Maternal Phenylketonuria (PKU)
If the Phe-restricted
diet is discontinued during pregnancy, asymptomatic woman
with a PKU genotype who have been successfully treated early in
life may introduce high levels of Phe into the fetal circulation. This
results in a condition known as maternal PKU. Even
though the developing fetus does not have a PKU genotype,
exposure to high levels of Phe in utero
during early development (before the woman knows she is
pregnant) can result in a PKU phenotype in the
newborn. For this and other reasons, persons with a PKU
genotype are often advised to remain on the low Phe
diet throughout their lives.
Homework: Why is this not a concern when a
mother with a non-PKU genotype
is carrying a fetus with the PKU genotype?