Galactosemia is a condition that affects how the body digests the sugar galactose. The most common form of galactosemia, type I, is the most severe, and it results from mutations within the GALT gene, which encodes for an enzyme that processes galactose. Galactosemia is inherited in an autosomal recessive pattern.

Imagine that your friend Mary has normal metabolism, but that her brother John has galactosemia. Mary and John's parents, Patricia and Les, are unaffected, although their maternal grandmother, Jean, also had the condition. Jean Patricia Gg Gg Les 2 John Mary

If Patricia and Les have another child, what is the probability that they will have a daughter that is affected with galactosemia?