Download “Lorenzo`s Oil” Film Assessment – “Tracing a Genetic Disorder in a

“Lorenzo’s Oil” Film Assessment – “Tracing a Genetic Disorder in a
Family”
Genetic diseases are inherited from parents to offspring. In some cases, parents have children who have a
genetic disease even though the parents themselves do not show the trait or disease. A person who does not
have disease (or show the trait), but who is capable of passing the trait to their offspring is called a carrier.
Sex-linked traits are those that are passed on from parents to offspring via the sex chromosomes (X or Y).
ALD (adrenoleukodystrophy) is a sex-linked genetic disorder located on the X chromosome, and is a
recessive disorder.
Mr. And Mrs. Odone have a son, Lorenzo, who has Adrenoleukodystrophy (ALD). ALD is a genetic disease
that causes large amounts of long chain fats to build-up and destroy the myelin sheath around nerve cells.
ALD symptoms include dementia, deafness, aphasia, and eventually death. The Odones told a genetic
counselor that no one in their family was afflicted with ALD. The genetic counselor suggested that Mrs.
Odone’s sisters and their children be tested due to the fact ALD is passed from mother to son and therefore
they may be carriers of the disorder.
Even though carriers do not express the disorder, they can pass it on their sons. Females have 2X
chromosomes, and if they have one with the ALB gene the other X chromosome with a “normal” gene will
be expressed. If, however, they were to pass the chromosome with ALD on to their son, the son would have
no other X chromosome, since males have one X from the mother and on Y from the father, to “counteract”
the effects of ALD.
Set up a Punnett square to show the gene types for each of Lorenzo’s parents and for Lorenzo. Use “A” for
the dominant gene and “a” for the recessive gene.
MOTHER
X
X
Y
1. What is the gene type for Mr. Odone? ______________
For Mrs. Odone?__________ What is Lorenzo’s gene
type?___________Explain your results:
Y
2. The Odone’s Genetic Counselor (physician) told them that they have a chance of having another child
with ALD. Is this true? Explain.
3. With the new treatments, males with ALD are able to survive to reproductive age. Suppose a father who
has ALD married a woman who was a carrier. Make a Punnett square to demonstrate whether the would
have children with ALD or children who would be carriers of the disease.
MOTHER
X
Y
X
Y
Explain the results:
Lorenzo’s Oil Punnett Square Activity Page
1.What are the chances of Augusto and Michaela Odone having another boy with ALD? Provide a Punnett
square as evidence.
Genotypes:
Michaela:
Augusto:
Lorenzo:
2. Michaela and all of her sisters have red hair. Their mother has brown hair. What possible colors does their
father have? Show the possible Punnett squares. Brown hair is dominant.
3. Show the genotype (sex chromosomes) of Michaela’s sisters. Dedra- carrier, no kids; Mariah- not a
carrier, one boy; Caneese- carrier, two girls.
4. Why would knowing if they were carriers be helpful? What are the chances of the daughters of Caneese
being carriers? Demonstrate with a Punnett square.
5. As a Genetic Counselor, what additional information would you give Caneese and her husband?
6. Wendy Gimbell has 2 boys. One recently died from ALD. Draw a Punnett square to represent this family.
What are Jake’s chances of having ALD? As a Genetic Counselor, how would you tell this family and child
that they have inherited ALD?
7. If you were to investigate Michaela’s family history, what do you think you would observe?
8. Why do you think Eller and Loretta (directors of the ALD Foundation) are so against disseminating the
information about the results of the Odone’s “experiment” with the oil dropping Lorenzo’s fat blood levels
50%?
9. What is going to happen now that Lorenzo’s Oil is helping boys with ALD live/ survive?
10. If boys with ALD survive to reproduce, they may pass on the ALD gene to their offspring. Diagram a
Punnett square of the possible outcomes of an ALD male and his spouse.