Genetic Counseling

By: Cary Edmondson

ISAT 351

April 19, 1999

Genetic Counseling

What is Genetic Counseling? Diagnosis Risk Calculation Communication Personal Experience

What is Genetic Counseling?

American Society of Human Genetics 1975 – Communication process dealing with genetic disorders that

involves an attempt by trained persons to help an individual or family:

• 1) comprehend medical facts• 2) understand why the disease is hereditary and risk of

recurrence• 3) understand their options and alternatives• 4) choose a course of action• 5) make an adjustment to the disorder

Diagnosis

Diagnosis is the most important step!!

Diagnosis includes:

– Taking a family history

– Medical Examination

– Follow-up investigations

Family History

The patient must be comfortable. Determine the relationship, sex, age, and

carrier status of all 1st degree relatives The conditions of births (stillbirth, miscarriage) Consanguinity Nonpaternity Ethnic Background

Medical Examination

Genetic material is collected Photographs are taken Physical Measurements Amniocentesis The Genetic Counselor does not give

this exam.

Follow-up Investigations

Genetic screening and tests are done. Informed consent is given to talk to

other family members. Feedback Literature Support Groups

Risk Calculation

Risk calculations deal with:– Mode of Inheritance– Probability– Bayes’ Theorem

Mode of Inheritance

Autosomal Dominant– affected person has 1 dominant mutant allele and

1 recessive normal allele, heterozygous Autosomal Recessive

– both parents are heterozygous with the same recessive mutant allele

Sex linked disorder– X-linked and Y-linked

Probability

Law of Addition = mutually exclusive Law of Multiplication = independent Bayes’ Theorem

– determines the overall event or outcome by considering all possibilities

– Final Result = Posterior probability that someone is a carrier

Risk Calculation

The counselor must practice caution.

The patient must understand the result of a risk calculation.

Communication

Nondirectiveness and Autonomy

Informed Consent and Confidentiality

Social and Cultural Differences

Nonpaternity

Nondirectiveness and Autonomy

The counselor must not force their beliefs upon the patient.

The patient must make their own decisions.

Informed Consent andConfidentiality

The counselor must provide a confidential and comfortable environment for the patient.

The counselor must have the consent of the patient before any tests are done or information is discussed.

Social and Cultural Differences

The counselor must be aware of the patients social and cultural background.

This will allow the counselor to work from the patients point of view and not their own.

Nonpaternity

A genetic disorder cannot be properly diagnosed if the biological parents are not known.

The counselor must be able to identify these situations.

Personal Experience

Confidentiality Family and personal medical history Discussion of possible outcomes Medical Examination--Amniocentesis Follow-up