Muscular dystrophy is a result of an abnormality of the muscle protein:

Correct Answer: B

Rationale: Muscular dystrophy is primarily caused by mutations in the gene that provides instructions for making the protein dystrophin. Dystrophin plays a crucial role in maintaining the structure of muscle fibers. Glycoprotein is a general term for proteins with sugar molecules attached, not specifically related to muscular dystrophy. Troponin is a protein involved in muscle contraction regulation, and actinomyosin is not a specific muscle protein but a complex formed during muscle contraction. Therefore, the correct answer is dystrophin.

Correct Answer: C

Rationale: The correct answer is dark urine. Rhabdomyolysis is a condition characterized by the breakdown of muscle tissue, leading to the release of myoglobin into the bloodstream. Myoglobin can cause the urine to appear dark or tea-colored, a condition known as myoglobinuria. This is a classic symptom of rhabdomyolysis. Choices A, B, and D are incorrect as they do not typically present as direct symptoms of rhabdomyolysis. Paresthesias refer to abnormal sensations like tingling or numbness, bone pain is not a primary symptom of rhabdomyolysis, and diarrhea is not a common complaint associated with this condition.

Correct Answer: B

Rationale: The correct answer is 'Herpes simplex I virus.' This disorder is known as Staphylococcal scalded skin syndrome (SSSS), where a Staphylococcus aureus organism produces an exfoliative toxin leading to skin exfoliation and large blister formation. Choices B, C, and D are incorrect. Herpes simplex viruses (I and II) cause different types of skin lesions and do not lead to exfoliation and blister formation. Necrotizing fasciitis is a severe soft tissue infection, while cellulitis is a bacterial skin infection that does not typically involve exfoliation and blister formation like in SSSS.

Correct Answer: B

Rationale: Multiple dark bands on the nails can be associated with malignant melanoma, a serious type of skin cancer. While dark bands on the nails can sometimes be a normal variant, they should not be ignored as they could also be a sign of a serious condition like melanoma. Nail fungus typically presents with different symptoms such as thickened, discolored, or brittle nails. Dark bands on the nails are not directly associated with aging.

Correct Answer: D

Rationale: The correct answer is Hemangiomas, congenital dermal melanocytosis (i.e., Mongolian spots), and macular stains. These three types of birthmarks are known to fade or regress as the child gets older. Hemangiomas are vascular birthmarks that often shrink and disappear over time. Congenital dermal melanocytosis, commonly known as Mongolian spots, usually fade by adolescence. Macular stains, also called salmon patches, tend to lighten and fade as a child grows. The other choices are incorrect because they do not typically fade or regress with age.