Q: Suppose a DNA-based screening program is implemented in a population where 2% of individuals carry a pathogenic variant for HBOC, Lynch syndrome, or familial hypercholesterolemia. If the population size is 1,000,000, how many individuals are expected to carry such a variant?

$$2\% \times 1,000,000 = 20,000$$

Question 1

Which of the following is a key reason why medical history–based screening for monogenic risk often fails to identify the majority of individuals at risk for cancer and heart disease?

Accepted Answer

Medical history–based screening is time-intensive and has limited sensitivity.

Question 2

According to the article, which of the following genetic conditions is NOT currently included in the CDC's tier-1 genomic applications for population screening?

Accepted Answer

Sickle cell anemia

Question 3

A population-based DNA screening program identifies a group of individuals with pathogenic variants in BRCA1/2. Which of the following statements best describes the expected outcome for these individuals?

Accepted Answer

Some individuals will develop cancer, but not all, due to incomplete penetrance.

Question 4

Which of the following is a major challenge in interpreting DNA variants for population screening?

Accepted Answer

Most DNA variants are classified as 'variants of unknown significance' due to insufficient evidence.

Question 5

Suppose a DNA-based screening program is implemented in a population where 2% of individuals carry a pathogenic variant for HBOC, Lynch syndrome, or familial hypercholesterolemia. If the population size is 1,000,000, how many individuals are expected to carry such a variant?

Accepted Answer

$$2\% 	imes 1,000,000 = 20,000$$

Question 6

Which of the following best explains why blood pressure measurement is widely accepted as a population screening tool, according to the article?

Accepted Answer

It fulfills five key principles, including easy detection, clear interpretation, effective interventions, documented benefits, and lack of better alternatives.

Question 7

A health system screens 50,000 adults for BRCA1/2 variants and finds that only 18% of those with pathogenic variants were previously aware of their status. What does this finding suggest about the sensitivity of medical history–based screening?

Accepted Answer

It has low sensitivity and misses the majority of at-risk individuals.

Question 8

Which of the following is a limitation of current DNA-based population screening highlighted in the article?

Accepted Answer

Long-term clinical and economic outcomes for individuals identified solely by DNA-based screening are not yet well established.

Question 9

If a variant is classified as a 'variant of unknown significance' (VUS), what is the recommended approach in population screening?

Accepted Answer

Set aside the variant until more evidence is available to support its classification.

Question 10

Which of the following best describes the concept of 'penetrance' as used in the context of DNA-based population screening?

Accepted Answer

The proportion of individuals with a pathogenic variant who develop the associated disease.

Question 11

A new DNA-based screening test is proposed for a rare cancer where nearly 100% of cases are associated with a known pathogenic variant. Which of the following is most likely true about the utility of DNA-based screening for this cancer?

Accepted Answer

DNA-based screening would likely be highly effective in identifying at-risk individuals.

Question 12

Which of the following is a critical evidence gap that must be addressed before routine DNA-based population screening can be implemented?

Accepted Answer

The effectiveness of interventions in individuals identified by DNA-based screening who do not meet medical history–based thresholds.

Question 13

If the prevalence of HBOC, Lynch syndrome, and familial hypercholesterolemia combined is 1.5% in the US population, and the US population is approximately 330 million, estimate the number of individuals with one of these risks.

Accepted Answer

$$0.015 	imes 330,000,000 = 4,950,000$$

Question 14

Which of the following is a reason why defining 'normal' in DNA-based screening is challenging?

Accepted Answer

Existing data sets underrepresent non-European populations.

Question 15

Which of the following best describes the current role of ClinVar in DNA-based population screening?

Accepted Answer

It is a database that holds evidence regarding the pathogenicity of human genetic variants.

Question 16

A patient is found to have a pathogenic variant in the LDLR gene through DNA-based screening. Which condition is this patient at increased risk for?

Accepted Answer

Familial hypercholesterolemia

Question 17

Which of the following is a potential advantage of DNA-based population screening over medical history–based screening?

Accepted Answer

It can identify individuals with pathogenic variants regardless of family history.

Question 18

Why is it important to conduct large pilot studies before implementing routine DNA-based population screening?

Accepted Answer

To gather evidence on clinical utility and economic feasibility.

Question 19

Which of the following interventions may be recommended for individuals identified with monogenic risk for HBOC, Lynch syndrome, or familial hypercholesterolemia?

Accepted Answer

Enhanced screening, risk-reducing medications, and prophylactic surgery

Question 20

Which of the following statements about the evolution of screening for treatable hypertension is supported by the article?

Accepted Answer

Interventions for hypertension were initially controversial and evolved with research.

DNA-Based Population Screening: Principles, Suitability, and Knowledge Gaps

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