This document discusses genetic mutations and disorders. It defines different types of mutations including point mutations, chromosomal mutations like inversions, translocations, deletions and duplications. It explains conditions that can result from nondisjunction including monosomy, trisomy, Down syndrome, Patau's syndrome and Edward's syndrome. Methods for detecting genetic disorders like ultrasound, amniocentesis and chorionic villus sampling are outlined. Several single gene and chromosomal disorders are described in detail such as cystic fibrosis, hemophilia, sickle cell anemia, Angelman syndrome, Prader-Willi syndrome, Klinefelter's syndrome and Turner's syndrome.
3. Changes in
chromosome
structure
1) INVERSION:
the order of genes on
a chromosome is
inverted
Chromosomal Mutation:
2) TRANSLOCATION:
•the movement of a
chromosome fragment to
a nonhomologus
chromosome
4. 3. DELETION
Loss of a few bases
Loss of large regions
of a chromosome
4. DUPLICATION
Duplication of a few
bases
Duplication of large
regions of a
chromosome
6. NONDISJUNCTION
Nondisjunction:
chromosome pair fails
to separate properly
during meiosis
Monosomy:
gamete has 1 less
chromosome than it
should
45 chromosomes
is the result
Ex: Turner syndrome
Missing a sex
chromosome
7. Trisomy:
Gamete has 1
more chromosome
than it should
Result is 47
chromosomes
Ex: Down’s
Syndrome
Extra #21
chromosome
8. Methods of Detection
Ultrasound:
Sound waves are used to
generate an image of the
unborn child.
Used to detect abnormalities of
limbs, organs, etc.
Chorion villi sampling:
•Take sample of the chorion
–(membrane surrounding
fetus)
•Chemical tests and Karyotyping performed
9. Amniocentesis:
• Fluid surrounding the fetus is drawn out by
needle
• Fetal cells are collected and grown in a lab.
• Chromosomes can be then Karyotyped
11. Down’s Syndrome (DS)
Excess # 21 chromosome
Prenatal testing can be done
Result of chromosomal mutation
1 in 900 people born with this
Likelihood of having a child with DS
increases with advancing maternal age
Symptoms: mental retardation, upward
slant to eyes, small mouth, abnormal ear
shape, decreased muscle tone
No cure
12. Patau’s Syndrome &
Edward’s Syndrome
Cardiac abnormalities
Very severe conditions
Most affected infants
die during first few
weeks of life
17. Klinefelter’s Syndrome
47, XXY
1 in 1000 male live births
Mild learning difficulties
Taller than average with
long lower limbs
Show mild enlargement of
breasts
Infertile (absence of
sperm)
Treat with testosterone
18. Turner’s Syndrome
45, X
Low incidence
Look normal
Ovarian failure
Normal intelligence
Short stature
Estrogen therapy
19. Fragile X Syndrome
Most common inherited
cause of mental
retardation
1 in 2000 males
High forehead,
prominent jaw, autism
Gap in X chromosome
21. Cystic Fibrosis (CF)
Recessive disorder
Mutation stops production of
protein in lung cells,
pancreas
Thick mucus, bacterial
infections in lung
“sweat test”
Most common in
Caucasians (1 in 3300)
Chest percussions, diet
supplements
Shortened life expectancy
22. Hemophilia
Sex-linked
Failure of blood to clot
Rare in females
Injections with clotting factors to stop
bleeding episodes
$350,000 a year in treatment
23. Sickle Cell Anemia
Mutation in blood protein
“sickle” shape to RBC
Screening tests
Most common in African-Americans
(1 in 375)
Pain associated with blocked vessels, causes
anemia (fatigue)
Common where
mosquito-borne
malaria is present
24. PKU
Mutation disrupts function of enzyme
Leads to high phenylalanine levels in brain
(poisons)
Mental retardation, epilepsy
Screening newborns (heel prick)
1 in 10,000 Caucasian births
Extremely rare in African-Americans
Look normal
Need low-protein diet,
smelly formulas
25. Self Quiz:
Quick Check for Understanding
1. Which of the following is an X-linked
disorder?
A. Angelman B. hemophilia c. Down syndrome
2. How is PKU tested for?
A. amniocentesis b. heel prick c. X-ray
3. How are CF patients treated?
A. testosterone injections b. chest percussions
4. Turner’s Syndrome is
A. 45, X b. 46, XX c. 47, XXY
5. Patients with Klinefelter’s Syndrome are
A. all male b. all female c. male or female