WBR0139
| Author | [[PageAuthor::Rim Halaby, M.D. [1](Reviewed by Alison Leibowitz), William J Gibson]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Embryology |
| Sub Category | SubCategory::Cardiology |
| Prompt | [[Prompt::A 9-year-old male patient is brought to the ER with complaints of recurring infections. Upon physical examination you observe that the patient has low set ears and eyes that appear abnormally far apart. The patient is underweight with a BMI of 13.5 and upon further questioning you learn that, from a young age, he has experienced difficulty gaining weight. Laboratory results indicate that the patient has a deletion in chromosome 22. Of the following embryological structures, which would most likely form abnormally in individuals who have the same chromosomal abnormality as the patient described in this scenario?]] |
| Answer A | AnswerA::Truncus arteriosus |
| Answer A Explanation | [[AnswerAExp::The patient in this scenario presents with findings characteristic of DiGeorge syndrome. DiGeorge syndrome is characterized by the deletion of 22q11.2. Deletions on chromosome 22 often manifest with defects in neural crest migration. The truncus arteriosus, which gives rise to the ascending aorta and the pulmonary trunk, often forms abnormally in patients with DiGeorge syndrome, leading to the additional diagnosis of persistent truncus arteriosus, which is caused by the deletion in chromosome 22q11.2.]] |
| Answer B | AnswerB::Bulbus cordis |
| Answer B Explanation | [[AnswerBExp::The Bulbus cordis, which gives rise to the right ventricle and the smooth part of the left ventricle, is not associated with DiGeorge syndrome.]] |
| Answer C | AnswerC::Sinus venosum |
| Answer C Explanation | [[AnswerCExp::The sinus venosum gives rise to the coronary sinus.]] |
| Answer D | AnswerD::Third aortic arch |
| Answer D Explanation | [[AnswerDExp::The third aortic arch, which gives rise to to the common carotid artery and the proximal part of the internal carotid artery, is not associated with DiGeorge syndrome.]] |
| Answer E | AnswerE::Fourth aortic arch |
| Answer E Explanation | [[AnswerEExp::The fourth aortic arch, which gives rise to the proximal part of the right subclavian artery is not associated with DiGeorge syndrome.]] |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::The patient in this scenario presents with findings characteristic of DiGeorge syndrome. DiGeorge syndrome is characterized by the deletion of chromosome 22q11.2. Deletions on chromosome 22 often manifest with defects in neural crest migration. The truncus arteriosus, which gives rise to the ascending aorta and the pulmonary trunk, often forms abnormally in patients with DiGeorge syndrome, due to dysfunction of cardiac neural crest cells. These patients develop persistent truncus arteriosus, a condition in which the aorticopulmonary septum has not formed (pictured below). Oxygenated blood from the left ventricle mixes with deoxygenated blood from the right and is pumped into the both the lungs and systemic circulation through one great vessel. These children are cyanotic at birth and require surgical intervention.
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| Approved | Approved::Yes |
| Keyword | WBRKeyword::Cardiology, WBRKeyword::Embrology, WBRKeyword::Congenital, WBRKeyword::Genetics, WBRKeyword::Neural crest |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |
