Some observations on the blood levels of phenylalanine in dilute mice and a comparison between human phenylketonuria and the disease of mice homozygous for the dilute lethal gene

Abstract

The plasma phenylalanine levels of adult and juvenile (18–22 days old) dilute mice were measured. No difference could be found between the levels of the dilute lethal mice and their normal litter‐mates. However, in two dying dilute lethal mice the levels were markedly raised. The adult mice had a significantly lower concentration than the juveniles. Dilute lethal mice subjected to a phenylalanine load (300 mg/kg) had normal blood phenylalanine levels when tested two hours later. The apparent similarity of many clinical aspects of human phenylketonuria and the disease of the dilute lethal mice is discussed, but it is shown that when studied in detail the similarity is usually only superficial. It would appear that the dilute lethal mice cannot be regarded as a model for “classical” phenylketonuria in man or its variants with raised blood phenylalanine levels.