WBR0219

Author	[[PageAuthor::William J Gibson (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Genetics, MainCategory::Pathophysiology
Sub Category	SubCategory::Head and Neck, SubCategory::Renal
Prompt	[[Prompt::A 7-year-old boy is brought to his primary care physician for progressive bilateral deafness. Family history is significant for multiple family members who suffered from a similar condition at childhood. Physical examination is remarkable for subcapsular posterior lens opacities and sensorineural deafness. The physician suspects the patient's condition is caused by a genetic disease. Genetic testing results demonstrate a frameshift mutation in the COL4A5 gene. Further work-up will most likely be remarkable for abnormalities in which of the following tests?]]
Answer A	AnswerA::Serum creatinine
Answer A Explanation	[[AnswerAExp::Alport's syndrome is a familial cause of deafness, ocular disturbances, and nephritis. Although patients eventually develop end stage renal disease (ESRD), serum creatinine is often normal early in the course of the disease, and the diagnosis may be missed.]]
Answer B	AnswerB::Electrocardiogram
Answer B Explanation	AnswerBExp::Alport's syndrome is not primarily associated with cardiac disease or changes on electrocardiogram (ECG).
Answer C	AnswerC::Urinalysis
Answer C Explanation	[[AnswerCExp::Alport's syndrome is a familial cause of deafness, ocular disturbances, and nephritis. Microscopic hematuria is the most common presenting sign of patients with Alport's syndrome. Hematuria is usually present before patients experience symptoms of renal failure (eg. hypertension) and before an elevation in serum creatinine is observed.]]
Answer D	AnswerD::Alanine aminotransferase
Answer D Explanation	AnswerDExp::Alport syndrome is not primarily associated with abnormal values of alanine aminotransferase (ALT) or liver abnormalities.
Answer E	AnswerE::Platelet counts
Answer E Explanation	AnswerEExp::Alport's syndrome is not primarily associated with quantitative platelet disturbances.
Right Answer	RightAnswer::C
Explanation	[[Explanation::Alport’s syndrome (hereditary nephritis) is a familial nephropathy characterized by renal impairment, auditory manifestations, and ocular defects. It has an X-linked form, which is characterized by the mutation of COL4A5 gene on the long arm of the X-chromosome, and another much less common autosomal recessive form characterized by the homogeneous mutation of COL4A3 or COL4A4 on chromosome 2. The mutation leads to abnormal alpha chain of type IV collagen, which is normally responsible for the structure and function of basement membranes in the body. Alport’s syndrome most commonly presents in childhood with persistent hematuria. Prognosis of Alport’s syndrome is generally poor with inevitable progression to end-stage renal disease (ESRD) at varying rates. Alport's syndrome should always be considered among children with any of auditory, ocular, and/or urinary findings. Nonetheless, it should be distinguished from other diseases that may present with similar symptoms (table below). Management is by multidisciplinary approach, involving established and promising pharmacologic therapy along with renal replacement methods, such as dialysis and renal transplantation. Educational Objective: Alport's syndrome is a familial cause of deafness, ocular disturbances, and nephritis. References: McCarthy PA, Maino DM. Clin Eye Vis Care. 2000; 12(3-4):139-50. Savige J, Gregory M, Gross O, et al. Expert guidelines for the management of Alport syndrome and thin basement membrane nephropathy. J Am Soc Nephrol. 2013; 24(3):364-75. First Aid 2014 page 538]]
Approved	Approved::Yes
Keyword	WBRKeyword::Alport's syndrome, WBRKeyword::Alport, WBRKeyword::Nephritis, WBRKeyword::Deafness, WBRKeyword::Hearing loss, WBRKeyword::Hematuria, WBRKeyword::Creatinine, WBRKeyword::Work-up, WBRKeyword::COL4A5, WBRKeyword::Hereditary nephritis
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