MATERNAL NON-PHENYLKETONURIC MILD HYPERPHENYLALANINEMIA

Unlike maternal phenylketonuria (PKU) which produces severe birth defe cts when untreated during pregancy, maternal non-PKU mild hyperphenyla laninemia (MHP) has a less severe impact but whether it is benign or m ay have long-term consequences for offspring has been unclear. From an international survey of maternal MHP we obtained information about 86 mothers (blood phenylalanine (Phe) 150-720 mu mol/l). their 219 untre ated pregnancies and 173 offspring, Spontaneous fetal loss and congeni tal anomalies were no more frequent than normally expected. Median Z-s cores for birth length and birth head circumference and offspring IQ ( 100), however, were significantly lower for maternal Phe > 400 mu mol/ l than for maternal Phe < 400 mu mol/l, in which the median offspring IQ was 108. Data on maternal MHP from the prospective Maternal PKU Col laborative Study (MPKUCS) are as yet incomplete but seem to be conform ing to the general pattern of the international survey. We conclude th at maternal blood Phe levels above 400 mu mol/l in maternal MHP are as sociated with lower birth measurements and slightly lower offspring IQ . It would seem that dietary intervention to lower the maternal Phe le vels to below 400 mu mol/l might be indicated in maternal MHP pregnanc ies with the higher blood Phe levels.