James Dobson’s research while affiliated with University of British Columbia and other places

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.

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.