.
Prenatal molecular genetic testing is available.
Reem Sallam, MD, PhD

9. Genetic counseling - case
An individual with achondroplasia who has a reproductive partner with normal stature has a 50% risk in each pregnancy of having a child with achondroplasia.
Normal stature (Homozygous)
Achondroplasia (Heterozygous)
Child w/ achondroplasia.
Child w/ normal stature
Reem Sallam, MD, PhD

10. Genetic counseling - case
When both parents have achondroplasia, the risk to their offspring of having normal stature is 25%; of having achondroplasia, 50%; and of having homozygous achondroplasia (a lethal condition), 25%.
Normal stature (Homozygous)
Achondroplasia (Heterozygous)
Homozygous achondroplasia
Child w/ normal stature
Child w/ achondroplasia.
Reem Sallam, MD, PhD

11. Arabic/Islamic Communities
Unique features
Combined family
Living style
Strong Religious
believes
Possibility of
polygamy
Strong link to
traditions and
customs
Large family size
Religious
And cultural
cohesion
High rate of
Consanguineous
marriages
Special views on
Reproductive issues
Artificial
insemination
Family
planning
(IVF) In-vitro
fertilization
Abortion
Adoption
Fetal
rights

13. Premarital Screening Genetic Counseling( *Man - History
(Physical Examination)
Blood
Sample
Genetic Screening (Laboratory)
Carrier
affected
Normal
No Problem from
marriage from
any Women
Safe
Marriage
**Women – (
Physical examination)
any man
Genetic Counseling(
advise no
marriage with carrier or affected)
Not safe

14. Good Luck 
Reem Sallam, MD, PhD