WBR0318

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Neurology
Prompt	[[Prompt::A 6-month-old male is brought by his mother to the physician's office for failure to thrive. Following appropriate work-up, that patient is diagnosed with a disease that is characterized by failure of mannose-6-phosphate addition to lysosomes. Which of the following clinical features are most likely to be present in this patient?]]
Answer A	AnswerA::Clouded corneas and restricted joint movement
Answer A Explanation	AnswerAExp::Patients with I-cell disease, caused by failure of mannose-6-phosphate to be added to lysosomal proteins, present with clouded corneas and restricted joint movement.
Answer B	AnswerB::Partial albinism and peripheral neuropathy
Answer B Explanation	AnswerBExp::Chediak-Higashi syndrome is a disease characterized by 3Ps: Peripheral neuropathy, Peripheral neuropathy, and Pyogenic infections. It is due to lysosomal trafficking regular gene mutation.
Answer C	AnswerC::Situs inversus and bronchiectasis
Answer C Explanation	AnswerCExp::Kartagener's syndrome or primary ciliary dyskinesia is characterized by infertility, bronchiectasis, sinusitis and is associated with situs inversus. It is due to dynein arm defect.
Answer D	AnswerD::Thymic aplasia and recurrent infections
Answer D Explanation	AnswerDExp::Severe combined immunodeficiency is characterized by thymic aplasia and recurrent infections (bacterial, viral, fungal, and protozoal). It is most commonly due to defective interleukin-2 receptor or adenosine deaminase deficiency.
Answer E	AnswerE::Hepatomegaly and aseptic necrosis of the femur
Answer E Explanation	AnswerEExp::Gaucher's disease is a lysosomal storage disease characterized by hepatomegaly and aseptic necrosis of the femur. On pathology, Gaucher's cells ("crumpled tissue paper" macrophages) are present.
Right Answer	RightAnswer::A
Explanation	[[Explanation::The patient is most likely presenting with inclusion cell disease or I-cell disease (mucolipidosis type II), a lysosomal storage disease characterized by failure of mannose-6-phosphate to be added to lysosomes due to a defect of phosphotransferase, which is normally found on the Golgi apparatus. Consequently, enzymes will be secreted extracellularly rather than being targeted by the lysosome. Typical clinical features of I-cell disease are coarse facial features, restricted joint movement, and clouded corneas in very young children. The disease is usually deadly in childhood. Educational Objective: Clinical features of I-cell disease are coarse facial features, clouded corneas, and restricted joint movement. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::restricted, WBRKeyword::joint, WBRKeyword::movement, WBRKeyword::I-cell, WBRKeyword::i, WBRKeyword::cell, WBRKeyword::disease, WBRKeyword::inclusion, WBRKeyword::cell, WBRKeyword::disease, WBRKeyword::inclusion, WBRKeyword::mannose-6-phophase, WBRKeyword::mannose, WBRKeyword::phosphate, WBRKeyword::6, WBRKeyword::lysosome, WBRKeyword::lysosomes, WBRKeyword::lysosomal, WBRKeyword::protein, WBRKeyword::proteins, WBRKeyword::mucolipidosis, WBRKeyword::coarse, WBRKeyword::facial, WBRKeyword::feature, WBRKeyword::features
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