Symptomatic Phenylketonuria


Harry Jude

Case Report

The presenting symptom in this 29-year-old gentleman with phenylketonuria was intermittent anxiety and right sided tinnitus which could be adjusted and induced by rubbing the right side of his face anteriorly to the ear.  

An MRI was done which showed diffusion related changes and periventricular high signal changes that are consistent with PKU. There were some atypical findings of T2 signal change in the white matter of his herniated ectopic cerebellar tonsil although this is not of significance. 

These findings are consistent with the patients self-reported poor compliance with a PKU friendly diet and an increase in his dietary phenylalanine from age 18. The only other significant history of note is that this gentleman is a heterozygote for two common HFE gene mutations that could predispose him to haemochromatosis. 

It is proposed that increased phenylalanine levels can impact brain growth, myelination and neurotransmitter synthesis. Other presentations of PKU include seizures, behavioural abnormalities, microcephaly and skin disease.