WBR0645

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Biochemistry
Sub Category	SubCategory::Dermatology, SubCategory::General Principles
Prompt	[[Prompt::Which of the following steps in collagen synthesis is likely to be defective in this patient? ]]
Answer A	AnswerA::A
Answer A Explanation	AnswerAExp::This step refers to the hydroxylation of proline and lysine residues mediated by Vitamin C. Scurvy would lead to a defect in this phase of collagen synthesis. It is not affected in Ehlers-Danlos syndrome.
Answer B	AnswerB::B
Answer B Explanation	AnswerBExp::This step refers to glycosylation of specific residues in the collagen chain. It is not affected in Ehlers-Danlos syndrome.
Answer C	AnswerC::C
Answer C Explanation	AnswerCExp::This step refers to collagen triple helix (procollagen) formation. It is defective in osteogenesis imperfecta. It is not affected in Ehlers-Danlos syndrome.
Answer D	AnswerD::D
Answer D Explanation	AnswerDExp::This step refers to the cleavage of the terminal regions of procollagen. It is not affected in Ehlers-Danlos syndrome.
Answer E	AnswerE::E
Answer E Explanation	AnswerEExp::This refers to collagen cross-linking via lysyl-oxidase (requires copper). This step is the defective step in Ehlers-Danlos disease.
Right Answer	RightAnswer::E
Explanation	[[Explanation::Ehlers-Danlos Learning objective: Reference: Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Ehlers-Danlos Syndrome, WBRKeyword::Collagen sythesis, WBRKeyword::Lysyl oxidase
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::