question: A 4-year-old boy of a first-degree consanguineous couple was noted by the parents to have darkening of the urine to an almost black color when it was left standing. He has a normal sibling, and there are no other medical problems. Growth and development to date are normal. Which of the following is most likely to be elevated in this patient?
opa: Methylmalonate
opb: Homogentisate
opc: Phenylpyruvate
opd: a-Ketoisovalerate