Why is this disorder almost never seen in girls?
Duchenne muscular dystrophy (DMD) is caused by a sex-linked recessive. Its victims are invariably boys, who usually die before the age of 20.
A. Sex-linked traits are never seen in girls B. The allele is carried on the Y chromosome. C. Nondisjunction occurs in males but not in females. D. Males carrying the alleles don t live long enough to be fathers. E. A sex-linked allele cannot be passed from mother to daughter.