Question

Fragile X syndrome (F or f) is a dominant X-linked disease that often causes autism or autism like symptoms. Poindexter has Fragile X and marries Allie who does not. Using a Punnet Square give the likelihood of having children with Fragile X.

Poindexter’s genotype _________ phenotype ____________
Allie’s genotype _________ phenotype ____________
Percent of sons with Fragile X _________
Percent of daughters with Fragile X _______

Answer 1

Poindexter’s genotype - X_FY, phenotype - autism

Allie’s genotype - X_fX_f, phenotype - healthy

Percent of sons with Fragile X - 0%

Percent of daughters with Fragile X - 100%

       X_F       Y

X_f   X_FX_f   X_fY

X_f  X_FX_f   X_fY