Genetic Counseling By: Cary Edmondson ISAT 351 April 19, 1999

Genetic Counseling n What is Genetic Counseling? n Diagnosis n Risk Calculation n Communication n Personal Experience

What is Genetic Counseling? n 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 n Diagnosis is the most important step!! n Diagnosis includes: –Taking a family history –Medical Examination –Follow-up investigations

Family History n The patient must be comfortable. n Determine the relationship, sex, age, and carrier status of all 1st degree relatives n The conditions of births (stillbirth, miscarriage) n Consanguinity n Nonpaternity n Ethnic Background

Medical Examination n Genetic material is collected n Photographs are taken n Physical Measurements n Amniocentesis n The Genetic Counselor does not give this exam.

Follow-up Investigations n Genetic screening and tests are done. n Informed consent is given to talk to other family members. n Feedback n Literature n Support Groups

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

Mode of Inheritance n Autosomal Dominant –affected person has 1 dominant mutant allele and 1 recessive normal allele, heterozygous n Autosomal Recessive –both parents are heterozygous with the same recessive mutant allele n Sex linked disorder –X-linked and Y-linked

Probability n Law of Addition = mutually exclusive n Law of Multiplication = independent n Bayes’ Theorem –determines the overall event or outcome by considering all possibilities –Final Result = Posterior probability that someone is a carrier

Risk Calculation n The counselor must practice caution. n The patient must understand the result of a risk calculation.

Communication n Nondirectiveness and Autonomy n Informed Consent and Confidentiality n Social and Cultural Differences n Nonpaternity

Nondirectiveness and Autonomy n The counselor must not force their beliefs upon the patient. n The patient must make their own decisions.

Informed Consent and Confidentiality n The counselor must provide a confidential and comfortable environment for the patient. n The counselor must have the consent of the patient before any tests are done or information is discussed.

Social and Cultural Differences n The counselor must be aware of the patients social and cultural background. n This will allow the counselor to work from the patients point of view and not their own.

Nonpaternity n A genetic disorder cannot be properly diagnosed if the biological parents are not known. n The counselor must be able to identify these situations.

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