1 Department of Child Health, University of Sydney and Department of Biochemistry, Royal Alexandra Hospital for Children, Camperdown
A family study demonstrates the current complexity of the phenylketonuria group of diseases.
Conventional testing methods are unable to discriminate confidently between the carrier state of atypical and classical phenylketonuria. It is therefore impossible at the present time to evaluate the possibility of multiple alleles at the phenylalanine hydroxylase locus or to exclude the effects of one or more modifying genes as the cause of atypical phenylketonuria.
In the family reported, a phenylketonuric mother and father, heterozygous for the phenylketonuric gene, have produced three children, two with atypical phenylketonuria and the other a heterozygote. All the children were microcephahic and retarded, reflecting the intra-uterine damage caused by the mother's phenylketonuria.
Submitted on January 12, 1970