Transcript Day 17: Reproduction Powerpoint

Reproductive Technology
Learning Objectives
By the end of this class you should
understand:

Causes of infertility in men and women

The different types of assisted reproductive technologies

The primary sources of ethical issues surrounding ART

The technique and concerns for genetic screening


The potential for treatments such as gene therapy and cord
blood
The process and benefits of genetic counseling
Fertility


Not all people are
naturally able to
produce children
Infertility is
approximately
equally common in
men and women

Increases with age
in women
Types of Infertility


Primary infertility is
inability to have a first
child
Secondary infertility
is when a couple has
already had one or
more children but is
having difficulty
having more

Focus is on primary
infertility here
Female Infertility Causes

Problems with hormonal levels


Ovarian problems


Since hormones are required for ovulation
Since ovaries produce eggs
Oviduct/Uterine problems

Since this is where the fetus is fertilized/grown
Female Infertility
Male Infertility Causes

Low sperm count


Low sperm motility


May be partially genetic in origin
Genetic infertility


Fewer sperm than typical
Mutations on Y chromosome in particular
No sperm produced

Kilefelter's syndrome, infection, damage to testes,
hormonal imbalance including steroids, etc
Male Infertility
Assisted Reproductive Technologies



Refers to all techniques
to improve fertility
Primary techniques
include artificial
insemination and in vitro
fertilization
The exact choice
depends on which parent
has the problem and
what kind
Artificial Insemination


Artificial Insemination uses
some means of artificially
creating a fertilization event
Only viable if the mother's
uterus is healthy

Major use is when father is
infertile or mother wants to
become a single parent

May also be applied after IVF
In Vitro Fertilization

Creation of a fertilization
event outside a person's
body


“In vitro” means “In glass”
referring to a test tube
May apply when female
is infertile or male sperm
has motility problems

Must be implanted into
healthy uterus, either the
mother's or a surrogate
Sperm Injection


A particular type of in
vitro fertilization is
called intracytoplasmic
sperm injection
Performed by injecting a
single sperm cell
directly into an egg


Typically for sperm count
or motility problems
Egg is then implanted
as normal
Egg Acquisition

For in vitro fertilization to
work, eggs must be
removed from the mother


If the mother's ovaries are
not functioning (e.g.
Turner Syndrome, etc),
eggs must be collected
from a donor
Mother's eggs are
typically removed via
surgery

Extra eggs can be stored
IVF Implantation


Fertilized eggs are
incubated for several
weeks before implantation
Implantation is
accomplished via catheter


The same kind of catheter
used for chorionic villus
sampling
Leftover eggs may be
harvested for embryonic
stem cells or discarded
IVF Analogues

Gamete intrafallopian transfer (GIFT)


Sperm is placed directly into woman's oviduct
during ovulation
Zygote intrafallopian transfer (ZIFT)

Fertilization accomplished via IVF then implanted
directly into mother through surgery
Surrogacy

An arrangement can be
made with another woman if
the mother's uterus cannot
sustain a baby


May be artificially inseminated
or have the embryo
implanted, for different types
of surrogacy
This has the potential to
introduce complications

Not legal in every state
Risks of ART

As with any pregnancy,
individual chances of
fertilization and implantation are
not 100%


Even fertile couples must typically
“try” for months
To minimize costs, multiple
fertilizations and implantations
are carried out with each
procedure

Half of all IVF births are multiple
births
Major Risks of IVF

Multiple births


Ectopic pregnancy


Premature birth, low birth
weight, etc
Implantation in fallopian tube,
extremely dangerous
Increased risk of
chromosomal deletions using
ICSI
Genetic Screening

Genetic screening is testing for a disease
without prior indication that the disease is
present



Predictive instead of diagnostic
The entirety of the US performs newborn
screening for PKU (most common metabolic
disorder)
Some states test only a few diseases, some
test many
Newborn Screening

California's full list of screening targets:
http://www.cdph.ca.gov/programs/nbs/Documents
/NBS-DisordersDetectable011312.pdf

This is relatively uncontroversial and in general
a very good preventative step
Preimplantation Genetic Diagnosis

When creating embryos
via IVF, a single cell
from the blastomere
(ball of cells) can be
removed and tested for
genetic disorders


Called preimplantation
genetic diagnosis (PGD)
Typically performed
when child is at risk for
a genetic disorder
PGD Controversy



These parents had a daughter
with Falconi anemia
They had a son who they
screened with PGD to ensure he
would not have the same disorder
The son's cord blood was used to
treat the daughter's disorder

Was he grown specifically to be a
donor for the daughter?

Is that legit?
Cord Blood


Blood from the umbilical
cord of a baby contains
adult stem cells just like
red bone marrow
Some hospitals save it
for research and
transfusion

No database for it so it's
more hit-or-miss
Gene Therapy


Gene therapy has been studied
for some time

Curing genetic diseases by inserting
the missing gene into a patient's
cells

Usually uses a retrovirus to write the
DNA into your cells
Early experiments seemed
promising but many patients died
in bad reactions to the viral vector

Also some patients contracted
cancer from the gene being inserted
into another gene
Gene Therapy Categories



Currently the only type of gene therapy is
somatic gene therapy

Modifying adult cells in a patient

Most successful in fighting cancer
Potential for germ-line gene therapy

Modifying the genes of gametes or embryos so all
cells will have DNA

Any future children will also have same gene!
We already discussed the potential for
Enhancement gene therapy
Genetic Counseling

Genetic counseling is a
process where a geneticist
will analyze the DNA of
parents and advise them on
the risks for genetic disorders


Accomplished using pedigrees,
DNA sequencing, and medical
history
Genetic counseling is
important for anyone with risk
to their pregnancy
Have a good weekend!