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Think It Through
A Hereditary Disease
Linda is a sophomore in high school. She has
already lived longer than is common for a person in
her condition. She has cystic fibrosis. Her parents
don’t have the disease; neither does her brother or
sister. However, the disease is hereditary.
Linda appears healthy to those who meet her,
but she doesn’t have much longer to live. Every
day she undergoes therapy to thin the mucous that
affects her breathing and digestion.
Her family members help her with the daily
treatments. They have grown very close to one
another, realizing that Linda’s life will be short. They
have also tried to help her live a normal life. She
does very well in school. Her grades are high and
she has won honors for her achievements.
The stress constantly affects her family.
Frequent visits to the hospital strain the family
finances. The daily therapy routines take enormous
time and energy. Family members also feel the
emotional strain of not knowing just how long Linda
will live.
Questions to Guide Your
Thinking
1. Who in Linda’s family are carriers of cystic
fibrosis? Using “D” for a dominant healthy gene
and “d” for a gene for cystic fibrosis, identify a
gene-type for both her mother and her father.
2. What are the chances that each child in this
family would have cystic fibrosis? What are
the chances that Linda’s brother, Dan, and her
sister, Tricia, are carriers of cystic fibrosis? (Use
a Punnett square to diagram the answer.)
3. Why might Linda’s siblings seek genetic
counseling before getting married and starting
their own families? What information should the
counselor be able to provide? How could this
information affect a marriage?
4. Linda’s family environment has been affected
by her disease. How has her family responded
to stimulate Linda’s growth and development?
Because of Linda’s disease, in what areas might
the growth of other family members be slowed?
In what areas might their personal growth be
enhanced?