Genetic and Metabolic Disorders Practice Questions

Question 1

A 28-year-old woman comes to the physician for genetic counseling prior to conception. For the past year, she has had intermittent episodes of headache, nausea, abdominal pain, and tingling of her fingers. She also complains of dark urine during the episodes. Her mother and maternal uncle have similar symptoms and her father is healthy. Her husband is healthy and there is no history of serious illness in his family. Serum studies show elevated concentrations of porphobilinogen and δ-aminolevulinic acid. What is the probability of this patient having a child with the same disease as her?

Accepted Answer

50%

Answer

25%

Answer

67%

Answer

100%

Question 2

A 25-year-old man with a genetic disorder presents for genetic counseling because he is concerned about the risk that any children he has will have the same disease as himself. Specifically, since childhood he has had difficulty breathing requiring bronchodilators, inhaled corticosteroids, and chest physiotherapy. He has also had diarrhea and malabsorption requiring enzyme replacement therapy. If his wife comes from a population where 1 in 10,000 people are affected by this same disorder, which of the following best represents the likelihood a child would be affected as well?

Accepted Answer

1%

Answer

0.01%

Answer

2%

Answer

0.5%

Answer

50%

Question 3

A 30-year-old man is brought into the emergency room for complaints of acute onset chest pain and shortness of breath. He has a history of mental retardation and lives at home with his adoptive parents. His parents inform you that he has not seen a doctor since he was adopted as child and that he currently takes no medications. The patient's temperature is 99.1°F (37.3°C), pulse is 108/min, blood pressure is 125/70 mmHg, respirations are 25/min, and oxygen saturation is 92% on 2L nasal cannula. Physical exam is notable for a tall, thin individual with high-arched feet and mild pectus excavatum. There is mild asymmetry in the lower extremities with discomfort to dorsiflexion of the larger leg. Lung auscultation reveals no abnormalities. What is the most appropriate next step in management?

Accepted Answer

Electrocardiogram

Answer

Chest radiograph

Answer

Serum blood test

Answer

Genetic testing

Answer

Angiogram

Question 4

A deficiency in which of the following lysosomal enzymes is inherited in a pattern similar to a deficiency of iduronate sulfatase (Hunter syndrome)?

Accepted Answer

Alpha-galactosidase A

Answer

Sphingomyelinase

Answer

Glucocerebrosidase

Answer

Galactocerebrosidase

Answer

Alpha-L-iduronidase

Question 5

A 9-year-old boy is brought to the physician because his parents are concerned that he has been unable to keep up with his classmates at school. He is at the 4th percentile for height and at the 15th percentile for weight. Physical examination shows dysmorphic facial features. Psychologic testing shows impaired intellectual and adaptive functions. Genetic analysis shows a deletion of the long arm of chromosome 7. Which of the following is the most likely additional finding in this patient?

Accepted Answer

Supravalvular aortic stenosis

Answer

Absent thymus gland

Answer

Brushfield spots on the iris

Answer

Testicular enlargement

Answer

Hand flapping movements

Question 6

An 8-year-old child with “elfin” facial features is very friendly with strangers. He has a history of mild mental retardation, and a hemizygous deletion on chromosome 7q11.23, that includes a portion of the elastin gene. Which of the following is most likely true in this patient?

Accepted Answer

Symptoms may develop secondary to left ventricular outflow tract obstruction

Answer

Vitamin D supplementation is recommended

Answer

This patient is less likely to experience angina

Answer

Holosystolic murmur heard at the apex with radiation to the axilla

Answer

Carpopedal spasm induced by sphygmomanometer inflation

Question 7

A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?

Accepted Answer

"Can you tell me more about the symptoms you have been experiencing?"

Answer

"Does the diarrhea typically precede the constipation, or vice-versa?"

Answer

"Is the diarrhea foul-smelling?"

Answer

"Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"

Answer

"Are the symptoms worse in the morning or at night?"

Question 8

A 9-month-old female is brought to the emergency department after experiencing a seizure. She was born at home and was normal at birth according to her parents. Since then, they have noticed that she does not appear to be achieving developmental milestones as quickly as her siblings, and often appears lethargic. Physical exam reveals microcephaly, very light pigmentation (as compared to her family), and a "musty" body odor. The varied manifestations of this disease can most likely be attributed to which of the following genetic principles?

Accepted Answer

Pleiotropy

Answer

Incomplete penetrance

Answer

Multiple gene mutations

Answer

Anticipation

Answer

Variable expressivity

Question 9

A 51-year-old man presents to his physician with decreased libido and inability to achieve an erection. He also reports poor sleep, loss of pleasure to do his job, and depressed mood. His symptoms started a year ago, soon after his wife got into the car accident. She survived and recovered with the minimal deficit, but the patient still feels guilty due to this case. The patient was diagnosed with diabetes 6 months ago, but he does not take any medications for it. He denies any other conditions. His weight is 105 kg (231.5 lb), his height is 172 cm (5 ft 7 in), and his waist circumference is 106 cm. The blood pressure is 150/90 mm Hg, and the heart rate is 73/min. The physical examination only shows increased adiposity. Which of the following tests is specifically intended to distinguish between the organic and psychogenic cause of the patient’s condition?

Accepted Answer

Penile tumescence testing

Answer

Angiography

Answer

Duplex ultrasound of the penis

Answer

Biothesiometry

Answer

Injection of prostaglandin E1

Question 10

A 22-year-old man presents to the emergency department with anxiety. The patient states that he is very anxious and has not been able to take his home anxiety medications. He is requesting to have his home medications administered. The patient has a past medical history of anxiety and depression. His current medications include clonazepam, amitriptyline, and lorazepam. Notably, the patient has multiple psychiatric providers who currently care for him. His temperature is 99.2°F (37.3°C), blood pressure is 130/85 mmHg, pulse is 112/min, respirations are 22/min, and oxygen saturation is 100% on room air. Physical exam is notable for an anxious, sweating, and tremulous young man who becomes more confused during his stay in the emergency department. Which of the following should be given to this patient?

Accepted Answer

Diazepam

Answer

Sodium bicarbonate

Answer

Flumazenil

Answer

Supportive therapy and monitoring

Answer

Midazolam

Genetic and Metabolic Disorders

Study Resources

Lessons

Questions

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Chromosomal Disorders

Disorders of Amino Acid Metabolism

Disorders of Carbohydrate Metabolism

Disorders of Lipid Metabolism

Genetic Counseling

Genetic Testing in Pediatrics

Inborn Errors of Metabolism

Lysosomal Storage Diseases

Mitochondrial Disorders

Multifactorial Inheritance Disorders

Newborn Screening

Single Gene Disorders

Practice Questions

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About Genetic and Metabolic Disorders for USMLE

Lessons in Genetic and Metabolic Disorders

Master Genetic and Metabolic Disorders