JAK-STAT pathway — MCQs

A 2-year-old girl presents to the pediatrician with an itchy rash. Her mother reports that she has had a crusty rash on the face and bilateral upper extremities intermittently for the past 2 months. The child's past medical history is notable for 3 similar episodes of severely itchy rashes since birth. She has also had 2 non-inflamed abscesses on her arms over the past year. Her temperature is 98.9°F (37.2°C), blood pressure is 108/68 mmHg, pulse is 94/min, and respirations are 18/min. On exam, she appears uncomfortable and is constantly itching her face and arms. There is an eczematous rash on the face and bilateral upper extremities. Her face has thickened skin with a wide-set nose. This patient's condition is most likely caused by a mutation in which of the following genes?

A research team develops a new monoclonal antibody checkpoint inhibitor for advanced melanoma that has shown promise in animal studies as well as high efficacy and low toxicity in early phase human clinical trials. The research team would now like to compare this drug to existing standard of care immunotherapy for advanced melanoma. The research team decides to conduct a non-randomized study where the novel drug will be offered to patients who are deemed to be at risk for toxicity with the current standard of care immunotherapy, while patients without such risk factors will receive the standard treatment. Which of the following best describes the level of evidence that this study can offer?

A 70-year-old man presents to his physician for evaluation of fullness and swelling of the left side of the abdomen over the last month. During this time, he has had night sweats and lost 2 kg (4.4 lb) unintentionally. He has no history of severe illness and takes no medications. The vital signs include: blood pressure 115/75 mm Hg, pulse 75/min, and temperature 36.8℃ (98.2℉). The abdomen has asymmetric distention. Percussion and palpation of the left upper quadrant reveal splenomegaly. No lymphadenopathy is detected. Heart and lung examination shows no abnormalities. The laboratory studies show the following: Hemoglobin 9.5 g/dL Mean corpuscular volume 95 μm3 Leukocyte count 8,000/mm3 Platelet count 240,000/mm3 Ultrasound shows a spleen size of 15 cm, mild hepatomegaly, and mild ascites. The peripheral blood smear shows teardrop-shaped and nucleated red blood cells (RBCs) and immature myeloid cells. Marrow is very difficult to aspirate but reveals hyperplasia of all 3 lineages. The tartrate-resistant acid phosphatase (TRAP) test is negative. The cytogenetic analysis is negative for translocation between chromosomes 9 and 22. Which of the following laboratory findings is most likely to be present in this patient?

A 10-year-old boy from Sri Lanka suffers from an autosomal dominant condition, the hallmark of which is hyperimmunoglobulinemia E and eosinophilia. He suffers from recurrent infections and takes antibiotic chemoprophylaxis. A STAT3 mutation analysis has been performed to confirm the diagnosis of Job syndrome. I. Eosinophilia II. Eczema III. Hay fever IV. Atopic dermatitis V. Recurrent skin and lung infections VI. Bronchial asthma What combination of symptoms above is characteristic of this condition?

A 55-year-old man comes to the physician with a 3-month history of headache, periodic loss of vision, and easy bruising. Physical examination shows splenomegaly. His hemoglobin concentration is 13.8 g/dL, leukocyte count is 8000/mm3, and platelet count is 995,000/mm3. Bone marrow biopsy shows markedly increased megakaryocytes with hyperlobulated nuclei. Genetic analysis shows upregulation of the JAK-STAT genes. The pathway encoded by these genes is also physiologically responsible for signal transmission of which of the following hormones?

A 62-year-old man, a retired oil pipeline engineer, presents to his primary care physician with complaints of headaches, fatigue, and constant ringing in his ears. Recurrently he has developed pruritus, usually after a hot shower. He also noted a constant burning sensation in his fingers and toes, independent of physical activity. On examination, he has a red face and his blood pressure levels are 147/89 mm Hg. A CBC revealed that his Hb is 19.0 g/dL and Hct is 59%. Because of his condition, his physician prescribes him 81 mg of aspirin to be taken daily in addition to therapeutic phlebotomy. Which of the statements below is true about this patient’s condition?

A 65-year-old man comes to the physician because of a 6-month history of progressive fatigue and abdominal pain. Physical examination shows pale mucous membranes and splenomegaly. Hemoglobin concentration is 9.1 g/dL and leukocyte count is 3,400/mm3. Peripheral blood smear shows nucleated red blood cells and teardrop poikilocytosis. A Janus kinase 2 gene mutation is present. Which of the following is the most likely underlying mechanism of this patient's condition?

An epidemiologist is evaluating the efficacy of Noxbinle in preventing HCC deaths at the population level. A clinical trial shows that over 5 years, the mortality rate from HCC was 25% in the control group and 15% in patients treated with Noxbinle 100 mg daily. Based on this data, how many patients need to be treated with Noxbinle 100 mg to prevent, on average, one death from HCC?

An 8-year-old boy presents with recurrent infections including multiple episodes of pneumonia and diarrhea. He reports difficulty seeing in the dark. Physical examination reveals white patches on the sclera and conjunctival dryness. What is the most likely cause of these findings?

An 11-month-old boy is brought to a pediatrician by his parents with a recurrent cough, which he has had since the age of 2 months. He has required 3 hospitalizations for severe wheezing episodes. His mother also mentions that he often has diarrhea. The boy’s detailed history reveals that he required hospitalization for meconium ileus during the neonatal period. Upon physical examination, his temperature is 37.0°C (98.6ºF), pulse rate is 104/min, respiratory rate is 40/min, and blood pressure is 55/33 mm Hg. An examination of the boy’s respiratory system reveals the presence of bilateral wheezing and scattered crepitations. An examination of his cardiovascular system does not reveal any abnormality. His length is 67.3 cm (26.5 in) and weight is 15 kg (33 lbs). His sweat chloride level is 74 mmol/L. His genetic evaluation confirms that he has an autosomal recessive disorder resulting in a dysfunctional membrane-bound protein. Which of the following best describes the mechanism associated with the most common mutation that causes this disorder?