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.

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.

Taken from Dwarfism.org:

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 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

Edward’s SyndromeTrisomy 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 RecessiveDiseases

Tay SachsCan’t digest a type of lipid, and this lipid

collects in the brain. Progressively deteriorates the brain and nervous system

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.

Cystic Fibrosis is not a polyploidy genetic disease. It is an autosomal recessive disease.

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.

ThalassemiaAn 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 battery-operated 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

AutosomalDOMINANT

Diseases

Huntington's Disease

Huntington’s Disease is a progressive, degenerative disease that causes certain nerve cells in your brain to waste away.

Neurofibromatosis

Manx is M_… However, MM is lethal, and the kittens do not develop past the umbilical cord.

Cats with a tail, have mm.

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?