Question 1

Which of the following is NOT a criterion recommended by ACOG for including a condition on an expanded carrier screening panel?

Accepted Answer

The disorder must be adult-onset.

Question 2

A 28-year-old woman of Mediterranean descent is pregnant. According to current recommendations, which test should be automatically offered to her to screen for hemoglobinopathies?

Accepted Answer

Hemoglobin electrophoresis

Question 3

Which gene is primarily associated with beta thalassemia, and what is the typical genetic mechanism causing the disorder?

Accepted Answer

HBB gene; point mutations

Question 4

A couple is found to both be carriers for cystic fibrosis. What is the probability that their child will be affected by cystic fibrosis? Use the Hardy-Weinberg principle for a recessive disorder.

Accepted Answer

$$P = 0.25$$

Question 5

Which of the following best explains why cystic fibrosis carrier screening is now recommended for all ethnic groups in the US?

Accepted Answer

Cystic fibrosis occurs in all populations and many individuals have mixed or unknown ancestry.

Question 6

A CBC (complete blood count) is used as a prescreen for hemoglobinopathies. Which two values, if low, prompt follow-up with hemoglobin electrophoresis?

Accepted Answer

Mean corpuscular hemoglobin (MCH) and mean corpuscular volume (MCV)

Question 7

A patient is found to have three deletions among the HBA1 and HBA2 genes. Which clinical scenario is most likely?

Accepted Answer

The patient will have significant symptoms of alpha thalassemia.

Question 8

Which of the following is TRUE regarding sickle cell anemia?

Accepted Answer

It is caused by a specific point mutation in the HBB gene.

Question 9

A woman of Ashkenazi Jewish ancestry is seeking preconception carrier screening. Which of the following disorders should be specifically offered to her, in addition to universal recommendations?

Accepted Answer

Tay-Sachs disease, Canavan disease, familial dysautonomia, and cystic fibrosis

Question 10

Why is it important to identify a patient's ethnicity when considering carrier screening recommendations?

Accepted Answer

Certain genetic disorders have higher prevalence in specific ethnic groups, guiding targeted screening.

Question 11

A couple has no known family history of genetic disorders, but the woman has a low MCV and MCH on her CBC. What is the next best step in carrier screening for hemoglobinopathies?

Accepted Answer

Order a hemoglobin electrophoresis.

Question 12

Which of the following statements about expanded carrier screening panels is CORRECT?

Accepted Answer

They may include hundreds of disorders, but ACOG recommends inclusion only if certain criteria are met.

Question 13

A man is found to be a carrier for beta thalassemia. His partner is not a carrier. What is the probability that their child will be affected by beta thalassemia?

Accepted Answer

$$P = 0$$

Question 14

Which of the following is a reason why disorders like Alzheimer's disease and breast cancer are NOT included in standard carrier screening panels?

Accepted Answer

They are not early-onset and do not have prenatal interventions that improve outcomes.

Question 15

A woman with a family history of intellectual disability in male relatives is being evaluated for carrier screening. Which test is most appropriate to offer her?

Accepted Answer

Fragile X carrier screening

Question 16

If a person has two deletions among the HBA1 and HBA2 genes, what is their likely clinical status?

Accepted Answer

Carrier for alpha thalassemia, possibly with mild symptoms

Question 17

Which of the following best describes the inheritance pattern of spinal muscular atrophy (SMA)?

Accepted Answer

Autosomal recessive

Question 18

A patient of Southeast Asian descent should be specifically screened for which hemoglobinopathy due to increased prevalence in this population?

Accepted Answer

Alpha thalassemia

Question 19

Which of the following scenarios would most likely prompt carrier screening for fragile X syndrome in a woman?

Accepted Answer

Family history of intellectual disability or features suggestive of fragile X

Question 20

A couple is considering expanded carrier screening. Which of the following best describes the minimum carrier frequency for a disorder to be considered, according to ACOG recommendations?

Accepted Answer

$$f_{carrier} \u003e \frac{1}{100}$$

Population-Based Carrier Screening in Clinical Genetics

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