Will anything change now that cutting-edge techniques have provided support for the conclusions of Andrew Wakefield’s controversial 1998 Lancet case series?
Case series confirmed
Science doesn’t exist in a vacuum: if a piece of research into an active area of scientific enquiry is valid, sooner or later it will be repeated or otherwise confirmed by other researchers. To listen to any of Andrew Wakefield’s many detractors, one would think that no scientific evidence has emerged since 1998 in support of his supposedly fraudulent case series, retracted by theLancet in 2010. But that’s simply not true, as has been pointed out before, not least by Wakefield himself in his second book, Waging War on the Autistic Child . This week, open-access journal PLOS One has published data that powerfully confirm Wakefield et al’s original results.
From macro to micro
The 1998 Lancet paper was a case series reporting observations of a group of children who presented with similar symptoms. The 2013 research published in PLOS One, by contrast, harnessed sophisticated laboratory techniques, but toward a similar goal: to focus in on the molecular changes occurring in the intestinal cells of children with ASD and inflammation of the small (ileitis) or large (colitis) bowel, or both. Importantly, the new study not only compared the intestinal molecular profiles of ASD children with those of healthy, control children; it also compared them with changes occurring in the bowels of children with the inflammatory bowel conditions Crohn’s disease (CD) and ulcerative colitis (UC). If the changes observed in ASD children were distinct from those of the CD and UC children, it would validate Wakefield’s 1998 finding of a novel syndrome in ASD children.
How did they do it?
Six children with autism and a further 19 with ASD were included in the study, all of whom had confirmed diagnoses of ileitis, colitis or both. Cells were taken from the small and large bowel of these children, and the samples were subjected to microarray analysis – a technique that assesses the gene expression profiles of the samples. The result is a small glass slide or silicon chip containing information on all of the myriad genes that are turned on or off in the sample: a true snapshot of the molecular processes occurring in the cells. An identical procedure was used on samples from eight non-autistic and non-ASD children with CD, five non-autistic/non-ASD children with UC and 15 healthy controls.
Figure 1. Scatterplot representing 53 individual microarray datasets from terminal ileum tissues. Each circle represents the cumulative gene expression profile for an individual sample. Samples with similar profiles cluster together in the three-dimensional space, as shown by the black ellipses. Adapted from Walker SJ et al. PLOS One 2013;8(3):e58058. doi:10.1371/journal.pone.0058058
Figure 1 is a graphical representation of the gene expression profiles of the samples analysed by the PLOS One researchers. The circles show that the different populations – ASD, CD/UC and healthy controls – formed three defined clusters, with an area of overlap between the ASD population and the CD/UC population.
Figure 2. Gene expression profiles taken from children with inflammatory bowel disease and autism spectrum disorder (ASD-GI), compared with those taken from children with Crohn’s disease (CD), ulcerative colitis (UC) and healthy controls (the ‘C’ in ‘CD v C’ etc.). Values in the circles are the numbers of genes uniquely expressed in each sample, while the numbers in the overlapped sections represent genes that were commonly expressed in all of the samples forming the overlap. For example, in diagram C, 1231 genes were expressed only in the terminal ileum (TI) of ASD-GI children, while 178 genes were expressed in both the TI and colon of ASD-GI children. From Walker SJ et al. PLOS One 2013;8(3):e58058. doi:10.1371/journal.pone.0058058
Figure 2 takes this a step further. The Venn diagrams show the degree to which the genes expressed in the samples taken from ASD, CD/UC and healthy children differ and overlap between the three populations. Although there was some overlap, it’s clear that distinct molecular processes occurred in each population.
Echoing down the years
These are the conclusions of the PLOS One researchers in 2013:
- Gene expression profiles in ASD children with inflammatory bowel disorders distinguish them from normal controls
- CD and UC both display gene expression profiles that distinguish them from normal controls
- Gene expression profiles in children with ASD and inflammatory bowel disorders also distinguish them from children with CD and UC
And here is the main conclusion from Wakefield et al’s retracted 1998 Lancet case series: “We describe a pattern of colitis and ileal-lymphoid-nodular hyperplasia in children with developmental disorders…the connection is real and reflects a unique disease process”.
The similarities speak for themselves.
Although the PLOS One authors are careful to admit that further research is needed to confirm their results, and concede that their findings in ASD children may simply reflect an early phase of development of non-ASD-associated inflammatory bowel disease, their findings are hugely compelling. The evidence is mounting that there was very little wrong with the science performed by Andrew Wakefield’s group in 1998, and that an enormous effort was mounted to discredit him because of the threats his work presented to powerful interests. The sooner this truth is communicated to, and understood by, the public – the better.
 Wakefield AJ. Waging War on the Autistic Child. 2012 Skyhorse Publishing NY, NY. Chapter 2, footnotes 2–11, pp. 255–6.