LECTURE 5 Genetic Counseling Medical Genetics LECTURE 5 Genetic Counseling

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.

Genetic Counselling

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.

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.

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

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

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

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

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

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

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

Good Luck  Reem Sallam, MD, PhD