A 25yearold woman comes for genetic counseling at 12 weeks gestation because her sister recently had a baby girl with a "metabolic condition." She was told that her niece has recurrent vomiting, seizures, and smells like "sweaty feet." The niece was born overseas, medical records cannot be obtained, and the woman is estranged from her sister. The genetic counselor should look for laboratories that offer carrier testing for which of the following conditions?
A. maple syrup urine disease
B. propionic acidemia
C. methylmalonic acidemia
D. isovaleric acidemia