An investigator is studying a hereditary defect in the mitochondrial enzyme succinyl-CoA synthetase. In addition to succinate, the reaction catalyzed by this enzyme produces a molecule that is utilized as an energy source for protein translation. This molecule is also required for which of the following conversion reactions?
AOxaloacetate to phosphoenolpyruvate
BPyruvate to acetyl-CoA
CAcetaldehyde to acetate
DGlucose-6-phosphate to 6-phosphogluconolactone
EFructose-6-phosphate to fructose-1,6-bisphosphate
A 2-day-old male infant is brought to the emergency department by ambulance after his parents noticed that he was convulsing and unresponsive. He was born at home and appeared well initially; however, within 24 hours he became increasingly irritable and lethargic. Furthermore, he stopped feeding and began to experience worsening tachypnea. This continued for about 6 hours, at which point his parents noticed the convulsions and called for an ambulance. Laboratories are obtained with the following results: Orotic acid: 9.2 mmol/mol creatinine (normal: 1.4-5.3 mmol/mol creatinine) Ammonia: 135 µmol/L (normal: < 50 µmol/L) Citrulline: 2 µmol/L (normal: 10-45 µmol/L) Which of the following treatments would most likely be beneficial to this patient?
AGalactose avoidance
BAspartame avoidance
CBenzoate administration
DUridine administration
EFructose avoidance
A 2-week-old boy presents to the emergency department because of unusual irritability and lethargy. The patient is admitted to the pediatric intensive care unit and minutes later develops metabolic encephalopathy. This progressed to a coma, followed by death before any laboratory tests are completed. The infant was born at home via vaginal delivery at 39 weeks' of gestation. His mother says that the symptoms started since the infant was 4-days-old, but since he only seemed ‘tired’, she decided not to seek medical attention. Further testing during autopsy shows hyperammonemia, low citrulline, and increased orotic acid. Which of the following enzymes is most likely deficient in this patient?
ABranched-chain alpha-ketoacid dehydrogenase
BPropionyl-CoA carboxylase
CHomogentisic acid dioxygenase
DOrnithine transcarbamylase
ECystathionine beta-synthase
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