Post on 20-Sep-2020
DEMYSTIFYING GENETIC COUNSELING
AND PRENATAL TESTING/SCREENING
Patti Furman, MPH, CGC
Board Certified Genetic Counselor
OBJECTIVES
Review definition of genetic counseling
Review basic inheritance patterns
Understand common indications for genetic
counseling
Update on prenatal testing/screening options
Resources
Q & A
WHAT IS GENETIC COUNSELING?
“a communication process which deals with the
human problems associated with the
occurrence, or risk of occurrence, of a genetic
disorder in a family”
Ad Hoc Committee on Genetic Counseling
American Society of Human Genetics
GENETIC COUNSELING
Process helps the individual/family to:
Understand the genetics involved in their situation
Comprehend medical facts
Understand alternatives for dealing with risk
Choose a course of action which is appropriate in view of their risk, family goals, ethical and religious standards
Make the best possible adjustment to that disorder and/or to the risk of recurrence of that disorder
WHO ARE GENETIC COUNSELORS?
Health care professionals that
work as a member of a
multidisciplinary team
Specialized masters degree
Experience in medical genetics
and counseling
Risk Assessment
Education
Support/Advocacy
Facilitate Decision Making
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Genetics Review
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DOWN SYNDROME
Increased risk with advanced
maternal age but can happen
at any age!
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Examples: Cystic Fibrosis, Sickle Cell Anemia, Rare Metabolic Disorders
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Examples: Marfan Syndrome, Achondroplasia, Huntington Disease
XX
XY XX
XY
Examples: Fragile X Muscular Dystrophy
XY
XY
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Examples: spina bifida, heart defects, cleft lip/palate
PRENATAL SCREENING IN LOW RISK
POPULATION
Scenario: 25 year old
First pregnancy
Negative Family History
GOALS OF PRENATAL SCREENING AND
TESTING
“There are no perfect human specimens - we are all
genetically flawed in some way.”- F.Collins
Help parents learn what they need to know about the
health of their unborn child to help them make
informed decisions for themselves and their family
within the context of their own value system.
WHY IS PRENATAL TESTING
OFFERED?
In 2007 the American Congress of Obstetricians and
Gynecologists (ACOG) issued a statement
recommending that prenatal testing for conditions such
as Down syndrome be offered to all women who come
for prenatal care before 20 weeks of pregnancy,
regardless of the mother’s age.
Screening tests do not give
yes or no answer
False pos & false neg
Results are either a
numerical value or risk
estimate
1 in #
Low or high risk
Requires follow up testing
to confirm
Non-invasive/no risk
Diagnostic tests
“gold standard”
Results ~ 100%
accuracy
Invasive: slight risk of
miscarriage
SCREENING TESTS VS DIAGNOSTIC
TESTS
EXAMPLES OF PRENATAL SCREENING
First trimester screen
Second trimester screen
MSAFP testing
Non-invasive prenatal testing (NIPT/NIPS)
Ultrasound
Carrier testing
HOW IS FIRST TRIMESTER
SCREENING DONE? (FTS)
FTS is performed between 11 and 13.6 weeks of pregnancy, and involves an ultrasound and a small amount of the mother’s blood.
The ultrasound is performed to measure the space behind the baby’s neck called the nuchal translucency (NT). The mother’s blood is collected to measure a naturally occurring pregnancy hormone and pregnancy related protein.
The ultrasound information and mother’s blood sample are sent to the laboratory for risk estimate.
Detects ~ 85-90% Down syndrome
Detects ~ 90% trisomy 18/13
WHAT IS SECOND TRIMESTER
SCREENING?
Second Trimester Screening is performed between 16-20
weeks of pregnancy using a small sample of the
mother’s blood.
Second trimester screening provides risk estimates for
trisomy 21, trisomy 18, and open neural tube defects
(spina bifida).
This is commonly known as Quad or Penta screen
ONTD (OPEN NEURAL TUBE DEFECTS)
Spina bifida/anencephaly
1-2/1000 births
In-utero repair possible
ULTRASOUND
20 weeks ideal for anatomy
Can identify many major anomalies
Spina bifida
Congenital heart defects
Limb defects
Soft signs
Fluid in kidneys
Choroid plexus cysts: benign spots in brain
Intracardiac echogenic foci: spots in the heart muscle
Normal ultrasound does not mean normal baby!
CARRIER SCREENING
We are all carriers of something!
Only when two carriers of the same gene have a baby
there is chance for the disorder
Cystic fibrosis
ACOG 2011 All women should be offered
screening regardless of ethnicity
Sickle cell disease
Rare diseases
UNIVERSAL CARRIER TESTING
Panel of 80-100 genes
Many rare and serious conditions on the
panel
If parents are carriers of same condition
may do prenatal testing
REASONS TO REFER FOR PRENATAL
GENETIC COUNSELING
Advanced maternal age >35
Abnormal screening test
Abnormal Ultrasound
finding(s)
Abnormal genetic test results
Family history of genetic
disorder/ birth defect
Previous child/pregnancy
genetic disorder / birth
defect
Multiple pregnancy loss
Medication exposure
Is my
pregnancy
at risk?
My friend said
she had this
test….
What options
do I have? What about before
we get pregnant?
How do I
decide?
I don’t want
that needle
test!
Family trees reveal many interesting facts
CASE SCENARIO
CONTINUED
Pregnant woman age 39
“By the way my daughter has developmental
delay and my son was born with a heart
problem”
“ We’ve also got sickle cell disease and some
cancer in my family”
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Pedigree: Maternal Age 39
recessive multifactorial ?
WHAT IS NON-INVASIVE
PRENATAL TESTING/SCREENING?
Non-Invasive Prenatal Test or Non Invasive Prenatal
Screen (NIPT/NIPS) is an advanced screening test
that measures genetic material (DNA) from a pregnant
woman’s blood to determine if the pregnancy has too
many or too few copies of certain chromosomes.
This blood test is offered after 10 weeks of gestation
Currently screens for trisomy 13, 18, 21 and X/Y Detection rate for tri 21 and 18 is ~99% Recommended for high risk pregnancies Diagnostic Testing If Positive NIPT!
Diagnostic Testing
• Amniocentesis
–>15 weeks: 1/300 risk miscarriage
–Chromosome analysis
•Other genetic tests if indicated
– AFP (for spina bifida)
–~ 100% accuracy
Diagnostic Testing
• CVS
–10-13 weeks <1% risk for miscarriage
–Chromosome analysis
•Other genetic tests if indicated
–~100% accuracy
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What about my daughter with developmental disability?
PEDIATRIC/ADULT GENETIC
COUNSELING
Reasons to see a pediatric GC and Medical Geneticist Developmental disability Autism spectrum disorder Dysmorphic features Birth defects Family history Abnormal growth pattern Behavior problems Neurological issues
For the CHILD
Find appropriate medical and non-medical therapies
Screen for associated complications or disabilities before symptoms are seen
Avoid unnecessary testing and evaluation
Help with educational planning (immediate and long term)
Start physical therapy, occupational therapy, and/or speech therapy, as soon as possible if needed.
Early diagnosis and recognition may impact the long-term outcome for children with many conditions.
For the PARENTS
Provide information about the cause and treatment
Offer support, guidance and an outline of what to expect
Provides sense of control
Enables referrals to appropriate medical and social service agencies, support groups
Help with decisions about long-term care planning (insurance, education, contraception, adult living)
Provides accurate reproductive options
Learn about opportunities for education, advocacy and research studies
BENEFITS OF A GENETIC EVALUATION
AND DIAGNOSIS
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Do I need to worry about breast and ovarian cancer?
Refer to cancer genetic counselor!
SUMMARY
Many options for prenatal screening/testing
Family history is important for recurrence risk counseling
and other referrals
Genetic counselors are available to help answer
questions, offer education, support and “non-
directive” guidance
CHW’s are important part in allaying
fears/misconceptions about genetic testing!
HOW CAN I FIND A GENETIC COUNSELOR?
National Society of Genetic Counselors
www.nsgc.org
American Board of Genetic Counselors
www.abgc.net
LOCAL RESOURCES
TCH Center for Children and Women: GP and SW pediatric medical home and pilot OB medical home for TCHP patients
Genetic Counselor: Patti Furman 832-828-1696
Ben Taub Genetics
Genetic Nurse: Wanda Dosal
TCH Pediatric Genetics: 832-822-4283
Baylor Adult Genetics: 713-798-7820
Baylor Prenatal/Houston Perinatal Associates: 713-799-1930
Pavilion For Women: 832-826-7500
Baylor Breast Center: Cathy Sullivan 713-798-9098