Final intelligence in late treated patients with phenylketonuria.

UNLABELLED: Despite neonatal screening programmes, there is still a number of patients with phenylketonuria who are not diagnosed and start treatment late. The question in this study was to evaluate which factors will contribute, other than the quality and duration of dietary treatment, to final outcome in late treated patients with phenylketonuria. We retrospectively analysed the data of 40 patients with phenylketonuria, of whom 2 patients at 35 and 24 years of age had a normal IQ despite never being treated. In 38 patients starting dietary treatment between 0.7 and 7 years of age, mean IQ/DQ at diagnosis was 52.7 (SD = 16) (mean age 2.5 years), final IQ (mean age 33.5 years) was 79.0 (SD = 16), the difference was highly significant (P < 0.0001). Important factors for the final intelligence in adult late treated patients with phenylketonuria were onset (r = -0.46, P < 0.009) and DQ/IQ (r = 0.51, P < 0.002) when dietary treatment was started. Thus, in late treated patients with phenylketonuria, in addition to the quality and duration of treatment, the outcome is mainly influenced by the age of starting treatment and also by the intellectual status of the patient. In one of the two patients with normal intelligence, nuclear magnetic resonance spectroscopy showed that brain phenylalanine was undetectable even though blood phenylalanine was 30 mg/dl. A second metabolic disorder may protect these patients from severe brain damage. CONCLUSION: These data indicate that brain damage in untreated or late treated patients with phenylketonuria is influenced by various genetic factors.

Outcome at age 4 years in offspring of women with maternal phenylketonuria: the Maternal PKU Collaborative Study.

CONTEXT: Untreated maternal phenylketonuria (PKU) increases risk for developmental problems in offspring. The extent to which this risk is reduced by maternal dietary therapy at various stages of pregnancy is not known. OBJECTIVE: To determine whether dietary treatment during pregnancy of women with PKU affects developmental outcomes of offspring. DESIGN: The Maternal PKU Collaborative Study, an ongoing, longitudinal prospective study begun in 1984. SETTING: A total of 78 metabolic clinics and obstetrical offices in the United States, Canada, and Germany. PARTICIPANTS: A total of 253 children of women with PKU (n = 149), with untreated mild hyperphenylalaninemia (n = 33), or without known metabolic problems (comparison group; n = 71) were followed up to age 4 years. INTERVENTION: Women with PKU were offered a low-phenylalanine diet prior to or during pregnancy with the aim of maintaining metabolic control (plasma phenylalanine < or =10 mg/dL [< or =605 micromol/L]). Women with mild hyperphenylalaninemia, who had plasma phenylalanine levels of no more than 10 mg/dL (605 micromol/L) on a normal diet, were not treated. MAIN OUTCOME MEASURES: Children's scores on cognitive and behavioral assessments (McCarthy Scales of Children's Abilities, Test of Language Development, Achenbach Child Behavior Checklist, Vineland Adaptive Behavior Scales, and Home Observation for Measurement of the Environment), compared by maternal metabolic status at 0 to 10 weeks', 10 to 20 weeks', and after 20 weeks' gestation. RESULTS: Scores on the McCarthy General Cognitive Index decreased as weeks to metabolic control increased (r = -0.58; P<.001). Offspring of women who had metabolic control prior to pregnancy had a mean (SD) score of 99 (13). Forty-seven percent of offspring whose mothers did not have metabolic control by 20 weeks' gestation had a General Cognitive Index score 2 SDs below the norm. Overall, 30% of children born to mothers with PKU had social and behavioral problems. CONCLUSIONS: Our data suggest that delayed development in offspring of women with PKU is associated with lack of maternal metabolic control prior to or early in pregnancy. Treatment at any time during pregnancy may reduce the severity of delay.

German Maternal Phenylketonuria Study.

The German maternal phenylketonuria (MPKU) Study began in 1989 and since 1992 works together with the American-Canadian MPKU Study. Main goals of the study are: (1) to find women with phenylketonuria (PKU) and mild untreated hyperphenylalaninaemia (HPA); (2) to inform them about the risks of an untreated pregnancy with PKU and HPA; (3) to evaluate the efficacy of the phenylalanine (Phe) restricted dietary treatment prior to and during pregnancy by following the physical and cognitive development of offspring from treated pregnancies. An interim report of the study is presented. Until now, 43 pregnancies have been followed. They resulted in 34 live births, 24 from women with PKU and 10 form women with HPA. There are significant negative correlations between the gestational age in which the dietary control (blood Phe level < 360 mumol/l) was reached and pregnancy outcome as measured by growth parameters and early cognitive and motor developmental quotients at the age of 2 years. For minimizing risks of MPKU, preconceptional dietary control is strongly recommended. Tracking and timely information of young women about risks of MPKU is of outmost importance.