James C. Dobson

Cognitive development and dietary therapy in phenylketonuric children.

Abstract Phenylketonuric children (now four years of age or older) were given intelligence and language tests to ascertain their present levels of cognitive functioning. These intellectual abilities were then evaluated in relation to the childrens ages at the time diets low in phenylalanine were begun. The influence of distorting nontreatment factors, such as family level of intelligence and sociologic variation, was ascertained by computation of a multiple-regression equation analysis. Examination of the data revealed a consistent inverse relation between present intellectual ability and age of dietary inception. The children treated within one month after birth scored an average of 33 IQ points higher than those for whom treatment was initiated within their fourth and sixth years of life.

ALTERED SEX RATIO AMONG PHENYLKETONURIC INFANTS ASCERTAINED BY SCREENING THE NEWBORN

Abstract Of 90 infants included in a collaborative study of phenylketonuria (P.K.U.) 60 were males and 30 were females. The method of ascertainment seems to have played a part in this altered sex ratio since the high proportion of males was found only in series ascertained by screening alone. In this series there were 7 cases (all female) in which the rise in blood-phenylalanine was delayed. Such cases would be missed in routine screening in the first forty-eight hours of life. Another explanation could be that one published series of P.K.U. (near-normal I.Q.) contained an excess of females, and such cases might escape detection. It is suggested that the Guthrie test be repeated later than forty-eight hours after birth and that plasma-phenylalanine levels be measured serially in at-risk infants.

Conference on sex ratio in phenylketonuria

Summary A conference was held to discuss the significance of the disproportionate sex ratio (2:1) observed in the Collaborative Study of Children Treated for Phenylketonuria. No definite conclusions were arrived at concerning the cause of this observation, but it was felt that the present screening programs are sound and are not missing significant numbers of children with phenylketonuria. If the observation of an altered sex ratio has not occurred by chance in the PKU Collaborative Study, this could be the result of the criteria for inclusion in the Collaborative Study or of a slight variation in how the sexes metabolize phenylalanine.