Question 1

Why are complex or multifactorial disorders more commonly expressed among adults than among children?&#10;A)As adults age, there is more time for environmental factors to influence the expression of a genetic disorder.&#10;B)Gene expression in adults is greater than in childhood as a result of age-related amplification of gene copy numbers.&#10;C)Children have better DNA repair mechanisms than adults and are more likely to correct a predisposition for a complex disorder.&#10;D)In order for a complex or multifactorial disorder to be expressed in childhood, the child must be homozygous for the genetic mutation.

Accepted Answer

Complex or multifactorial disorders are not single-gene conditions. They are the result of polygenic input and environmental interactions. Thus, the longer a person has been exposed to the environment, the more input the environment has on the expression of a polygenic problem. DNA repair efficiency has no relationship to age; it is related to the quality of the repair mechanisms a person inherits. Although gene amplification can occur, it is neither an age-related phenomenon nor a cause of adult-onset complex disorders.

Question 2

Which condition or factor most strongly supports a genetic basis for the development of type 2 diabetes mellitus?&#10;A)Type 2 diabetes occurring in two cousins before age 30 years&#10;B)The disease developing in a person whose parents also have type 2 diabetes&#10;C)The fact that the incidence of disease concordance is higher in dizygotic twins than in monozygotic twins&#10;D)The fact that type 2 diabetes is more prevalent in one city than it is in another city of similar size

Accepted Answer

Although type 2 diabetes mellitus (T2DM) does not strictly follow Mendelian patterns of inheritance, the evidence for genetic input is strong. About 7% of people in the general population will get T2DM at some point in their lives, but 30% to 40% of people who have one affected parent will become affected. The risk is 70% for people who have two affected parents. Higher concordance among dizygotic twins than among monozygotic twins supports more environmental input than genetic input. Incidence between two cities is not related to genetic influences. Cousins are not first-degree relatives. The presence of the same relatively common disorder only in two cousins within a kindred does not provide strong support for a genetic influence.

Question 3

Which factor is consistent with multifactorial (complex) genetic disease?&#10;A)Expression of the trait often involves mutations in several genes.&#10;B)Monozygotic (identical) twin concordance is 100%.&#10;C)Genotype consistently predicts phenotype.&#10;D)It tends to be autosomal dominant.

Accepted Answer

Multifactorial (complex) genetic disease involves the actions of several gene variants contributing a small amount of risk and/or the combination of genetic and environmental risk factors. If monozygotic twin concordance is 100%, then the risk is entirely genetic, and the disorder has a single-gene cause. If genotype consistently predicts phenotype, the trait has a single-gene cause, and autosomal-dominant disorders also have a single gene cause.

Question 4

Which statement best explains the &#34;thrifty genotype&#34; for the high incidence of type 2 diabetes?&#10;A)The person with a thrifty genotype has an efficient metabolism that generates more energy from less food and is more likely to survive famine.&#10;B)The person with a thrifty genotype conserves the energy lost from the body as heat and requires less rest to perform the same amount of work.&#10;C)The person with a thrifty genotype stores energy rather than expends energy so that more energy is available for survival when food is scarce.&#10;D)The person with a thrifty genotype feels satiety with smaller amounts of food and is less likely to become obese, thus increasing longevity.

Accepted Answer

During historical times when populations experienced periods of plenty followed by times of famine, those people who were better at storing fat survived to pass on their genes to their offspring. People who were not metabolically "thrifty" would be less able to store fat, and they would not survive during times when there was little food.

Question 5

What can be interpreted about type 2 diabetes mellitus in monozygotic twins when it affects only one twin 70% of the time and affects both twins 30% of the time?&#10;A)The trait is recessive.&#10;B)Mutation repair is incompletely penetrant.&#10;C)Nongenetic factors can influence expression.&#10;D)Homologous genes can undergo chromatid exchanges.

Accepted Answer

Type 2 diabetes mellitus is a complex or multifactorial disorder. Although there is a genetic predisposition, which both members of a set of monozygotic twins would inherit equally, environmental influences (especially obesity and sedentary lifestyle) greatly influence the development of this disease.

Question 6

If a man with hereditary hemochromatosis has children with a woman who is a carrier for the disorder, what is the expected risk pattern?&#10;A)All sons will be affected; all daughters will be carriers.&#10;B)Daughters have a 50% risk for being affected; all sons will either be affected or carriers.&#10;C)Each child of either gender has a 50% risk of being a carrier and a 50% risk of having the disease.&#10;D)Each child of either gender has a 50% risk of being a carrier, a 25% risk of having the disease, and a 25% risk of neither being a carrier nor having the disease.

Accepted Answer

The disease is expressed in an autosomal-recessive pattern of inheritance, and the individual must be homozygous to express the disease. Although males express the disorder at earlier ages than females, both genders are equally expressed. Because the man is homozygous for the mutation, and the woman is heterozygous, any children he fathers have a 4 out of 4 chance (100% risk) to inherit a mutated allele from him. Each child has a 2 out of 4 chance (50% risk) to inherit a mutated allele from the carrier woman. There is no chance for children of this couple to not inherit at least one mutated allele.

Question 7

Why is predictive testing for Huntington disease avoided for a 4-year-old child who has one grandparent with the disorder?&#10;A)Unless one of the parents is positive for the gene mutation, a negative finding would be noninformative.&#10;B)The Huntington disease mutation is poorly penetrant and may never be expressed even when inherited.&#10;C)A 4-year-old child cannot understand or participate in the genetic counseling process.&#10;D)There are no effective primary or secondary prevention strategies for this disorder.

Accepted Answer

The Huntington disease mutation has a high penetrance, which means that a person who inherits the mutation will eventually express the disease. It also means that if a person is negative for this mutation, he or she will never develop this disease. At the present time, there is no way to prevent the disorder in a person who has the mutation. Identifying the child at this age as having the mutation provides no benefit. Although it is true that a child of this age could not understand or participate in the genetic counseling, if treatment was possible, it would be worth performing the test anyway.

Question 8

Why are women usually older than men before symptoms of hereditary hemochromatosis manifest?&#10;A)Women have a counterbalancing normal gene on their second X chromosome.&#10;B)Women lose some iron with normal menstruation during childbearing years.&#10;C)Men have a larger muscle mass and more iron-storing capability than women.&#10;D)Men have greater expression of the gene for hemoglobin than do women.

Accepted Answer

Women with hereditary hemochromatosis do not show signs of iron overload until a later age than men, often not until well after menopause, because the menstrual cycle provides natural and regular blood iron loss every month. The gene for hereditary hemochromatosis is on an autosome, not on the X chromosome.

Question 9

Why do the clinical signs and symptoms of hereditary hemochromatosis not appear until middle adulthood?&#10;A)The adult over 50 has had more exposures to environmental insults over time.&#10;B)Prolonged dietary exposure to toxins produces clinical symptoms.&#10;C)Hereditary hemochromatosis has age-related penetrance.&#10;D)Stored iron builds up over time, causing organ damage.

Accepted Answer

The cause of organ damage and symptoms in hereditary hemochromatosis is the buildup of stored iron over time. This is a single-gene disorder, and environmental factors such as diet and environmental insults do not play a significant role. Hereditary hemochromatosis does not have age-related penetrance.

Question 10

What factors increase the clinical severity of -1 antitrypsin (ATT) deficiency?
1) Whether or not the person smokes
2) Whether or not the person uses alcohol
3) The severity of disease in affected relatives
4) The specific alleles of the genes inherited

A) 1 and 4
B) 2 and 3
C) 2 and 4
D) 4 only

Accepted Answer

Some ATT genotypes (such as the SZ and ZZ genotypes) confer higher risk of clinical disease. Risk for severe disease is increased by smoking, as well as by the specific gene alleles inherited. The severity of disease in relatives and the use of alcohol have not been shown to increase risk.

Question 11

Which type of diabetes has a slow onset and is often diagnosed in North American only when a complication is present?&#10;A)Type 1 diabetes mellitus&#10;B)Type 2 diabetes mellitus&#10;C)Maturity-onset diabetes of the young (MODY)&#10;D)Gestational diabetes mellitus

Accepted Answer

The answer of Which type of diabetes has a slow...

Question 12

What do each of the genes involved in maturity-onset diabetes of the young (MODY) have in common?&#10;A)They are all located on the long arm of chromosome 6.&#10;B)They each play a role in the metabolism of glucose, or insulin action and release.&#10;C)Although they are of different sizes, they all contain the same exon and intron sequences.&#10;D)The genes that cause MODY are expressed only in the young and suppressed during adulthood.

Accepted Answer

The answer of What do each of the genes involved...

Question 13

What is the inheritance pattern for -1 antitrypsin (ATT) deficiency?&#10;A)Autosomal dominant&#10;B)Autosomal recessive&#10;C)Autosomal codominant&#10;D)Sex-linked recessive

Accepted Answer

The answer of What is the inheritance pattern for -1...

Question 14

Which relatively common adult-onset disorder or health problem is the result of a mutation in a single gene?&#10;A)Type 2 diabetes&#10;B)Multiple sclerosis&#10;C)Hereditary hemochromatosis&#10;D)Age-related macular degeneration

Accepted Answer

The answer of Which relatively common adult-onset disorder or health...

Question 15

What is the best definition of the term compound heterozygous?&#10;A)A person who has two different mutated alleles for an autosomal-recessive disorder&#10;B)A person whose expression of an autosomal-recessive disorder is modified by silencing of one allele&#10;C)A person who expresses a genetic disorder having different mutations on two nonhomologous chromosomes&#10;D)A person having a complex disorder in which there is unequal influence of genetic and environmental contributions

Accepted Answer

The answer of What is the best definition of the...

Question 16

Which type of maturity-onset diabetes of the young (MODY) is the most common?&#10;A)MODY-1&#10;B)MODY-2&#10;C)MODY-3&#10;D)MODY-4

Accepted Answer

The answer of Which type of maturity-onset diabetes of the...

Question 17

A 31-year-old man has been diagnosed with chronic obstructive pulmonary disease (COPD) as a result of being homozygous for the ZZ mutation of the -1 antitrypsin (AAT)gene alleles. His wife has been tested and has the MM genotype on her AAT gene alleles. The man is worried that his three children may eventually develop COPD. What is your best response?

A)"Because your wife does not have the mutation, and neither of your parents has the disease, your children will not be affected."
B)"Because your wife is not affected and is not a carrier, your children will have normal levels of AAT, and their risk is the same as for the general population."
C)"Because you have the mutations, and your wife does not, your son will be at an increased risk for developing COPD, but your daughter will only be a carrier."
D)"Because your children will each have only one mutated gene allele, their risk for COPD is primarily dependent on chronic environmental exposure to inhalation irritants."

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Accepted Answer

The answer of A 31-year-old man has been diagnosed with...

Question 18

Your patient's family comes from Ireland. Both her parents are carriers of gene mutations causing hereditary hemochromatosis (HFE-HHC). What is your patient'srisk of having the clinical signs of this disorder?

A)HHC is an autosomal-recessive condition; the risk is 25%.
B)HHC has incomplete penetrance; we cannot accurately predict the clinical risk.
C)HHC is a complex trait; we cannot accurately predict the clinical risk.
D)HHC is an autosomal-dominant trait; the risk is 50%.

Accepted Answer

The answer of Your patient's family comes from Ireland. Both...

Question 19

A fasting blood glucose sample indicates that your 24-year-old male patient has hyperglycemia that was not present during a test 6 weeks ago. What is the mostlikely cause of this?&#10;A)Type 1 diabetes mellitus&#10;B)Type 2 diabetes mellitus&#10;C)Maturity-onset diabetes of the young (MODY)&#10;D)Gestational diabetes mellitus

Accepted Answer

The answer of A fasting blood glucose sample indicates that...

Question 20

Which genetic disorder is associated with an increased risk for type 2 diabetes?&#10;A)Achondroplasia&#10;B)Down syndrome&#10;C)Huntington disease&#10;D)Hereditary hemochromatosis

Accepted Answer

The answer of Which genetic disorder is associated with an...

Question 21

An obese patient (body mass index of 35) states, &#34;There is no point in changing how I eat because it is all genetics anyway.&#34; What is the best response?&#10;A)&#34;Even with a large genetic component, obesity can be reduced through a sensible diet and exercise.&#34;&#10;B)&#34;Let's gather some more family history about body height, weight, and eating patterns.&#34;&#10;C)&#34;You are right; you can't change your genes. There is no point in dieting.&#34;&#10;D)&#34;With your genetics, your best bet would be a low-carb Atkins-type diet.&#34;

Accepted Answer

The answer of An obese patient (body mass index of...

Question 22

Which statement is true regarding age-related macular degeneration (AMD)?&#10;A)It is the most common cause of peripheral vision impairment among the elderly.&#10;B)It is transmitted in an autosomal-recessive pattern of inheritance.&#10;C)Smoking increases the risk in those who are genetically susceptible.&#10;D)Predictive genetic testing can identify the genes that cause AMD.

Accepted Answer

The answer of Which statement is true regarding age-related macular...

Question 23

Which autoimmune disorder has the greatest environmental contribution?&#10;A)Stickler syndrome&#10;B)Rheumatoid arthritis&#10;C)Multiple sclerosis&#10;D)Systemic lupus erythematosus

Accepted Answer

The answer of Which autoimmune disorder has the greatest environmental...

Question 24

Multiple sclerosis is more common in people from what geographic area?&#10;A)Western Africa&#10;B)Southeast Asia&#10;C)Mediterranean region&#10;D)Northern Europe

Accepted Answer

The answer of Multiple sclerosis is more common in people...

Question 25

Which statement regarding autoimmune diseases is true?&#10;A)Autoimmune disorders and diseases are more common among females than among males.&#10;B)Autoimmune disorders and diseases are more common among males than among females.&#10;C)The main characteristics of an autoimmune disorder are a reduced inflammatory response and increased susceptibility to infection.&#10;D)The main characteristics of an autoimmune disorder are an increased inflammatory response and decreased susceptibility to infection.

Accepted Answer

The answer of Which statement regarding autoimmune diseases is true?&#10;A)Autoimmune...

Deck 12: Common Adult-Onset Disorders