Question

Duchenne muscular dystrophy (DMD) is an X-linked recessive condition that causes rapid muscle degeneration. DMD occurs in approximately 1 in every 3500 males, but it rarely affects females. Which statement most accurately explains why DMD affects males more often than females?

Answer 1

Answer:

Option D

Explanation:

Options for the question

A) The Y chromosome is slower to mature than the X chromosome.

B) Replication of the X chromosome occurs more often in males.

C) Male hormones cause the expression of X-linked traits.

D) Males only have one copy of the X chromosome

Given-

Duchenne muscular dystrophy (DMD) is an X-linked recessive condition which means it will occur in male even if they have one diseased X gene. While females will have this disease only when they have two diseased X gene

Hence, in most of the cases women with only one diseased X chromosome act as carrier and show normal traits.

Let us assume X is normal gene and X' is the diseased gene then

Genotype of normal father will be - XY

Genotype of carrier mother will be - XX'

Now if these two mates, following offspring will be produced

XY * XX'

XX, XX', XY, X'Y

So the male with X'Y will have DMD

Hence, option D is correct