Methods of Detection & Genetic Disorders

1. Methods of Detection & Genetic Disorders

2. Methods of detectioni. Ultrasound: sound waves are used to generate an image of the unborn child. Used to detect abnormalities of limbs, organs, etc.

3. ii. Amniocentesis: fluid surrounding the fetus is drawn out by a needle, fetal cells are collected & grown in a lab, chromosomes are then karyotyped.

4. iii. Chorion villi sampling: a sample of the chorion(membrane surrounding the fetus) is taken, chemical tests and karyotyping is performed.

5. iv. Karyotyping: pictures of the chromosomes are matched up according to size in matching pairs a. fetal cells are obtained by amniocentesis or chorionic villi sampling b. fetal cells are grown in a lab, a photograph of the chromosomes is made c. the chromosome pictures are cut out and arranged in matching pairs

7. These are pictures of human karyotypes Left-female Right-male Notice the difference in the last pair of chromosomes-these are the sex chromosomes, in females they will be the same size, males will be different

8. This is a karyotype of a child with downs syndrome, notice the extra 21st chromosome, there should be 2 at each number(2 x 23 pairs=46)

9. B. Genetic disorders 1. Cystic fibrosis(CF) a. recessive trait found mostly in white Americans b. mucus in lungs & digestive tract is very thick c. makes breathing & digestion difficult d. frequent lungs infections, daily therapy is needed to loosen & remove mucus

10. 2. Sickle-Cell Anemia a. recessive trait found mostly in black Americans & people from Sudan b. red blood cells are shaped like half moons instead of round c. red blood cells can clot together, don’t carry as much oxygen d. can lead to loss of sensation in limbs, loss of appendages e. no cure, can only treat symptoms

11. 3. Tay-Sachs Disorder: a. recessive trait found mostly in Jewish communities b. disorder of central nervous system: brain & spinal cord c. missing an enzyme which breaks down a certain lipid. d. since it does not break down, the lipid accumulates in the cells of the brain

12. E. results in blindness, loss of movement, deafness, mental deterioration f. no treatment or prevention, death usually occurs before the age of 5

13. 4. (PKU) a. recessive disorder b. missing an enzyme that breaks down a certain amino acid c. because this is not broken down, it accumulates in the central nervous system d. amino acid is found in milk & infant formula, so test is performed a few days after birth e. can cause mental retardation, abnormal growth patterns

14. 5. Sex-Chromosome Disorders: a. XO: Turner Syndrome: females, no ovaries, do not develop secondary sexual characteristics She is missing an X chromosome, so that’s why you see masculine traits

15. b. XXY: Klinefelter Syndrome: male, taller than average, longer limbs, sterile, may have some mental retardation

16. C. XYY(Jacobs syndrome): male, fertile, taller than average, produces extra testosterone

17. D. XXX: female, fertile, produces extra estrogen