1. Genetic Disorders & Testing
Warning: sensitive material
Polydactyl- dominant trait

2. review Results of a mutation? 2 types of mutations What is a mutation?
 
What is a mutation?
2 types of mutations
Gene or Chromosomal

3. Review Types of Gene mutations
1. Point mutation: change in one nitrogen base in DNA;
Ex. Substitution
2. Frameshift Mutation
Ex. insertion or deletion of a base
shifts entire sequence for translation

4. review Chromosomal Mutation Change in # or structure of the chromosome
Mitosis & meiosis
usually not passed on because zygote dies
Ex. Deletion
Inversion
Duplication
translocation

5. Nondisjunction occurs when a chromosome pair fails to separate properly during meiosis-can happen to any chromosome pair
2 types:
1. Monosomy: when gamete has one less chromosome than it should
only 45 chromosomes (need 46)
Ex: Turner syndrome- occurs only in females
2. Trisomy: when gamete has one more chromosome than it should
47 chromosomes( need 46)
Ex: Down’s syndrome, extra #21
Don’t forget: you have 23 pairs(46 chromosomes) in each cell in your body

6. GENETIC DISORDERS THESE ARE THE ONES YOU NEED TO KNOW FOR THE TEST!
Autosome- lst 22 pairs of chromosomes
Sex-linked- 23rd pair

7. Autosomal Recessive Disorders
Disorder: Progeria Facts: rapid aging disease, Caused by point mutation Symptoms: thin, bald, old-looking skin Incidence: rare (live to teens or maybe 30’s) Treatments: none

8. Autosomal Recessive Disorders
Disorder: Albinism
Facts: can be caused by a autosomal recessive, autosomal dominant or sex-linked trait; point mutation
Symptoms: absence of pigment in hair, skin, eyes;
defect of melanin production
Photophobic- sunlight painful to eyes
Incidence: common in European descent; less common in African Americans & Asians
Treatments: none

9. Autosomal Recessive Disorders
Disorder: PKU Facts: missing an enzyme that breaks down Phenyalanine (in milk) /it accumulates in the central nervous system Caused by a point mutation Symptoms: can cause mental retardation, abnormal growth patterns Incidence: rare in African Americans & Japanese; more common in Irish Treatments: test newborns- change diet

10. Autosomal Recessive Disorders
Disorder: CF- Cystic Fibrosis
Facts: mucus in lungs & digestive tract is very thick ; caused by point mutation
Symptoms: makes breathing & digestion difficult
Incidence: most common in Caucasians(whites) 1 in white; 1 in 25 carry recessive allele.
Treatments: frequent lungs infections, daily therapy is needed to loosen & remove mucus

11. Autosomal Recessive Disorders
Disorder: Tay-Sachs
Facts: disorder of central nervous system: brain & spinal cord
missing an enzyme which breaks down lipids; accumulates in brain
Symptoms: everything goes in reverse; deteriorates
Incidence: 1 in 27 Jews, Cajuns(Lousiana), & French-Canadians are carriers
Treatments: none; happens within 1st year most children don’t live past 5

12. Autosomal Recessive Disorder/ Codominance
Disorder: Sickle-Cell Anemia Facts: sickle-shaped blood cells block/clot up blood vessels; point mutation Symptoms: pain in joints, anemia, weakness Incidence: 1 in 375 African Americans Treatments: bone marrow transplants, medicines

13. Autosomal Dominant Disorders
Disorder: Huntington’s Disease
Facts: degeneration of nerve cells in the brain because of faulty gene on chromosome # 4(point mutation)
Symptoms: mood swings, depression, memory loss, decline in movements & speech
Death usually occurs years after onset of symptoms. Symptoms begin between ages of
Incidence:Every child of a parent with the disorder has a 50% chance of inheriting Huntington's Disease.
Treatments: none
*Mother murdered/assisted suicide/ her sons in the nursing home here in Ga.

14. Autosomal Dominant Disorders
Disorder: Achondroplasia
Facts: stunted bone growth; type of Dwarfism
Point mutations
Symptoms: Torso is normal but arms and legs are short.
Incidence: 1 out of 25000
Only heterozygotes have this disorder.
Homozygous dominant condition
results in death of the embryo.
Treatments: none

15. Aneuploidy (caused by Nondisjunction)
Disorder: Down’s Syndrome (Trisomy 21) Facts: most common reason for mental retardation; chromosomes failed to separate Symptoms: mental retardation, slanted eyes Incidence: 1 in 900; most cases not inherited Treatments: none

16. Aneuploidy (caused by Nondisjunction/ Trisomy)
Disorder: Klinefelter Syndrome Facts: XXY - Trisomy- chromosomes failed to separate Symptoms: male, taller than average, longer limbs, sterile, may have some mental retardation Incidence: Treatments: none

17. Aneuploidy (caused byNondisjunction/ Monosomy)
Disorder: Turner’s Syndrome Facts: female, only 1 X b/c of Nondisjunction Symptoms: sterile, lack of sexual development(no ovaries), short stature Incidence: Treatments: none

18. Chromosomal mutation Disorders
Disorder: Cri Du Chat Syndrome Facts: missing piece of chromosome # 5 (deletion) Symptoms: mental retardation, high-pitched cry that sounds like a cat. Incidence: avg. 1 in 40, 000 Treatments: none

19. Sex-linked Disorders. write Xm Xm , XmY
Sex-linked Disorders *write Xm Xm , XmY *most disorders are x-linked, recessive
Disorder: Muscular Dystrophy (MD) (duchenne’s only) Facts: recessive, x-linked; many types of MD Symptoms: muscle loss & weakness Incidence: mainly in males; all ethnic groups have an equal chance of MD Treatments: physical therapy , braces, wheelchair

20. Sex-linked Disorders
Disorder: Hemophilia Facts: recessive, x-linked; blood does not have clotting factors Symptoms: bleed excessively or to death Incidence: mainly in males ; Royal Family Treatments: inject themselves with purified clotting factors to prevent or stop bleeding

21. Sex-linked Disorders Disorder: Color-blindness
Facts: recessive, x-linked disorder; Cones in eyes(color receptors) are absent or lack of pigment
Symptoms: cannot tell difference between certain colors
Incidence: mainly in males- passed from mother;
red-green color blindness most common
Seeing only black/white is rare
Treatments: none

22. 1. Karyotyping: pictures of chromosomes are matched up according to size
4 Methods of detection

23. methods of detection cont
2. Ultrasound: sound waves/ image. Used to detect abnormalities of limbs, organs, etc.
3. Amniocentesis: fluid surrounding the fetus is drawn out by needle, fetal cells collected/ grown Chromosomes karyotyped

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