Understanding Understanding Genetic Testing Genetic Testing

Meron Azage, MS, CGCCertified Genetic Counselor

Learning ObjectivesLearning Objectives

Understand the role of the genetic counselor /geneticist

Review components of a genetic counseling session

Review basic genetic concepts Overview of types of genetic tests Review legal/ethical issues

The Role of the Geneticist The Role of the Geneticist • Physical exam • Generate a differential diagnosis• Order appropriate testing • Establish/ confirm a diagnosis–Not always possible

The Role of the Geneticist The Role of the Geneticist • Practice evidence-based medicine

- Recommend screening, management and treatments strategies

• Provide a referral to other specialists

• Apply ethical, legal, and social issue principles•Maintaining patient privacy

What is Genetic What is Genetic Counseling?Counseling?

“Genetic counseling is the process of helping people understand and adapt to the medical, psychological, and familial implications of genetic contributions to disease.”

NSGC 2005

What is Genetic What is Genetic Counseling?Counseling?Genetic counseling services span the life

cycle◦ From preconception counseling to

infertility evaluation◦ Prenatal genetic screening and diagnosis◦ Pediatric –Children with multiple birth defects or

developmental delay–Children with a known genetic conditions

◦ Predisposition evaluation and genetic diagnosis for a growing number of adult onset conditions.

What happens in a genetic What happens in a genetic counseling session?counseling session?Elicit medical history

Take family history

If a diagnosis is known, discuss natural history and inheritance of condition

Discuss relevant genetic testing◦ Offer testing to appropriate family members

Provide resources/ make necessary referrals

PedigreePedigreeDiagram that

records the family history information

An essential component of genetic counseling◦ They provide the

basis for making a diagnosis, determining risk, and assessing the needs for patient education and psychosocial support

Types of Inheritance Types of Inheritance PatternsPatternsChromosomalAutosomal DominantAutosomal RecessiveX-Linked Methylation defect MitochondrialDe NovoMultifactorial

Autosomal DominantAutosomal DominantAutosomal: genetic change is on

the autosomal chromosomesDominant: a change on one of

the chromosomes is enough to cause disease

Affects every generationAffects males and females

equally

AchondroplasiaAchondroplasiaChanges in the FGFR3 gene on

chromosome 4Short stature, enlarged head,

respiratory problems, ear infections

AchondroplasiaAchondroplasia

Types of Genetic TestingTypes of Genetic TestingClinical

◦Carrier testing◦Preimplantation testing◦Prenatal testing◦Newborn screening◦Diagnostic testing◦Predictive and presymptomatic

testingResearch

Clinical whole exome Clinical whole exome sequencingsequencingThe human exome is made up of all

the exons (functionally important parts of the gene translated into proteins).

The exome is less than 3% of the entire genome.

In the exome, about 85% of disease causing changes/ mutations happen.

This test looks at over 20,000 protein-coding genes.

What is the exome?What is the exome?

Genetic Counseling Code of Genetic Counseling Code of Ethics Ethics The counselor-client relationship

is based on values of care and respect for the client’s autonomy, individuality, welfare, and freedom.

Informed Consent Informed Consent Who is consenting?Are all the options presented?Does the patient understand the

options?Is the patient capable of giving

consent?

Genetic DiscriminationGenetic DiscriminationGINA is a law. Genetic testing results cannot be

used to discriminate by health insurance or employers◦Does not cover life, long term care or

disability insurance

ResourcesResourcesAmerican Board of Genetic Counselors

◦ Abgc.netNational Society of Genetic Counselors

◦ www.nsgc.orgNational Institute of Health – Genetic

Disorders◦ http://health.nih.gov/topic/

GeneticDisordersMy family health portrait

◦ https://familyhistory.hhs.gov/fhh-web/home.action

QUESTIONS ?QUESTIONS ?