Chapter 15 Flashcards
copy-number variants (CNVs;
-usually either deletions or duplications of stretches of DNA)
-Copy number variants (CNVs) are a group of short or long repeats of one or many base pairs within a chromosomal region. These may be inherited or new (de novo)
-CNVs that occur during human repro- duction a.nd can be associated with an increased risk for a range of psychiatric illnesses, intellectual disability, autism spectrum disorders, and epilepsy, and they can even occur in seemingly healthy indi- viduals.
-More research needs to be done to establish the lifetime risk for persons who carry these CNVs
behavioral genetics.
field that focuses on the way gene variants affect how people act
Autism
Three groups of symptoms that include:
-difficulty with social interactions, -communication problems,
-and a narrow range of repetitive behaviors and interests
autism spectrum disorders (ASDs)
describes collections of symptoms that are like autism but do not quite meet the definition of PDD.
Table 15-1
Examples of Known Genetic Causes of Autism Spectrum Disorders
biologically plausible.
This means that a given gene is likely involved based on knowledge of the protein it encodes. (These are also known as candidate genes.) Some genes that have been associated with ADHD are involved in the development of neurons and transmission across the synapse.
externalizing psychopathology
-includes problems such as alcohol and other drug dependence. It also includes conduct disorders and antisocial personality disorder.
-Experts propose that a group of gene variants can increase susceptibility to all of these categories; however, other gene variants exist that are specific for alcohol and other drug dependence.
Summary
The genetics of psychiatric illness and behavioral disorders continues to evade definitive answers despite increased research aimed at better understanding the causes and interrelationships.
-Pharmacogenomics is identifying which medication is correct for the right patient. The use of genetic technologies is beginning to assist in the identification of causes of associations. although many barriers remain. This specialty holds exciting opportunities for persons interested in unmasking answers about mental illnesses and disorders.
• In the future, pharmacogenetics may help clinicians find a safe and effective psychotropic drug with minimal side effects to better treat patients.
• Complex biological pathways and the contributions of environmental factors make predicting responses to psychotropic drugs difficult.
• A few neuropsychiatric disorders, such as Huntington disease and fragile X, are caused by problems with single genes.
• Most psychiatric problems are complex (multifactorial), combining the effects of several genes working together with the environment.
• Genome-wide association studies (GWASs) can be helpful in identifying genes with variations that increase susceptibility to psychiatric disorders.
• Direct-to-consumer genetic tests exist; however, as with genetic testing to diagnose mental illness in general, their clinical usefulness is questionable.
• Behavioral genetics is the field that focuses on the ways in which gene variants affect how people act.
• Autism is a disorder of social interaction and language use that is often viewed as a pervasive develop- mental disorder called autism spectrum disorder.These disorders may have some genetic risk factors in
common.
• Monozygotic twin concordance for autism is between 70% and 80%, meaning that the genetic con-
tribution is very high.
• Symptoms of regressive-onset autism begin between 18 and 24 months of age, which is the age when many children receive childhood immunizations; however, evidence does not exist that links immuni-
zations and autism.
• Genes coding for proteins important in the generation and transmission of neural impulses have been
associated with susceptibility to autism.
• Attention-deficit hyperactivity disorder (ADHD) seems to run in families; however, it does not follow
an obvious pattern of transmission.
• When phenotypes vary (e.g., schizophrenia), genetic studies are more difficult.
• Epigenetic factors may be important in psychiatric disorders such as schizophrenia.
• Both genetics and environment are important in determining susceptibility to schizophrenia.
• The heritability of major depression and bipolar disorder is very high, and both can be found in the same family.
• Addictive disorders are closely linked to other psychiatric problems, and they have both genetic and
environmental contributions to susceptibility.
• Variations in genes that encode neurotransmitters such as y-aminobutyric acid (GABA) have been
associated with alcohol dependence.
• The difficulty in placing personaliry disorders in discrete categories makes genetic studies more difficult.
• Personality disorders are highly heritable, much like normal personality traits.
The risk of schizophrenia is reported to be highest under which of the following conditions?
a. Advanced paternal age
b. Birth during a famine
c. Epigenerics
d. Twinning
B
Which statement best describes why it is difficult to predict responses to psychotropic drugs?
a. Most psychiatric problems have so many symptoms that drug responses are not easy to assess.
b. Many patients are not compliant with their medication regimens due to the side effects.
c. Complex biological pathways make drug targeting difficult.
d. Most of these diseases are primarily due to environmental facrors, so targeting genes will have
minimal effect.
C
Biological factors that have a known association with bipolar disorders include which of the following?
a . Acerylaldehyde
b. Calcium channels
c. GABA
d. Major histocompatibility complex
B
An epidemiological study reveals that the overall heritability in a population with an identified personality disorder is 50%. Which of the following is incorrect?
a. Half of the risk is genetic, and the other half is environmental.
b. The heritability is 0% environmental and 100% genetic.
c. There is a 50% chance that the risk is genetic.
d. The heritability is 100% environmental and 0% genetic.
D
How is the concept of “externalizing psychopathology” useful in explaining the genetics of psychiatric and addictive disorders?
a. Conduct disorders include addictive behaviors.
b. Antisocial personality disorder is highly heritable.
c. All genes for these disorders are shared; environment determines which disorder will occur.
d. Some gene variants increase susceptibility to all of these disorders, and others are specific co each
individual disorder.
D
CASE STUDY
Sally has alcoholism and has suffered from bipolar disorder on and off throughout her life. Her father drank heavily and was verbally abusive during her childhood. Sally had done well until the birth of her daughter 15 years ago when she started drinking heavily every night after dinner. She is happily married to a very understanding man. Sally has two brothers and two sisters who also have alcoholism. The sisters have had problems with recurring major depression but have been treated succ essfully with antidepressants. They go oft the medication when they feel better. Sally is most concerned about her daughter. who shows signs of cycling between being abnormally lively and spending irresponsibly and seeming down and not communicating with friends or family for weeks at a time. Sally found a couple of empty beer cans in her room last week. The daughter is not interested in seeing a therapist and does not acknowledge that anything might be wrong. Sally is afraid that her daughter has bipolar disorder and feels guilty about “causing” her older daughter’s problem.
1. Do you think a genetic link could exist for the problems of Sally’s dad, Sally and her siblings, and Sally’s daughter?
2. Would referral for genetic counseling benefit this family? Why or why not?
3. Do you think that a medication that is successful in treating Sally’s bipolar disorder might be useful
for her daughter? Why or why not?
4. Should Sally be concerned about the possibility that her daughter is drinking alcohol?
5. How might genetic information help Sally’s daughter agree to seek diagnosis and treatment for her problems?
