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1. Copyright © 2021 by Jones & Bartlett Learning, LLC an Ascend Learning Company. www.jblearning.com.
CHAPTER 12
Genetic
Diseases and
Other Inborn
Errors

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©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Environmental Teratogens
 Infectious pathogens
– Syphilis, rubella, toxoplasmosis
 Environmental chemicals
– Mercury
 Drugs
– Accutane, thalidomide, hormones
 Alcohol
 Cocaine and heroin

3. Copyright
©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Genetic Diseases
 Chromosomal abnormalities
– Down syndrome
 Mendelian genetics
– Autosomal dominant
– Autosomal recessive
– X-linked

4. Copyright
©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Genetic Diseases
 New mutations may cause genetic diseases.
 Severity of some genetic conditions may be affected by environment.
– Anencephaly and spina bifida are examples.
– Folic acid supplements can reduce risk.
 Genes influence susceptibility to adulthood diseases.
 Mental disorders are believed to be genetic.

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©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Newborn Screening
 There is a public health mandate of preventing death and disability from many
genetic diseases.
 We can test drops of blood from newborns for metabolic abnormalities.
 All newborns in the U.S. are screened for at least two conditions, PKU and
hypothyroidism.
 States vary in conditions screened for.
 Most conditions are autosomal recessive.
 Early diagnosis can prevent or reduce permanent damage.
 Some conditions are complicated to test for:
– E.g., cystic fibrosis.
 CDC recommends screening for profound hearing loss.

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©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Carrier Screening
 Screen for recessive genes in high-risk populations:
– Prenatal screening for HIV
– Tay-Sachs disease in Jews
• Screening is encouraged by Jewish leaders.
– Sickle-cell disease in African Americans
• Screening program in the 1970s was misunderstood and poorly conducted.

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©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Prenatal Diagnosis
 Down syndrome
 Anencephaly and spina bifida
 Only treatment may be abortion.

8. Copyright
©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Genomic Medicine
 Human Genome Project
 Many potential benefits
 Many ethical dilemmas
 Cancer genes
– BRCA1 and BRCA2
 Targeted therapies
 Single-nucleotide polymorphisms
– HapMap

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©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Guidelines for Genetic Screening
 Screen newborns only when it clearly benefits the newborn, diagnosis can be
confirmed, and when treatment and follow-up are available.
 Carrier identification should be voluntary and confidential, and it should include
counseling.
 Include education and counseling with prenatal diagnosis.
 Tests should be high quality and FDA evaluated.
– More government oversight of laboratory proficiency is needed.
 Provide more genetics education to the public.

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©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Discussion Question 1
 What are the ethical issues involved with prenatal diagnosis of each of the
following genetic diseases: Down syndrome, anencephaly, and Huntington’s
disease?

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©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Discussion Question 2
 From an ethical perspective, how is newborn screening different from screening
people in certain racial or ethnic groups for recessive genes?

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©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Discussion Question 3
 What would be the benefits and drawbacks of including tests for BRCA1 and
BRCA2 in newborn screening programs?

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©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Discussion Question 4
 Visit the website of the CDC Office of Public Health Genomics,
www.cdc.gov/genomics.
 Review the most recent Weekly Updates.
 What issues are hot in the area of genetics and disease?

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©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Discussion Question 5
 Because genes affect people’s risk for many diseases, the Surgeon General is
encouraging Americans to learn about their family’s health history.
 Visit the Family History Initiative website, www.hhs.gov/familyhistory. You can
download a form for recording your family’s health history.
 Do you think this information will be helpful to you in understanding your health
risks?
 Can you think of any drawbacks to trying to collect the information?

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©
2021
by
Jones
&
Bartlett
Learning,
LLC
an
Ascend
Learning
Company.
www.jblearning.com
Discussion Question 6
 Visit the website of the National Human Genome Research Institute,
www.genome.gov.
 What is the ELSI program?
 What are some of the ethical, legal, and social issues the program is studying?