A family is referred to a genetic specialist because of mild mental retardation in several of the school-age children. Laboratory evaluation demonstrates a specific chromosomal breakage site in metaphase studies of lymphocytes cultured with methotrexate. Which of the following chromosomes is most likely to be specifically affected?
A. X
B. Y
C. 13
D. 16
E. 21
A. X
B. Y
C. 13
D. 16
E. 21