Transcript Genetics and family planning

Matthew Bower, MS
University of Minnesota Ataxia Center
ATAXIA-GENETICS AND FAMILY PLANNING
DISCLAIMER
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The information provided by speakers in any
presentation made as part of the 2012 NAF Annual
Membership Meeting is for informational use only.
NAF encourages all attendees to consult with their
primary care provider, neurologist, or other health care
provider about any advice, exercise, therapies,
medication, treatment, nutritional supplement, or
regimen that may have been mentioned as part of any
presentation.
Products or services mentioned during these
presentations does not imply endorsement by NAF.
PRESENTER DISCLOSURES
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Matt Bower, MS, CGC
The following personal financial relationships
with commercial interests relevant to this
presentation existed during the past 12
months:
No relationships to disclose or list
TAKE-HOME POINTS:

Ataxia genetics are too complicated for a 30
minute talk!
I
will be speaking in broad generalizations
 Consult with your physician or genetic counselor
about your specific questions
TAKE HOME POINTS

Plan ahead
 Many
testing options require advance knowledge of
your genetic status
TAKE HOME POINTS

Family planning decisions are personal
decisions- there is no “right” answer.
GENETICS REVIEW- DOMINANT INHERITANCE
SCA1-36 (and counting!)
These men are
both affected with
ataxia
GENETICS REVIEW- DOMINANT INHERITANCE
SCA1-36 (and counting!)
Each of these siblings has an
independent 50% risk
GENETICS REVIEW- RECESSIVE INHERITANCE

Friedreich, AOA1, AOA2, AT, and
others
These two sibilngs
have ataxia
GENETICS REVIEW- RECESSIVE INHERITANCE
Both parents are
carriers
GENETICS REVIEW- RECESSIVE INHERITANCE
These two siblings have a 2/3
(67%) carrier risk
GENETICS REVIEW- RECESSIVE INHERITANCE
Carrier risk for spouses depends on how
common the ataxia is in the general
population
STEP 1- WHAT KIND OF ATAXIA IS IN MY FAMILY?

Diagnostic testing- Testing someone with
symptoms to figure out the type of ataxia in
your family.
 This
person may be you (if you have symptoms), or
it may be another family member.
 Genetic testing is only accurate if the type of ataxia
in the family is known.
 Important to obtain actual test results, if possible.
STEP 2- WHAT IS MY GENETIC STATUS?

In order to determine if your children may be at
risk, it may be important to determine your own
genetic status
 Dominant
 If
ataxias
you have symptoms, you could have diagnostic testing.
 If you are asymptomatic, you could have predictive
testing.
STEP 2- WHAT IS MY GENETIC STATUS?

In order to determine if your children may be at
risk, it may be important to determine your own
genetic status
 Recessive
 Affected
ataxias
with the familial ataxia-diagnostic testing
 Biological relatives of affected individuals (carrier testing)
 Non-biological relatives of affected individuals (i.e.
people who marry into the family) carrier testing
STEP 3- WHAT ARE RISKS TO FUTURE
CHILDREN?
 Dominant
ataxias
 If
you have the ataxia gene, your child will have a 50%
risk (regardless of whether it is a boy or girl)
 If you did not inherit the ataxia gene, then your children
are not at risk (i.e. does not skip generations).
 Recessive
 If
ataxias
both parents are carriers, the risk to each child is 25%
(regardless of whether it is a boy or girl)
STEP 4- WHAT ARE MY OPTIONS?
Having children without any genetic testing
 Adoption / Foster parenting
 Pregnancy with prenatal diagnosis
 In vitro pregnancy with donor egg
 donor sperm
 In vitro pregnancy with genetic testing (preimplantation genetic diagnosis)

PRENATAL DIAGNOSIS
Definition- Genetic testing done during a
pregnancy to determine if a fetus is affected
with the familial ataxia
 Two procedures are available:

 Chorionic
villus sampling (CVS)
 Amniocentesis
AMNIOCENTESIS
• Amniotic fluid is removed using a thin needle.
• Cells from amniotic fluid can be tested for the familial
ataxia
• Generally done after 15 weeks gestation
• Small risk of miscarriage (< 0.5%)
CVS
• Generally done 10-13
weeks gestation
• Not as widely available as
amniocentesis
• Risk of miscarriage varies
from center to centergenerally <1%
INTRAUTERINE INSEMINATION WITH DONOR
SPERM
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If the father is affected with a dominant ataxia,
or a carrier of a recessive ataxia, patients can
utilize a donor sperm sample
 Known
unaffected relative
 Anonymous donor

Does not require IVF procedures
IN-VITRO FERTILIZATION

Sperm and egg are mixed in a petri dish to
create embryos.
IN-VITRO FERTILIZATION WITH DONOR EGG
IVF (all by itself) does not alter the risk for
ataxia in children.
 If the mother is either affected with the ataxia,
or is a carrier, couples can do in-vitro
fertilization using an egg from a healthy donor.
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PRE-IMPLANTATION GENETIC DIAGNOSIS
Embryos created through IVF
 One cell from each embryo is tested to
determine if the embryo is “affected” with the
familial ataxia.
 Only “unaffected” embryos are transferred to
the uterus.

PRE-IMPLANTATION GENETIC DIAGNOSIS (PGD)
PRE-IMPLANTATION GENETIC DIAGNOSIS (PGD)
Braude, P., et al., Preimplantation genetic diagnosis, Nature Reviews
Genetics 3, 941–955
NON-INVASIVE PRENATAL DIAGNOSIS
Fetal DNA is known to be in mother’s blood
during pregnancy
 Tests have recently been developed to
diagnose some specific fetal conditions from a
maternal blood draw

 No
risk of miscarriage
 Not yet available for conditions like ataxia.
SUMMARY- WHAT ARE MY OPTIONS?
Having children without any genetic testing
 Adoption / Foster parenting
 Pregnancy with prenatal diagnosis
 In vitro pregnancy with donor egg
 donor sperm
 In vitro pregnancy with genetic testing (preimplantation genetic diagnosis)

STEP 5- WHAT IS RIGHT FOR ME?
Does my future child’s ataxia status have any
bearing on my decision to have children?
 Importance of being the biological
mother/father
 Financial- will insurance cover the costs of
procedures?
 Are there medical risks with some of these
technologies
 Emotional investment with in-vitro fertilization
technologies.
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THANK YOU
MY DEFINITION OF FAMILY PLANNING