Welcome to MedSmarter’s USMLE Style Question Break Down of the Week. For those preparing for the USMLE Step 1, this week we break down a high-yield Immunology question. As always you want to begin with reading the last sentence of the vignette first to get an understanding of what the question is asking for.
Question Break Down of the Week:
A 10-year-old female is brought to the pediatrician by her parents because of a low-grade fever. The physician notes that the girl has featured pale skin and bright blue eyes, which the mother states have been present since birth. The physician diagnoses the girl with a staphylococcal infection and prescribes a course of antibiotics. Three months later, the child returns to the pediatrician with fever and a sore throat, which was diagnosed as a streptococcal infection. A review of the patient’s medical records indicates that she has had repeated episodes of staphylococcal and streptococcal infections for her entire life. This patient most likely has which of the following types of immune deficiency?
A) Chédiak-Higashi disease
B) Chronic granulomatous disease
C) Hyper-IgM syndrome
D) Selective IgA deficiency
E) Severe combined immunodeficiency
The correct answer choice is A: Chédiak-Higashi disease is an inherited autosomal recessive disease. It is caused by a deficiency in lysosomal emptying of phagocytic cells due to a defect in microtubular function. Therefore, patients with Chédiak-Higashi disease often present with recurrent streptococcal and staphylococcal infections. Partial albinism may be present, as melanosomes are derivatives of lysosomes.
Did you think the answer was different?
Did you think that the correct answer choice was other than A? You can view this video for a deeper discussion of why B, C, D, and E were not the correct answer choices.
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