Maternal phenylketonuria: a continuing problem

Objectives: To estimate the number of women of childbearing age in New South Wales whose children are at risk of the maternal phenylketonuria (PKU) syndrome (intellectual disability, microcephaly, congenital malformations). Setting: New South Wales, 1996. Design: Comparison of number of women with PKU aged 15-44 years on the NSW PKU database (observed number) with expected number derived from population data. Main outcome measures: Observed and expected numbers of women with PKU (defined as blood phenylalanine levels greater than or equal to 400 mu mol/L, and phenylalanine-restricted diet recommended) by age; number with no clinical contact with the PKU service in previous year; outcomes of pregnancies in women with PKU (January 1994 to July 1996). Results: 110 women aged 15-44 years with PKU were listed on the database. The expected number was 145 (95% confidence interval, 122-171). The difference was greatest in the 30-44 years age group (born before comprehensive newborn screening), with only 55% of the expected number listed. Sixteen women who had been diagnosed with PKU at birth were not having regular follow-up, while 18 women had been diagnosed only after investigation of abnormalities in their children. Of 28 pregnancies managed by the NSW PKU service, 19 were considered unaffected by the maternal PKU syndrome and five affected (another three did not reach term; one outcome was unknown). Of 46 unmanaged pregnancies, all were affected. Conclusion: There is an urgent need for better follow-up of women with PKU and for education of health professionals about the MPKU syndrome, its recognition, the risks of untreated pregnancy and the benefits of dietary treatment.