Absence of urinary opioid peptides in children with Autism

Hilary Cass ^1*, Paul Gringras ², John March ³, Iain McKendrick ⁴, Anne E O'Hare ⁵, Lucy Owen ⁶ and Chris Pollin ⁷

¹ Great Ormond Street Hospital for Children, United Kingdom
² Evelina Children's Hospital, United Kingdom
³ Moredun Reseach Institute, United Kingdom
⁴ Biomathmatic and Statistic Scotland, United Kingdom
⁵ University of Edinburgh, United Kingdom
⁶ City University, United Kingdom
⁷ Moredun Research Institute, United Kingdom

^* To whom correspondence should be addressed. E-mail: cassh{at}gosh.nhs.uk.

Accepted 11 February 2008

Abstract

Aim: 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 either in the urine of children with autism, or control children.

Design: Case-control study

Setting: Cases were recruited from two tertiary referral centres specialising in autistic spectrum disorders whilst controls were recruited from and mainstream primary and secondary schools in the same geographical area.

Participants: 65 boys with autism mean age 7:4 years (5-11) and 158 control boys mean age 7:8 years (4:2-11).

Investigations: Urine samples were examined by High Pressure Liquid Chromatography (HPLC) and Matrix Assisted Laser Desorbtion Ionisation-Time of Flight Mass Spectroscopy (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 at all.

Conclusions: Given the lack of evidence for any opioid peptiduria in children with autism it can neither serve as a biomedical marker for autism, nor be employed to predict or monitor response to a casein and gluten exclusion diet.