Absence of urinary opioid peptides in children with autism

Abstract

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.Autism is a severe lifelong developmental disorder, defined on the basis of behavioural characteristics which result from impairments in social communication and reciprocal social interaction, repetitive and restrictive behaviours, and imaginary thought.

Complementary and Alternative Medicine in Autism: An Evidence-Based Approach to Negotiating Safe and Efficacious Interventions with Families

“…Recently, rigorously designed studies have used more accurate methods (mass spectrometry) to investigate the validity of peptiduria and have refuted the initial findings. 77,78 From a study reported in 2008, Cass et al 77 concluded that, in the absence of evidence for opioid peptiduria in children with ASD, urinary peptides cannot serve as a biomedical marker for ASD, nor can they be used to monitor response to the GFCF diet. These authors also stressed that children with ASD should not be subjected to urinary testing for peptiduria, and their parents should not be subjected to the expense of testing that has been clearly established to have no role in the diagnosis or management of ASD.…”

“…These authors also stressed that children with ASD should not be subjected to urinary testing for peptiduria, and their parents should not be subjected to the expense of testing that has been clearly established to have no role in the diagnosis or management of ASD. 77 The GFCF diet can be difficult for families to implement, with common challenges including increased preparation time, increased food-related expenses, and children refusing to eat the dietary selections. Families must consider the implications of further dietary restriction in a child who may already have a limited food repertoire.…”

Formation and Degradation of Beta-casomorphins in Dairy Processing

“…The possibility to extend the application of HPLC-MS to determine BCMs content in biological fluids such as urine does exist (Cass et al, 2008) as this technique has been proven rather flexible, accommodating the analysis of a wide range of matrices.…”

“…For example, RP-HPLC-UV (Muehlenkamp and Warthesen, 1996) and ionexchange chromatography (Jarmolowska et al, 1999) have been used for the separation and quantification of BCM7 present in cheese while HPLC-UV has been also used for determining BCM7 content in human milk (Jarmo»owska et al, 2007). A limitation of RP-HPLC-UV is that peptides with similar physico-chemical and spectrophotometric absorption properties can co-elute with BCMs, increasing the absorption values (Muehlenkamp and Warthesen, 1996;SienkiewiczSz»apka et al, 2009), resulting in an overestimation of the BCM7 content (Cass et al, 2008). In addition, methods employing UV-Vis adsorption may lack the sensitivity required to quantify low levels of BCM7 found in some dairy products.…”

“…For example, using HPLC TOF-MS, Toelstede et al (2008) found BCM9 and BCM10 in the water-soluble extract of a matured Gouda cheese. The possibility of interfacing a matrix-assisted laser desorption ion source (MALDI) to a TOF-MS allowed Cass et al (2008) to analyze opioid-derived exogenous or endogenous peptides in urines of children with autism, and found that peaks previously analyzed by HPLC-UV were erroneously identified as opioid peptides. Hence the need of high resolution for identification and confirmation work.…”