Transcript Cross-dressing or Crossing-over: Sex Testing of Women Athletes

Sex Testing of Women Athletes
The Story of Olympic Silver Medalist Santhi Soundarajan
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Santhi’s Story
http://www.ibnlive.com/videos/28851/how-are-athletes-gender-tested.html
Santhi Soundararajan won the silver
medal in the 800-meter race at the
2006 Asian Games in Doha, Qatar.
Following her silver medal
performance, her sex was officially
questioned.
On December 18, 2006 Santhi was
stripped of her medal based on the
results of gender determination
testing
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How is sex determined in humans?
• Anatomy: Primary and secondary sexual
characteristics - genitalia, body hair, pelvis, etc.
• Physiology: Function and interaction of the sex
organs including concentrations of sex
hormones such as estrogen, progesterone, and
testosterone.
• Genetics: Type and number of sex
chromosomes (e.g. X or Y) and/or genes (e.g.
SRY)
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Question: Could Santhi
have an XY karyotype and
be female?
A: No, an XY individual is always male.
B: Yes, this is common.
C: Yes, if a male-determining control gene is
missing on her Y chromosome.
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Transition Slide
• Read the “History of Gender Testing for
Olympic Athletes” in your lab packet
• The Case
– You are part of a team of doctors which
includes a gynecologist, endocrinologist and
psychologist charged with examining Santhi.
Your team is responsible conducting both
physical and biotechnological examinations of
Santhi in order to correctly identify her
gender.
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The Tests
Your team will run four tests:
•Physical exam – analyze the results of physical /
anatomical tests
•Abbott Testosterone ELISA – Enzyme Linked
ImmunoSorbant Assay that measures the amount of
testosterone hormone in a sample and works by using an
antigen-antibody immune reaction
•Karyotype – identifies the gender of an individual based
on chromosome set
•Gel Electrophoresis – analyzes a sample for the
presence of the SRY (male determining gene) located on
the Y chromosome
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Santhi’s Karyotype
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Santhi’s DNA Gel
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Sources of Genetic Variability in Meiosis
Independent Assortment
•
Each pair of homologous
chromosomes lines up at
Metaphase I plate.
•
There is a 50:50 chance
that a daughter cell will
get one or the other copy
of the chromosome.
Animation:
http://wps.prenhall.com/wps/media/objects/487/498795/CDA10_2/CDA10_2b/CDA10_2b.htm
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Crossing Over
• Crossing over can occur anywhere along
the autosomes.
• In males, the sex chromosomes (X and Y
chromosomes) normally cross over only at
their tips.
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How is Sex Characterized in
Humans?
In addition to anatomy, physiology, and
chromosomes, there is a 4th answer:
Genes: Specific genes determine
whether an embryo will develop as a
male or female.
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SRY (Sex- Determining Region of the
Y chromosome) Gene
• Early in development, the
immature gonads of males and
females are indistinguishable.
SRY
gene
• Males: In the 7th week of
development, the SRY gene on
the Y chromosome activates a
number of genes, and the
gonads develop as testes.
• Females: With no SRY gene,
gonads develop as ovaries by
default.
Y
X
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Can you have an XX male or XY
female?
• Watch this video:
http://www.hhmi.org/biointeractive/media/meiosis-lg.mov
• What sex is XX (SRY+)?
• What sex is XY (SRY-)?
Sex reversal occurs in 1 in 20,000 births!
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If you were a member of the Asian
Games medal committee and
Santhi’s karyotype revealed that
she is XY and SRY-, what would
you do?
A: She has female genitalia, allow her to
keep her medal.
B: She is genetically male, take her medal
away.
C: Perform additional tests.
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What do you think about
requiring gender testing for
female athletes in international
competition?
A: It should be banned because gender
determination is so complex.
B: It is necessary to ensure an even playing field.
C: It is necessary, but needs to include a large
number of genetic tests to ensure fairness.
D: It should be required for all athletes, both male
and female.
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What about Santhi
Soundararajan?
Santhi was stripped of her silver medal.
An anonymous official in the know has
reported that Ms. Soundarajan's tests
revealed more Y chromosomes than are
usually present in the genetic make-up of a
female. No official statement has been made.
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