A couple whose child had a positive newborn screen for galactosemia is seen for genetic counseling. Followup testing showed slightly reduced GALT enzyme activity, gal1p and galactitol levels within normal limits, and one copy of the Q188R mutation in the GALT gene. Which of the following is MOST important to discuss with the parents?

A. Explain that screening tests are not diagnostic.
B. Recommend the enzyme studies be repeated. C. Discuss the management of galactosemia.
D. Describe the purpose of newborn screening.