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Understanding Genetic
Testing
Meron Azage, MS, CGC
Certified Genetic Counselor
Learning 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
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Physical exam
Generate a differential diagnosis
Order appropriate testing
Establish/ confirm a diagnosis
– Not always possible
The Role of the Geneticist
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Practice evidence-based medicine
- Recommend screening, management and
treatments strategies
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Provide a referral to other specialists
Apply ethical, legal, and social issue
principles
• Maintaining patient privacy
What is Genetic 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 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 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
Pedigree

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Diagram 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 Patterns
Chromosomal
 Autosomal Dominant
 Autosomal Recessive
 X-Linked
 Methylation defect
 Mitochondrial
 De Novo
 Multifactorial

Autosomal Dominant
Autosomal: genetic change is on the
autosomal chromosomes
 Dominant: a change on one of the
chromosomes is enough to cause disease
 Affects every generation
 Affects males and females equally

Achondroplasia
Changes in the FGFR3 gene on
chromosome 4
 Short stature, enlarged head, respiratory
problems, ear infections

Achondroplasia
Types of Genetic Testing

Clinical
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Carrier testing
Preimplantation testing
Prenatal testing
Newborn screening
Diagnostic testing
Predictive and presymptomatic testing
Research
Clinical whole exome sequencing
The 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 proteincoding genes.

What is the exome?
Genetic Counseling Code of Ethics

The counselor-client relationship is based
on values of care and respect for the
client’s autonomy, individuality, welfare,
and freedom.
Informed Consent
Who is consenting?
 Are all the options presented?
 Does the patient understand the options?
 Is the patient capable of giving consent?

Genetic Discrimination
GINA 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
Resources
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American Board of Genetic Counselors
◦ Abgc.net
National Society of Genetic Counselors
◦ www.nsgc.org
National Institute of Health – Genetic Disorders
◦ http://health.nih.gov/topic/GeneticDisorders
My family health portrait
◦ https://familyhistory.hhs.gov/fhh-web/home.action
QUESTIONS ?