THE NORTH-AMERICAN MATERNAL PHENYLKETONURIA COLLABORATIVE STUDY, DEVELOPMENTAL ASSESSMENT OF THE OFFSPRING - PRELIMINARY-REPORT

Preliminary results of 2-year Bayley and 4-year McCarthy test scores a re presented. To date numbers are too small to statistically correlate : - offspring from pregnancies in which diet was started prior to conc eption, offspring from pregnancies with phenylalanine (Phe) levels of 120-360 mu mol/l versus 360-600 mu mol/l, influence of home environmen t, influence of maternal nutrition, language development, behaviour/hy peractivity, Revised Wechsler Intelligence Score, school performance a nd learning disabilities. Two-year Bayley scores (mental and motor) re vealed a median developmental quotient of 113 in 58 off-spring from co ntrol pregnancies, 104 in 19 offspring from untreated ''non-phenylketo nuria (PKU) mild hyperphenylalaninaemia'' (natural Phe levels < 600 mu mol/l) pregnancies, 104 in 32 offspring from pregnancies whose Phe le vels decreased on treatment to < 600 mu mol/l by 10 weeks gestation an d remained in that range for the remainder of the pregnancy, 98 in off spring from 32 pregnancies where permanent control was not achieved un til 10-20 weeks and 72 in offspring from 51 pregnancies where control was not attained until after 20 weeks gestation. IQ scores determined by the McCarthy test at age 4-5 years revealed a mean of 112 in 43 off spring of control mothers, 99 in 12 offspring of ''non PKU mild hyperp henylalaninaemia'' women, 93 in 14 offspring whose mother's Phe levels were continuously under 600 mu mol/l by 10 weeks gestation, 88 in 24 offspring from pregnancies in metabolic control by 10-20 weeks and 73 in 28 offspring of pregnancies not in metabolic control until after 20 weeks gestation. These preliminary results suggest that early and ade quate dietary treatment during pregnancy in maternal PKU may provide s ome protection to the fetus for later intellectual development but muc h more data is required before definitive statements about cognition c an be made.