Transcript Genetic Diseases

Genetic Diseases
Syllabus Notes (1-16-08)
• 3.1.1 Chromosomes are made of DNA and proteins.
• 3.1.2 Karyotyping: chromosomes are arranged in
pairs according to their structure.
– Normally, offspring get ½ of their chromosomes in the
egg and ½ in the sperm. Humans get 23 chromosomes
from mom and 23 from dad. Total of 46.
• 3.1.3 Application of karyotyping:
– To check for non-disjunction diseases
• Diseases where the sperm or egg had the wrong number of
chromosomes.
• Common non-disjunction diseases: downs, klinefelters, and
turners syndrome.
Taken from Dwarfism.org:
Note: We are first and foremost human beings, it is
secondary that we are human beings who are of
restricted growth… If people, both average and short
stature, were able to place their humanity before
everything else, the world might be a much better
place. The more we stick labels on each other, the
more we segregate ourselves, and the more we
encourage ignorance and prejudice.
Nondisjunction… when meiosis
goes ‘bad’
Mitosis: cells divide and make copies of
themselves
Meiosis: cells divide and make sperm
and egg… The resulting cells have ½ of
the original genetic material (UNLESS
SOMETHING GOES WRONG!)
Down Syndrome
3 chromosome #21
Characteristics of Down
Syndrome
• 1 in 800 babies are born with Down Syndrome
• Heart defects
• Loss of vision and hearing
• Flattened nose
• Short hands and fingers
• Protruding tongue
• Abnormal head size/shape
Edward’s syndrome
Edward's or trisomy 18:
• structural abnormalities, such as heart defects in
around 40% of babies
• Many babies are stillborn before the end of
pregnancy.
• half of the survivors survive the first month of life
• 10% live to one year of age
Edward’s Syndrome
Trisomy 18
Patau Syndrome (Trisomy 13)
So many organ systems are affected that the mean
survival age is 6 months:
Most often cleft palate, heart defects, nervous
system defects, rocker bottom feet,
and other organ system defects
Klinefelter’s Syndrome (XXY)
Remember: Males = XY
Females = XX
1 in 1000 males have Klinefelter’s Disease.
Most often sterile, breast development in 50% of
cases, some developmental disabilities… Current
practice is to treat the individual as a male, and give
testosterone treatments…
Klinefelter’s Disease
East German swimmers ultimately changed
Olympic law…
…the new law stated that no athlete
may participate as a woman if she
has a Y chromosome.
Turner’s Syndrome (45, X)
“Monosomy”
- short stature
- webbed neck
- lack ovarian development
- underdeveloped breasts
Autosomal
Recessive
Diseases
Tay Sachs
Can’t digest a type of lipid, and this lipid
collects in the brain. Progressively
deteriorates the brain and nervous system
Cystic Fibrosis is not a polyploidy
genetic disease. It is an autosomal
recessive disease.
Cystic Fibrosis:
Too much mucus
and sweat
produced. People
drown in their
own mucus if they
do not have it
vibrated or
pounded out…
eventually affects
the glands of the
pancreas. ½ reach
adulthood.
Mallory Code
Mallory has cystic fibrosis (CF). And diabetes. And serious asthma that
often shortens her breath. The CF also agitates a chronic sinus problem,
giving her blinding headaches. Last summer, she had her ninth sinus
surgery; just before, she played--and won--a major tournament while
wearing a heart monitor. "Wow," Mallory says, shaking her head and
making her blond ponytail bounce. "Guess I'm a pretty big mess."
Cystic fibrosis is an incurable genetic disease affecting approximately
30,000 people in the United States. Three decades ago, average life
expectancy for a child with CF was about 12 years.
Thalassemia
An anemia condition that requires blood
therapy… addition of red blood cells…
Eventually too much iron collects and needs to be
removed, (chelation) Very Very painful…
Chelation Therapy
To help remove excess iron, patients undergo the difficult and painful
infusion of a drug, Desferal. A needle is attached to a small batteryoperated infusion pump and worn under the skin of the stomach or legs
five to seven times a week for up to twelve hours. Desferal binds iron in
a process called "chelation." Chelated iron is later eliminated, reducing
the amount of stored iron.
The Compliance Problem
Compliance with Desferal is vital to the thalassemia patient's long term
survival. However, many patients find the treatment so difficult that they
do not keep up with it or abandon treatment altogether. Lack of
compliance with chelation therapy leads to accelerated health problems
and early death. To combat the compliance problem, researchers are at
work on less stressful new chelators that can improve patient
compliance.
Phenylketonuria Recessive genes
on Number 12
Autosomal
DOMINANT
Diseases
Huntington's Disease
Huntington’s Disease is a
progressive, degenerative
disease that causes certain
nerve cells in your brain to
waste away.
Neurofibromatosis
Cats with a tail, have
mm.
Manx is M_… However, MM
is lethal, and the kittens do
not develop past the umbilical
cord.
Sex-linked Diseases
A ‘bad’ X… only bad if you have
only one X…
Therefore..affects males mostly.
Myotonic muscular dystrophy
Hemophilia:
inability of the blood to clot
Males must inherit the X
chromosome with the genetic
disease from their mother!
(always the case with X-linked recessive diseases)
England’s policy on submitting DNA…
England’s police have unprecedented power to retain
genetic samples from suspects and criminals. The
National DNA Database in England has genetic
profiles of over 3 million citizens.
In a typical month that data base produces hits on 15
murders, 45 sexual offences, and over 2500 car,
theft, and drug crimes.
The average crime clean-up rate increased from 24
to 43 percent.
ETHICS?!
1. The U.S. government should be given the ability
to genetically screen the population.
2. You should NOT have children if you are a
carrier of a genetic disease.
3. Insurance companies should have access to
genetic information.
4. England should be able to take genetic samples
from (innocent) citizens.
Birth defects… genetic?
Environmental?
Sirenomelis
Malformations include a single lower limb, with various degrees of involvement ranging from single to
separate femurs in the same skin shaft, presence of two feet or one foot, to absence of both feet
Hydrocephalus
What numbers do you see?
(People with red/green colorblindness can only see 56 and 25)
Have you seen Little Miss Sunshine?