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Research Developments in Genetics
The session opened with an overview of Genomics in CFS by Jonathon Kerr (London, UK). 88 CFS associated genes have been identified by microarray. 85 are upregulated and 3 downregulated. Several other diseases have also been looked at. Clustering has identified 7 subtypes in the 55 patients studied, and 5 genes showed therapeutic potential. Experimentally licensed drugs are being trialed and shown to be beneficial. These include some of the cancer and rheumatic drugs.
Microbial infections are associated with CFS, and it is hypothesized that specific organisms maybe associated with the subgroups. A trial of 62 patients (including 6 with Q fever) was undertaken. There were 14 with endogenous depression and 29 normal blood donor controls. Differential expression was seen for all 88 genes in the patient group. Similar genes were seen in the Q fever group. The depressed patients were similar to the normals except for 5 upregulated genes. The 62 new patients were clustered with the 55 previously tested CFS patients. 8 subtypes were identified. 12 of the genes were modulated by EBV protein. 10 of the 12 relate to the subtypes.
Future work needs to look at larger cohorts, longer term studies and biological relevance of the subtypes.
Marc Fremont (Brussels Belgium) reported on gene polymorphism, studies of which support the implication of intestinal dysfunction and activation of the Th17 axis in CFS. This opens a new perspective regarding treatment. The hypothesis that immune activation is mediated by Th17 cells in these patients is supported. There was a higher frequency of alleles making these patients more susceptible to gram negative enterobacteria.
Toni Whistler (Atlanta, USA) used gene arrays to look at the mediators of NK cell function. She found that there was decreased functional capacity of NK cells in Gulf War Illness. There was impaired immune function involving Th2 and pro-inflammatory cytokines, cytokines, cytotoxic NK cells and T cells, and dysregulated mediators of the stress response such as salivary cortisol. These differences were augmented by exercise challenge. Laboratory diagnostic tests maybe developed as a result of this research.
Further work from St George's, London was presented by Robert Petty (London, UK) who had looked at microRNA patterns in CFS. MiRNA expression was analyzed in PBMC samples for 15 patients and 30 normals. Microarray analysis identified differential expression of 63 miRNA, 13 of which were confirmed using Taqman QPCR. Using this method, each of the 13 showed elevated expression in CFS with increases over 1.5 fold compared to controls. There is potential for this to be used as a biomarker.
Lihan Zhang (London, UK) discussed their gene database of 117 CFS patients. The 8 genomic subtypes had distinct differences in SF-36 scores, clinical phenotypes, severity and geographical distribution. Antibody testing was done for EBV, enterovirus, Chlamydia pneumoniae, coxiella burnetii and parvovirus B19 an revealed subtype-specific relationships for EBV and enterovirus - both being common triggers in CFS. There is potential for treatment and further study is warranted.
A genome wide study of CFS identified candidate genes not considered in previous studies and was discussed by Mangalathu Rajeevan (Atlanta, USA). Polymorphisms were found to correlate with gene expression and were strong predictors of disease, and need further investigation.
Judy Mikovits (Reno, USA) concluded that preliminary data suggests that HLA and KIR variation might contribute to the risk of CFS. If HLA is not expressed, NK cells kill the target (viral infected) cells.
Andrew Lloyd (Sydney, Australia) found that cytokine polymorphisms have a synergistic effect on the severity and duration of acute infective illnesses and PIFS. Analysis of samples from 300 patients who had had EBV, Q fever and Ross River Virus (from the Dubbo Infection Outcomes Study) were analyzed. High producing IFNγ+874 T/A and low producing IL10-592C/A polymorphisms were both significantly associated with increasing illness severity. Variations in intensity of the inflammatory response underpin the severity of acute illness and can predict the duration of PIFS across varied infections. He stressed the importance of looking at phenotypes prospectively. The Dubbo study found no evidence of persistent antigen or chronicity of cytokines.