Ch 05

Question 1

What is the definition of incidence rate?

Number of new cases of a disease reported during a specific period, divided by the number of individuals in the population 
Proportion of the population affected by a disease at a specific point in time
The effect of a specific risk factor
Variation is caused by the multiple effects of genes.

Answer 1

Number of new cases of a disease reported during a specific period, divided by the number of individuals in the population

The number of new cases of a disease reported during a specific period of time (typically 1 year), divided by the number of individuals in the population, is the incidence rate. The proportion of the population affected by a disease at a specific point in time is the prevalence rate. The effect of a specific risk factor is the relative risk. Polygenic genes cause variation.

Question 2

Which statement is true regarding the risks of developing a disease?

Empiric risks are based on assumptions. 
Recurrence risk is higher if more than one family member is affected. 
An individual below the threshold of liability for a disease will have the disease.
The recurrence risk for disease usually increases rapidly in more remotely related relatives.

Answer 2

Recurrence risk is higher if more than one family member is affected

Recurrence risk is higher if more than one family member is affected and usually decreases rapidly in more remotely related relatives. Empiric risks are based on observation. For diseases that have a threshold of liability, an individual usually does not have the disease below the threshold of liability.

Question 3

Which statement describes a monozygotic twin?

Twins who share very few traits 
Twins who share all traits 
Twins who form from double ovulation
Twins whose rates vary among populations 

Monozygotic twins divide from one embryo and actually share traits. They are natural clones. Twins from double ovulation are dizygotic and may not share traits. Monozygotic twins have the same rate across populations. Dizygotic or fraternal rates vary among populations.

Answer 3

Twins who share all traits

Monozygotic twins divide from one embryo and actually share traits. They are natural clones. Twins from double ovulation are dizygotic and may not share traits. Monozygotic twins have the same rate across populations. Dizygotic or fraternal rates vary among populations.

Question 4

Which statement regarding coronary heart disease is true?

It is the leading killer of Americans. 
Atherosclerosis causes widening of the blood vessels.
CHD is more common in women.
The relative risk for CHD does not increase with relatives affected.

Answer 4

It is the leading killer of Americans

Coronary heart disease is the leading killer of Americans. Narrowing of blood vessels occurs as a result of atherosclerosis. Men are more commonly affected. Relative risk increases when two or more relatives are affected before the age 55 years.

Question 5

Which statement regarding hypertension is true?

Systemic hypertension is observed in less than 5% of populations. 
Environmental factors do not cause hypertension.
One of the most important factors affecting blood pressure is sodium intake. 
A 100% correlation exists among family members and blood pressure.

Answer 5

One of the most important factors affecting blood pressure is sodium intake.

Sodium intake, obesity, decreased physical activity, and psychosocial stress are important environmental risk factors for obesity. Systemic hypertension affects approximately 25% to 30% of the population. Only a 20% to 40% correlation exists among family members.

Question 6

Which gene is linked with breast cancer?

BRCA1 
APC
HLA II
IDDM

Answer 6

BRCA1

BRCA1 is located on chromosome 17, and BRCA2 is located on chromosome 13. If women inherit these genes, then their lifetime risk of getting breast cancer increases by 50% to 80%. The APC gene is associated with colon cancer. Human leukocyte antigen (HLA) II is associated with diabetes. IDDM stands for insulin-dependent diabetes mellitus.

Question 7

Which statement is true regarding type II diabetes?

Type II diabetes accounts for fewer than 10% of all cases of diabetes. 
Pancreatic insulin is not produced.
These individuals experience insulin resistance. 
Type II diabetes is less common among obese persons. 

Type II diabetes is responsible for more than 90% of all cases of diabetes. Usually people who develop type II diabetes are older than 40 years of age and are obese. They produce insulin and have insulin resistance.

Answer 7

These individuals experience insulin resistance.

Type II diabetes is responsible for more than 90% of all cases of diabetes. Usually people who develop type II diabetes are older than 40 years of age and are obese. They produce insulin and have insulin resistance.

Question 8

Which statement is true regarding Alzheimer disease?

Alzheimer disease affects 40% of the population older than 65 years of age. 
Alzheimer disease is characterized by progressive dementia and memory loss. 
It has one gene locus.
Antidiuretic hormone is a key factor.

Answer 8

Alzheimer disease is characterized by progressive dementia and memory loss.

Alzheimer disease affects approximately 5% to 10% of the population, age 65 years and older. It is characterized by progressive dementia and memory loss. There are multiple gene loci with three being identified. ADH is aldehyde dehydrogenase, which is responsible for alcohol metabolism.

Question 9

Which are congenital diseases in infants? (Select all that apply.)

Cleft lip 
Clubfoot 
Hydrocephaly 
Obesity

Answer 9

Cleft lip
Clubfoot
Hydrocephaly

Although people are born with factors that may cause obesity, infants are not born with this condition present. All of the other choices are traits that are present at birth.

Question 10

Which statement is true regarding alcoholism? (Select all that apply.)

Alcoholism is more prevalent in females than males. 
Individuals with the ALDH2*2 gene are less likely to become alcoholics. 
Alcoholism clusters in families. 
Alcoholism requires an environmental component.

Answer 10

Individuals with the ALDH2*2 gene are less likely to become alcoholics.
Alcoholism clusters in families.
Alcoholism requires an environmental component.

An allele of the ALDH2 gene (ALDH22) results in excessive accumulation of acetaldehyde and thus in facial flushing, nausea, palpitations, and lightheadedness. Because of these unpleasant effects, individuals who have the ALDH22 allele are much less likely to become alcoholics. More than 100 studies have shown that alcoholism clusters in families. Genes increase one’s susceptibility to alcoholism, which means that alcoholism requires an environmental component, regardless of genetic constitution. Alcoholism is diagnosed in approximately 10% of adult males and 3% to 5% of adult females in the United States.

Question 11

A community health APRN is analyzing data on type 2 diabetes in a rural population. The report states that 150 new cases were diagnosed last year in a population of 10,000 at risk. Which measure best describes this finding, and how is it calculated?

A) Prevalence rate: Total affected individuals divided by the population at a point in time.
B) Relative risk: Incidence in exposed divided by incidence in unexposed.
C) Incidence rate: Number of new cases over a period divided by the population at risk.
D) Recurrence risk: Square root of population prevalence for multifactorial traits.

Answer 11

C) Incidence rate: Number of new cases over a period divided by the population at risk.

Rationale: Incidence rate is the high-yield measure for new cases (150/10,000 = 1.5%), tracking onset in populations for multifactorial diseases like type 2 diabetes. Trap A confuses with prevalence (point-in-time burden, not new cases). Trap B misapplies relative risk (compares exposures, not raw rate). Trap D borrows multifactorial recurrence approximation (√f) but applies it wrongly to incidence.

Question 12

An APRN counsels a family where the proband (a male infant) has pyloric stenosis, a multifactorial disorder. The parents ask about recurrence risk in future children. Based on principles of multifactorial inheritance, which factor would most likely increase the risk?

A) The disorder following a 50% Mendelian recessive pattern in siblings.
B) The proband being from the more commonly affected sex.
C) Multiple affected relatives, shifting the liability threshold leftward.
D) The disease severity being mild, indicating lower genetic loading.

Answer 12

C) Multiple affected relatives, shifting the liability threshold leftward.

Rationale: In multifactorial inheritance, recurrence risk rises with multiple affected relatives due to higher familial genetic loading, shifting the liability distribution (high-yield threshold model). Trap A applies Mendelian probability incorrectly (multifactorial doesn’t follow simple ratios). Trap B reverses the sex effect (pyloric stenosis more common in males; less-common sex proband increases risk). Trap D inverts severity (milder = lower risk; severe indicates higher loading).

Question 13

During a graduate seminar, an APRN student explains the liability threshold model for quantitative traits like blood pressure leading to hypertension. Which statement accurately reflects this high-yield concept?

A) The population distribution is skewed left for affected individuals, with disease only below the threshold.
B) Liability combines genetic and environmental factors; disease manifests when it exceeds the threshold.
C) Quantitative traits always follow a bimodal distribution in multifactorial diseases.
D) The threshold is fixed across populations, unaffected by gene frequencies or environment.

Answer 13

B) Liability combines genetic and environmental factors; disease manifests when it exceeds the threshold.

Rationale: The liability threshold is the core model where additive genetic + environmental liability must cross a threshold for manifestation (bell-shaped to right-shift in affected). Trap A reverses direction (affected shift right, not left; exceeds, not below). Trap C confuses with single-gene (bimodal rare; multifactorial normal/bell-shaped). Trap D ignores population variability (thresholds vary by gene-environment differences).

Question 14

An APRN evaluates a patient with a family history of schizophrenia. The proband (patient’s sibling) has severe symptoms. What high-yield criterion from multifactorial inheritance principles would elevate recurrence risk for the patient’s offspring?

A) The proband’s mild expression, suggesting environmental dominance.
B) Risk decreasing with closer relatives, like first-degree.
C) The proband’s severe expression, indicating higher genetic loading.
D) Exact 25% risk based on Mendelian dominant pattern.

Answer 14

Correct Answer: C) The proband’s severe expression, indicating higher genetic loading.

Rationale: Severity in the proband raises recurrence risk in multifactorial diseases, reflecting proximity to threshold and stronger genetics (high-yield criterion). Trap A inverts severity (mild = lower risk). Trap B reverses relation (risk higher in closer relatives; decreases with distance). Trap D applies Mendelian probability (multifactorial uses empirical risks, not fixed %).

Question 15

An APRN reviews research on type 2 diabetes, a multifactorial disease. A study shows 80% concordance in monozygotic (MZ) twins and 30% in dizygotic (DZ) twins. What does this high-yield finding primarily indicate?

A) Strong environmental influence, as DZ concordance is lower than MZ.
B) Purely genetic causation, since MZ share 100% genes.
C) Relative genetic and environmental contributions, with higher MZ highlighting genetics.
D) No role for genes, as concordance isn’t 100% in MZ.

Answer 15

C) Relative genetic and environmental contributions, with higher MZ highlighting genetics.

Rationale: Twin studies disentangle nature/nurture; higher MZ vs. DZ concordance supports genetic influence in multifactorial diseases, but <100% indicates environment (high-yield for type 2 DM). Trap A flips interpretation (lower DZ supports genetics when MZ higher). Trap B overstates (not purely genetic; environment interacts). Trap D understates (imperfect concordance shows both factors).

Question 16

In counseling a patient adopted at birth with a biological family history of bipolar disorder, an APRN uses adoption study evidence. If the patient resembles adoptive relatives in mood traits, what does this high-yield imply?

A) Strong genetic influence from biological family.
B) Environmental factors from adoptive setting predominant.
C) Purely genetic, as adoption separates environments.
D) No environmental role, confirming multifactorial genetics.

Answer 16

B) Environmental factors from adoptive setting predominant.

Rationale: Adoption studies show adoptive resemblance indicates environment (high-yield for disentangling; e.g., bipolar). Trap A reverses (biological resemblance = genetic). Trap C assumes perfect separation (adoptions highlight but don’t eliminate interactions). Trap D ignores nurture (most multifactorial involve both).

Question 17

A 50-year-old patient with obesity and family clustering of colon cancer asks an APRN about etiology. Which statement best applies high-yield knowledge of common multifactorial diseases?

A) It’s single-gene Mendelian, like cystic fibrosis, with 50% sibling risk.
B) Genetic component means the course is unalterable, no lifestyle role.
C) Polygenic + environmental (diet, inactivity) interactions drive it.
D) Empirical risks are irrelevant; use precise gene sequencing for counseling.

Answer 17

C) Polygenic + environmental (diet, inactivity) interactions drive it.

Rationale: Colon cancer is a high-yield adult multifactorial disease with gene-environment interplay (modifiable lifestyle). Trap A misclassifies as single-gene (multifactorial no Mendelian ratios). Trap B ignores modifiability (boards emphasize alteration via environment). Trap D over-relies on testing (empirical risks guide multifactorial counseling).

Question 18

An APRN educates a patient with genetic predisposition to hypertension about management. Based on high-yield gene-environment principles, what is the most accurate advice?

A) Genetics predetermine outcome; focus solely on medications.
B) Environment (diet, exercise) can alter course despite genetic risk.
C) Liability threshold is irrelevant; treat as single-gene disorder.
D) Recurrence risk is fixed at √f, ignoring lifestyle.

Answer 18

B) Environment (diet, exercise) can alter course despite genetic risk.

Rationale: High-yield: Genetic components don’t make diseases unalterable; modifiable environment (nurture) interacts (e.g., hypertension). Trap A over-emphasizes genetics (ignores interplay). Trap C confuses models (threshold key to multifactorial). Trap D misapplies recurrence (empirical, but lifestyle modifies).

Question 19

An APRN takes a 3-generation family history revealing early-onset stroke in multiple relatives. For this multifactorial disease, what high-yield action is priority?

A) Order single-gene testing, assuming Mendelian pattern.
B) Counsel using empirical risks, emphasizing modifiable factors like smoking.
C) Reassure no increased risk, as not all relatives affected.
D) Ignore environment; focus on unalterable genetic counseling.

Answer 19

B) Counsel using empirical risks, emphasizing modifiable factors like smoking.

Rationale: Family history red flags (clustering) indicate multifactorial risk; use empirical data for counseling, stress modifiability (high-yield APRN role). Trap A assumes Mendelian (not for stroke). Trap C misses clustering (increases risk). Trap D ignores nurture (environment alters).

Question 20

A patient with schizophrenia history in biological parents, but raised in a low-stress adoptive home, remains unaffected. What high-yield concept from chapter principles explains this?

A) Pure genetics: Should be affected regardless of environment.
B) Mendelian: 25% risk not manifesting by chance.
C) Gene-environment interaction: Predisposition without triggers prevents crossing threshold.
D) Twin concordance irrelevant; adoption proves environment alone.

Answer 20

C) Gene-environment interaction: Predisposition without triggers prevents crossing threshold.

Rationale: Schizophrenia is multifactorial; genetics + environment (e.g., stress) needed to exceed threshold (high-yield interaction). Trap A overstates genetics (requires triggers). Trap B applies Mendelian wrongly. Trap D overstates environment (adoption shows both).