Fragile X syndrome, caused by a change in the FMR1 gene, is the
most common form of intellectual disability. In patients with this
syndrome, a small part of the gene is repeated several times in one
area of the chromosome. This defect in the gene makes the body
unable to produce adequate amounts of a protein needed for normal
brain functioning. In males, this syndrome causes a moderate
intellectual disability, and in females, a mild intellectual
disability.
A family that exhibits Fragile X syndrome is shown in the
pedigree. In the pedigree, squares represent males and circles
represent females. Shaded symbols represent a person with the
disorder.
Which of the following correctly predicts the outcome if
offspring 11 mated with a homozygous normal female, based on the
inheritance pattern shown in the pedigree?
The male offspring would exhibit Fragile X syndrome because
Fragile X is an X-linked recessive trait.
The female offspring would exhibit Fragile X syndrome because
Fragile X is a recessive autosomal trait.
None of their offspring would exhibit Fragile X syndrome because
Fragile X is an X-linked dominant trait.
Both the male and female offspring exhibit Fragile X syndrome
because Fragile X is a dominant autosomal trait