Phenylketonuria

Parents of a newly diagnosed infant with PKU should be provided with genetic counselling regarding the autosomal-recessive nature of the condition, with a 25% risk of recurrence in subsequent pregnancies. If 2 phenylalanine hydroxylase mutations are detected, carrier testing is possible for other family members and pre-implantation or antenatal diagnosis is an option in future pregnancies. Once they have adjusted to the diagnosis and become comfortable with the care of a child with PKU, few couples actually choose to use antenatal diagnosis. Blood phe testing should be expedited on all siblings born to patients with PKU so that treatment can be initiated at the earliest possible time. Adolescent and adult women with PKU should be educated regarding their risks of having a child with maternal PKU syndrome. Contraceptive counselling should be provided so that unplanned pregnancies can be prevented.