Download mutation lesson - Maria Nedwidek

NEDWIDEK, MARIA
1
THE MUTATION CONCEPT: taking the bad with the good.
Teacher copy
Dr. Nedwidek Oct‘13 (GR)
Aim: What are the profits and perils of mutation?
Pre-assessment (night before, in notebook): read Kraus pp 391, 392-399. Identify the basis
for heterozygote advantage. State three possible effects of mutation on human survival and
give an example of each in nature. Define mechanism. Bring your responses with you to
class for discussion. I’ll also return your index cards eliciting the basis for genetic disease.
We start with Discussion of MUTATION EFFECT (allow 10 minutes): First, we consider
the significance of mutations regarding human survival based on your lesson preparation
detailed above.
Look at this before class if you have time. Here is a 1-minute video to explain the
mechanism of one genetic disease we will discuss in class (text of audio below):
http://www.dnai.org/lesson/go/17604/14098
DNAi Location: Genome>Tour>genome spots>Sickle cell>About sickle cell: “Sickle cell
anemia is a genetic disease that affects hemoglobin, the oxygen transport molecule in the
blood. The disease gets its name from to the shape of the red blood cells under certain
conditions. Some red blood cells become sickle-shaped and these elongated cells get stuck
in small blood vessels so that parts of the body don't get the oxygen they need. Sickle cell
anemia is caused by a single code letter change in the DNA. This in turn alters one of the
amino acids in the hemoglobin protein. Valine sits in the position where glutamic acid
should be. The valine makes the hemoglobin molecules stick together, forming long fibers
that distort the shape of the red blood cells, and this brings on an attack.”
PHYSICIANS-IN-TRAINING ACTIVITY (allow <5 mins to diagnose; >10 mins to share):
Today, you, THE FUTURE DOCTORS OF AMERICA will use notes sent and distributed to
you as well as an advanced graduate-level clinical genetics text (Thompson and Thompson
Genetics in Medicine) to diagnose, state inheritance for, and initiate treatment for 8
patients afflicted with 8 different genetic diseases. You will then convene with your
attending physician, Dr. Nedwidek, for “grand rounds” to exchange ideas about your
diagnoses and treatment options. Each group will be given a patient history. From this,
part of your group will choose from the list of diseases that, according to your resources,
fits the profile. You will use the text and the bulletin board to briefly articulate one
standard treatment for the disease you diagnose. Only one disease on your list (PKU) is
extremely easy to diagnose and treat. Within the remaining 7 diseases, the standard of care
for Hemophilia, which is also easy to diagnose, is also relatively simple. We will talk about
why this is the case at the end of “grand rounds”. Your groupings were assigned
Wednesday, so you are ready to help your patients!
2
NEDWIDEK, MARIA
Teacher copy
GROUP # ______; NAMES:___________________________________________________________________________
AR=autosomal recessive;
XR=X-linked recessive;
GROUP:
_________
_________
_________
_________
_________
_________
_________
_________
AD=autosomal dominant; M.D.=muscular dystrophy, below
XD=X-linked dominant;
Thompson’s purple pages are alphabetical by disease
Disease
Huntington
Holoprosencephaly
Cystic Fibrosis
Phenylketonuria
Tay Sachs
Fragile X
Hemophilia
Duchenne M.D.
Inheritance
_____________
_____________
_____________
_____________
_____________
_____________
_____________
_____________
Thompson page ref
240-242 & purple
338,339 & purple
222-225 & purple
207-208; Kraus 391
210-212 & purple
242-243 & purple
269, 274 & purple
225-229 & purple
Group 1: Ashkenazi Jewish couple brings their six-month old daughter to the doctor with a
progressive loss of motor skills and lethargy. Low visual acuity is noted.
Group 2: 2-year old Caucasian girl has poor growth, coughing, and frequent, chronic upper
respiratory infections. Tests reveal high sweat chloride levels.
Group 3: 6-year old boy presents with extreme cognitive delay and hyperactivity; learning
disabilities and a range of cognitive delay run in the family.
Group 4: 37-year old man had a child die at birth and presents with facial deformity, mild
cleft lip, and mild hypotelorism (eyes close together).
Group 5: Three days after birth, blood test on a 3-day-old infant reveals high blood levels
of phenylalanine.
Group 6: 30-year old male with slow clot time and high propensity to bruise reveals low
levels of clotting factor 9.
Group 7: 6-year-old boy presents with muscle weakness, a Gower’s sign, and
developmental delay. His high creatine kinase levels suggest myopathy (muscle disease).
Group 8: 45-year-old man with declining memory and loss of motor control has a family
history of similar late onset symptoms.
When I call time, you will read your diagnosis (the name of the disease) and
inheritance pattern plus you will read the treatment you suggest. Remember, we must
consider why PKU and Hemophilia are so easy to treat at this time in history.
Suggested treatment: