Objective: It has been claimed for a number of years that the urine of children with autism contains exogenously derived opioid peptides. This finding is said to reflect a disturbance in the integrity of the gut epithelium, act as a diagnostic marker for autism and predict treatment response to a diet excluding gluten and casein. The aim of the present study was to determine whether exogenous or endogenous peptides were present in the urine of children with autism or of control children.
Design: Case-control study
Setting: Cases were recruited from two tertiary referral centres specialising in autistic spectrum disorders, while controls were recruited from mainstream primary and secondary schools in the same geographical area.
Participants: 65 boys with autism, mean age 7.4 years (range 5–11) and 158 control boys, mean age 7.8 years (range 4.2–11).
Investigations: Urine samples were examined by high pressure liquid chromatography (HPLC) and matrix assisted laser desorbtion ionisation-time of flight mass spectrometry (MALDI-TOF MS) for the presence of a number of putative opioid peptides.
Outcomes: There were no significant differences between the HPLC urinary profiles of the children affected by autism and the typically developing controls. In those cases where HPLC showed peaks in the locations at which opioid peptides might be expected to be found, MALDI-TOF established that these peaks did not, in fact, represent opioid peptides.
Conclusions: Given the lack of evidence for any opioid peptiduria in children with autism, opioid peptides can neither serve as a biomedical marker for autism nor be employed to predict or monitor response to a casein- and gluten-free diet.
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Funding: JM has previously acted as an expert witness for the litigants in the MMR litigation case conducted by Alexander Harris against three MMR vaccine manufacturers, which involved urinary analysis of both litigants and non-litigant controls using MALDI-TOF mass spectrometry. He has an autistic child who was not part of this legal case.
Competing interests: This research was funded by the R&D Fund, RHSC, Edinburgh and the Chief Scientist Office, Edinburgh. Dr Lucy Owen’s post was funded by Ortho-Clinical Diagnostics, a UK based diagnostics arm of Johnson and Johnson.
Ethics approval: Obtained from the local ethics committee and the National Autistic Society research ethics committee.
Patient consent: Obtained.