Pedigree Analysis Key - Iowa State University

Supplemental Instruction
Iowa State University
Lilli Howard
Dr. Vollbrecht
1. What three factors complicate the task of studying the inheritance of human
 Long generation time
 Small family size
 Controlled mating is not possible
2. Draw symbols for:
a. Unaffected male
b. Affected female
c. Obligate Carrier w/ unknown sex
d. Asymptomatic carrier w/ unknown sex
e. Deceased male
f. Identical female twins
3. How does the pedigree of an autosomal recessive trait differ from the pedigree of an Xlinked recessive trait?
-X linked is passed from mother to ½ of her children or from father to all of his
daughters. It always shows in men.
-Autosomal recessive is passed from mother or father to ½ of their offspring and only
shows up when homozygous
4. What is genetic counseling?
Genetic counseling provides information and support to people who have, or may be at risk
for, genetic disorders. A genetic counselor meets with you to discuss genetic risks. The counseling may be for yourself or a family member. Or you may get it when you are planning or expecting a baby. You may follow up with genetic testing.
There are many reasons to seek genetic counseling. You may consider it if you
Have a personal or family history of a genetic condition or birth defect
Are pregnant or planning to be pregnant after age 35
Already have a child with a genetic disorder or birth defect
Have had two or more pregnancy losses or a baby who died
Have had ultrasound or screening tests that suggest a possible problem
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