A 6-month-old girl develops lethargy, poor feeding, hematuria, and failure to thrive. Imaging shows kidney stones. Laboratory tests show high xanthine levels. Which additional finding is expected in the most likely diagnosis?
A newborn presents with massive 5-oxoprolinuria, hemolytic anemia, and severe metabolic acidosis after a catabolic stress. Which lab abnormality is most specific to the underlying enzyme defect?
A newborn with lethargy, hypotonia, and seizures has elevated plasma glycine and an increased CSF/plasma glycine ratio. What immediate intervention is most beneficial?
A 14-month-old boy presents with coarse facial features, hepatosplenomegaly, joint contractures, and progressive developmental regression. Enzyme testing reveals markedly deficient iduronate-2-sulfatase activity, and urine glycosaminoglycans show elevated dermatan and heparan sulfate. What is the most likely diagnosis?
A 6-month-old develops acute hypoglycemia and cardiac arrest after an intercurrent viral illness. At autopsy, hepatosteatosis is found. Tandem mass spectrometry shows elevation in C8 and C10 acylcarnitines. Which treatment would be most beneficial during an acute decompensation?
A child collapses during a school sports event and is found to have myoglobinuria, elevated creatine kinase, and no evidence of infection. Which fatty acid oxidation disorder should be considered first?
A 7-year-old presents with growth failure, gout, and excessive uric acid excretion. Enzyme analysis shows low hypoxanthine-guanine phosphoribosyltransferase activity. What is the inheritance pattern of the most likely diagnosis?
A previously thriving infant rapidly deteriorates with vomiting, hepatomegaly, hypoglycemia, and cataracts after transitioning from breast milk to formula. Which laboratory result confirms hereditary fructose intolerance?
A 9-month-old presents with painful palmar hyperkeratosis, photophobia with bilateral corneal ulcers, and mild intellectual disability. Plasma tyrosine is markedly elevated. What is the underlying enzymatic deficiency?
A child with known trifunctional protein deficiency is admitted for cardiac arrhythmia, muscle weakness, and hepatomegaly following fasting. Which laboratory test is most useful to confirm the diagnosis during an acute episode?