WBR0104

Author	PageAuthor::William J Gibson
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Genetics
Sub Category	SubCategory::Renal
Prompt	[[Prompt::A 40 year old woman with a history of recurrent urinary tract infections presents to her primary care physician with the gradual onset of increasing fatigue, swelling in her feet and anorexia. She reports flank pain, and a recent decrease in urine volume. Her pulse is 76, blood pressure is 145/110 and she has a respiratory rate of 16. Physical exam is remarkable for bilateral solid masses that can be palpated during abdominal examination. Tapping the lower back elicits sharp pain. Laboratory studies are significant a creatinine of 2.3, and BUN of 20. Which of the following is most likely true regarding the patient’s condition?]]
Answer A	AnswerA::Caused by a defect in a calcium channel gene
Answer A Explanation	AnswerAExp::ADPKD2 is caused by defects in a calcium channel gene. ADPKD2 has a later onset and is rarer than ADPKD1 mutations.
Answer B	AnswerB::Caused by a defect in the assembly of the cilium
Answer B Explanation	AnswerBExp::This patient's form of ADPKD caused by ADPKD1 mutations. ADPKD1 is thought to encode a cellular membrane protein involved in assembly of the cilium.
Answer C	AnswerC::Caused by autoantibodies against glomerular basement membrane
Answer C Explanation	AnswerCExp::Goodpasture's disease is caused by autoantibodies against glomerular basement membrane which would not cause renal masses.
Answer D	AnswerD::Transmitted in an autosomal recessive fashion
Answer D Explanation	AnswerDExp::Autosomal dominant polycystic kidney disease follows an autosomal dominant pattern of inheritance.
Answer E	AnswerE::Associated with abdominal aortic aneurysms
Answer E Explanation	[[AnswerEExp::While a relationship between ADPKD and abdominal aortic aneurysms has been proposed, a study of 139 patients failed to detect any increased risk of abdominal aortic aneurysms (Torra et al). Instead, ADPKD is associated with cerebral berry aneurysms. The incidence of these aneurysms climbs to greater than 20 percent for patients aged 60 and above.]]
Right Answer	RightAnswer::B
Explanation	[[Explanation::This patient's form of ADPKD is caused by ADPKD1 mutations. ADPKD1 is thought to encode a cellular membrane protein involved in assembly of the cilium. Educational Objective: The most common and more severe form of autosomal dominant polycystic kidney disease is caused by mutations in a cellular membrane protein involved in assembly of the cilium. References: First Aid 2014 page 87]]
Approved	Approved::Yes
Keyword	WBRKeyword::ADPKD, WBRKeyword::Autosomal dominant, WBRKeyword::Kidney, WBRKeyword::Renal
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::