To identify the risk factors being associated with aetiology of amyotrophic lateral sclerosis (ALS), a series of systematic reviews based on existing observational epidemiological studies identified through searching of bibliographic databases were conducted. Associations between ALS and a number of genetic and environmental risk factors were examined using meta-analysis. Specifically we found that previous exposure to lead, pesticides, solvents, experience of trauma and electric shock were associated with relative increased risks of developing ALS of 86% [odds ratio (OR) =1.86, 95% CI: 1.39-2.48], 57% (OR=1.57,95% CI: 1.19-2.08), 47% (OR=1.47, 95%CI: 1.13-1.80), 64% (OR=1.64; 95%CI: 1.36-1.98), and 2.27% (OR=3.27, 95%CI:1.87-5.73) respectively, compared to their corresponding controls. The presence of intermediate CAG repeat expansion in the ATXN2 gene was associated with a 4.4 -fold increase in the risk of ALS (OR=4.44, 95%CI: 2.91-6.76). However, the attributable risk associated with each identified risk factor was estimated to be less than 5% of all ALS cases. These results confirm that ALS is a rare multifactorial degenerative condition of motor-neurons.

Abstract The purpose of this study was to determine the prevalence and aetiology of childhood hearing impairment (HI) in northern Finland and to evaluate the presence of additional disabilities among hearing impaired children. Such data would be valuable in guiding examinations and rehabilitation. Study I consisted of 214 children with mild to profound HI ascertained prior to age 10 years. They belonged to the birth cohort spanning the years 1993–2002. The clinical data were collected from the patient records of the Oulu University Hospital. In studies II–III, mutations in mitochondrial DNA (mtDNA) and in the WFS1 gene were determined in children with unknown aetiology of HI. Study IV is a prospective follow-up study examining the hearing of children with m.1555A>G mutation in mtDNA. The prevalence of childhood HI was 2.3/1000 live births. Genetic causes were the most common (47%) aetiology of HI, while 16% of cases were acquired and 36% were unknown. Almost 40% of 214 children had one or more additional disabilities that adversely influenced their development or learning. The frequency of additional disabilities was not associated with the severity of HI. Children with acquired HI had additional disabilities more often (66%) than children with genetic or unknown aetiology of HI (44%). Molecular analysis revealed that mutations in mtDNA and WFS1 are rare causes of childhood HI. Three rare variants and the novel p.Gly831Ser variant were found in WFS1. The p.Gly831Ser variant may be a new member to the group of heterozygous WFS1 mutations that lead to HI. One child harboured the pathogenic m.1555A>G mutation in MT-RNR1. In addition, eight rare variants and 13 polymorphisms were found in MT-RNR1 or in MT-RNR2. Evaluation of m.990T>C suggested that this transition is a pathogenic rather than a neutral variant. During a 7.8 year follow up of 19 children with m.1555A>G, HI was ascertained in 10 children (age range, 2.1–13.2 years at the end of the follow-up). Distinct phenotypes of HI were identified. Environmental factors contributing to the phenotype variation were not recognized. Because these children generally pass the newborn hearing screening, it is important to follow over time the hearing of children in families with the m.1555A>G mutation. / Tiivistelmä Tämän työn tavoitteena oli tutkia lapsuusiän kuulovikojen esiintyvyyttä ja etiologiaa pohjoissuomalaisilla lapsilla sekä selvittää kuulovikaisilla lapsilla esiintyviä muita oireita. Tieto kuulovian etiologiasta ja mahdollisista muista oireista auttaa tutkimusten ja kuntoutuksen suunnittelussa. Tutkimukseen osallistuvat lapset olivat syntyneet Pohjois-Suomessa vuosina 1993–2002. Osatyössä I kerättiin sairauskertomustiedot niistä lapsista, joiden kuulovika oli todettu ennen kymmenen vuoden ikää. Osatöissä II ja III määritettiin mitokondrion DNA:n ja tuman WFS1-geenin muutoksia lapsilla, joiden kuulovian etiologia oli tuntematon. Osatyössä IV seurattiin lasten kuuloa suvussa, jossa on todettu mitokondrion DNA:n mutaatio m.1555A>G. Lapsuusiän kuulovikojen esiintyvyys oli 2,3 tuhatta vastasyntynyttä kohden. Kuulovian yleisin syy oli perinnöllinen (47 %). Hankinnaisia kuulovikoja oli 16 % ja etiologialtaan tuntemattomia 36 %. Lähes 40 %:lla 214 lapsesta oli kuulovian lisäksi yksi tai useampi muu oire, jonka arvioitiin vaikuttaneen haitallisesti lapsen kehitykseen tai oppimiseen. Muiden oireiden esiintyminen ei riippunut kuulovian vaikeusasteesta. Hankinnaiseksi luokiteltuihin kuulovikoihin liittyi enemmän muita oireita (66 %) kuin niihin kuulovikoihin, joiden syy oli perinnöllinen tai tuntematon (44 %). Pohjoissuomalaisilla lapsilla mitokondrion DNA:n ja WFS1-geenin muutokset olivat harvinaisia kuulovian syitä. WFS1-geenissä todettiin kolme aikaisemmin tunnettua harvinaista ja yksi uusi geenimuutos. Tämän p.Gly831Ser-mutaation arvioitiin olevan heterotsygoottisena kuulovikaa aiheuttava muutos. Yhdellä lapsella todettiin mitokondrion DNA:n patogeeninen mutaatio m.1555A>G. Lisäksi MT-RNR1- ja MT-RNR2-geeneissä todettiin 13 polymorfiaa, jotka kuuluvat normaaliin vaihteluun ja kahdeksan harvinaista muutosta, joista m.990T>C-muutos on todennäköisesti kuulovikaa aiheuttava. Seurantatutkimukseen osallistui 19 lasta, joilla oli m.1555A>G-mutaatio. Seuranta kesti 7,8 vuotta, ja sen aikana ilmaantui kuulovika 10 lapselle, joiden ikä tutkimuksen loppuessa oli 2,1–13,2 vuotta. Todetut kuuloviat olivat keskenään erilaisia. Vaihtelua selittäviä ympäristötekijöitä ei todettu. Lasten kuuloa on tärkeää seurata perheissä, joissa on m.1555A>G-mutaatio, koska lapset yleensä läpäisevät vastasyntyneen kuulonseulontatutkimuksen ja mahdollinen kuulovika kehittyy myöhemmin.

Magister Scientiae Dentium - MSc(Dent) / AIM:The aim of this study was to review the data available from the Department of Health(DOH), on pre-school paediatric patients treated under Dental General Anaesthesia(DGA), at public health facilities in the Western Cape (WC) in order to ascertain the type and nature of treatment provided.METHODOLOGY:This retrospective descriptive study reviewed the records on the Department of Health(DoH) Database of 16 732 pre-school patients treated under dental general anaesthesia in the period 1 January 2005 until 31 December 2007. A questionnaire was also completed telephonically with 22 dentists from the district dental health clinics.Summary descriptive statistics were calculated from data collected and comparisons were drawn between services available at the health districts and academic hospitals.RESULTS:Of the 58 255 procedures recorded for pre-school patients in the district health clinics in the Western Cape, 99.94% were for extractions provided and 0.5% for restorations.The average number of teeth extracted was 10.4 (SD ±3.9).The average rate of DGA per 1000 of the population was 1.06. Only 9% (2) of dentists at district clinics reported that pre-DGA prevention was provided and 5% (1) reported including post-DGA prevention. The Academic Hospital at Tygerberg Oral Health Centre was the only facility in the Western Cape that provided comprehensive dental treatment for pre-school patients which included restorations, extractions, pre and post DGA prevention. Red Cross Children’s Hospital provided treatment for pre-school patients under DGA that included extractions, pre- and post DGA, but no restorative treatment. CONCLUSION:The demand for DGA in pre-school patients in the WC was high. The lack of prevention associated with DGA in the public health service is the most likely reason the retreatment rate under DGA was reported by dentists as being 77%. There was an absence of protocol regarding DGA for pre-school patients in the public health service.RECOMMENDATIONS:Guidelines formulated were recommended for use in the public service for pre-school patients being treated under DGA and includes the provision of preventive interventions such as regular topical fluoride applications, oral hygiene instruction and dietary advice.

To identify the risk factors being associated with aetiology of amyotrophic lateral sclerosis (ALS), a series of systematic reviews based on existing observational epidemiological studies identified through searching of bibliographic databases were conducted. Associations between ALS and a number of genetic and environmental risk factors were examined using meta-analysis. Specifically we found that previous exposure to lead, pesticides, solvents, experience of trauma and electric shock were associated with relative increased risks of developing ALS of 86% [odds ratio (OR) =1.86, 95% CI: 1.39-2.48], 57% (OR=1.57,95% CI: 1.19-2.08), 47% (OR=1.47, 95%CI: 1.13-1.80), 64% (OR=1.64; 95%CI: 1.36-1.98), and 2.27% (OR=3.27, 95%CI:1.87-5.73) respectively, compared to their corresponding controls. The presence of intermediate CAG repeat expansion in the ATXN2 gene was associated with a 4.4 -fold increase in the risk of ALS (OR=4.44, 95%CI: 2.91-6.76). However, the attributable risk associated with each identified risk factor was estimated to be less than 5% of all ALS cases. These results confirm that ALS is a rare multifactorial degenerative condition of motor-neurons.

Introduction: Little is known about the aetiology of cancer in teenagers and young adults (TYA) aged 15-24 years, although in England, cancer is the most common cause of disease-related mortality in this age group. The most common cancers at this age are lymphomas, central nervous system (CNS) tumours and germ cell tumours (GCT). The commonest carcinomas seen at older ages including lung, breast, large bowel and prostate account for only 3-4% of TYA cancers. In this thesis I describe the incidence patterns of selected cancers in TYA and the variation seen with geography, time and in population subgroups. The focus is on CNS tumours, GCT and bone tumours as they either peak in incidence in TYA and/or contribute disproportionately to cancer related mortality in TYA. This will allow formulation of hypotheses regarding aetiology of cancer in this age group which can then be tested by further research. Methods: For the majority of the analysis, anonymised national cancer registration data from England on individual patients of all ages with newly diagnosed cancer between 1979 and 2003 were used. To contrast the incidence patterns in England with that of India, data from five Indian urban population based cancer registries were used for part of the analysis. Age, sex, site and histology specific incidence rates were calculated and expressed per million person years. All rates, where appropriate, were adjusted to the world standard population using direct methods. To explore the link of growth with development of osteosarcoma and Ewing sarcoma, a random-effects meta-analysis was undertaken on studies which investigated an association of these tumours with height at diagnosis. Results: The incidence of cancer in TYA overall in England exceeded that of India. This was also true for most individual sites including epithelial cancers of lung, colon/rectum, breast, ovary and cervix, and non-epithelial cancers including melanoma, Hodgkin lymphoma and testicular cancer. Notable exceptions to this pattern were cancers of the mouth, gall bladder and stomach (females only) where incidence was higher in India. In England, CNS tumours in TYA were a composite of pilocytic astrocytomas and embryonal tumours (representing tail end of childhood CNS tumours), pituitary tumours, nerve sheath tumours, high grade astrocytomas and meningiomas (representing early-onset of CNS tumours that peak in incidence in the 6th and 7th decade of life), and of CNS GCTs, pleomorphic xanthoastrocytomas and neurocytomas which show a peak incidence in TYA. Irrespective of site or histology, GCT in England showed a peak in incidence between ages of 10 to 39 years which was more marked in males. This however varied by site and the peak incidence was seen at 10 to 14 years in the CNS, 15 to 19 years in ovary, 25 to 29 in mediastinum & thorax and abdomen & pelvis, and 30 to 34 years in testicular tumours. Osteosarcoma and Ewing sarcoma were the predominant bone tumours in TYA in England and showed a distinct peak of incidence at 10 to 14 years age in females and a larger peak at 15 to 19 years age in males. The peak incidence of osteosarcoma of long bones of the lower limb was six times more than that at any other site while the peak incidence of Ewing sarcomas located in the bones of the central axis exceeded those in long bones of the lower limb. The average height of patients with osteosarcoma at diagnosis was found to be significantly above the average height of the reference population, at the 95% level. The association of greater height at diagnosis with Ewing sarcoma was also significant at the 95% level but much weaker. Conclusion: In this thesis I have explored the epidemiology of cancer in TYA using some of the established methodologies which have previously been used in advancing our knowledge of childhood and older adult cancers. These studies provide some clues to aetiology. Variation in environmental exposures and lifestyle factors between England and India can explain the majority of the differences in incidence patterns observed. Genetic predisposition to cancer along with carcinogen exposure could lead to early onset of some cancers generally seen in older adults. Regardless of site, the similarity in age-incidence patterns of GCT, suggests a common initiation of these tumours in embryonic/foetal life with variable rates of tumour progression as a result of local factors or events during postnatal and pubertal period. The incidence patterns of osteosarcoma along with the strong and consistent association with a greater height at diagnosis indicate that bone growth is important in the development of this tumour while different biological pathways which may be unrelated to growth could also be relevant for Ewing sarcoma.

Background Among adolescents and young adults with DSM-IV alcohol use disorders (AUDs), there are inter-individual differences in the speed of transition from initial alcohol use (AU) to AUD. AUDs are highly co-morbid with other mental disorders. The factors associated with rapid transition from first AU to AUD remain unknown and the role of mental disorders in rapid transitions is unclear. Given this background we examined (1) whether prior anxiety, mood, externalizing and non-alcohol substance use disorders are related to the risk and speed of transition from first AU to DSM-IV alcohol abuse (AA) and alcohol dependence (AD) and (2) whether early age of onset of prior mental disorders (PMDs) is a promoter of rapid transition. Method A total of 3021 community subjects (97.7% lifetime AU) aged 14–24 years at baseline were followed up prospectively for up to 10 years. AU and mental disorders were assessed with the DSM-IV/M-CIDI. Results Among subjects with lifetime AU, several PMDs, such as specific phobia, bipolar disorder and nicotine dependence, were associated with an increased risk of AUD independent of externalizing disorders. Associations of PMDs with the speed of transition to AUDs were mostly weak and inconsistent. Only social phobia and externalizing disorders were associated with faster transitions to AD even after adjustment for other PMDs. Earlier age of onset of PMD was not associated with rapid transition. Conclusions Mental disorders are associated with the risk of AUD. With the possible exception of social phobia and externalizing disorders, they do not promote rapid transition, even if they occur particularly early. Future research needs to identify factors relevant to rapid transition to AUD.

Thesis (MScMedSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Left ventricular hypertrophy (LVH) occurs when the cardiomyocytes in the left ventricle become enlarged by increasing in mass in response to haemodynamic pressure overload. This can either be attributed to a normal physiological response to exercise or can be the result of a maladaptive process or disease state, such as chronic hypertension. Hypertrophic cardiomyopathy (HCM) is the most common form of Mendelian-inherited cardiac disease. A defining characteristic thereof is primary LVH that occurs when there are no other hypertrophy-predisposing conditions present. Therefore, HCM provides a unique opportunity to study the molecular determinants of LVH in the context of a Mendelian disorder, instead of in more complex disorders such as hypertension. Over 1000 HCM-causing mutations in 19 genes have been identified thus far, most of them encoding sarcomeric proteins residing in the sarcomeric C-zone. However, for many HCM patients no disease-causing genes have been identified. Moreover, studies have shown phenotypic variation in presentation of disease in, as well as between, families in which the same HCM-causing mutation segregates. This has led many investigators to conclude that genetic modifiers of hypertrophy exist. The aim of the study was to identify novel plausible HCM-causing or modifier genes by searching for interactors of a known HCM-causing protein, namely titin. The hypothesis was that genes encoding proteins, which interact with proteins that are encoded by known HCM-causative genes, may also be considered HCM-causing or may modify the HCM phenotype. To this end, the aim was to identify novel interactors of the 11-domain super-repeat region of titin, which resides within the sarcomeric C-zone, using yeast two-hybrid analysis. Five putative interactors of the 11-domain super-repeat region of titin were identified in this study. These interactions were subsequently verified by colocalisation in H9C2 rat cardiomyocytes, providing further evidence for possible interactions between titin and these proteins. The putative interactor proteins of titin determined from the Y2H library screen were: filamin C (FLNC), phosphatidylethanolamine-binding protein 4 (PEBP4), heart-type fatty acid binding protein 3 (H-FABP3), myomesin 2 (MYOM2) and myomesin 1 (MYOM1). The FLNC gene could be a candidate for cardiac diseases, especially cardiomyopathies that are associated with hypertrophy or developmental defects. The putative interaction of titin and PEBP4 is speculated to be indicative of the formation of the interstitial fibrosis and myocyte disarray seen in HCM. Heart-type fatty acid-binding protein 3 has prognostic value to predict recurrent cardiac events. Its suggested interaction with titin is speculated to play a role in inhibiting its functional abilities. Myomesin 2 is jointly responsible, with MYOM1, for the formation of a head structure on one end of the titin string that connects the Z and M bands of the sarcomere. This is speculated to be linked to a developmental error with the result being a defect in sarcomeric structure formation, which could result in pathologies such as HCM. Therefore, these identified proteins could likely play a functional role in HCM due to their interactions with titin. This research could thus help with new insights into the further understanding of HCM patho-aetiology. / AFRIKAANSE OPSOMMING: Linker ventrikulêre hipertrofie (LVH) ontstaan wanneer die kardiomyosiete in die linkerventrikel vergroot as gevolg van 'n verhoging in massa in reaksie op hemodinamiese drukoorlading. Dit kan toegeskryf word aan 'n normale fisiologiese respons op oefening of kan die gevolg wees van 'n wanaangepaste of siektetoestand, soos chroniese hipertensie. Hipertrofiese kardiomiopatie (HKM) is die mees algemene vorm van Mendeliese oorerflike hartsiekte. 'n Bepalende eienskap daarvan is primêre LVH, wat plaasvind wanneer daar geen ander hipertrofie-predisponerende voorwaardes teenwoordig is nie. Gevolglik bied HKM 'n unieke geleentheid om die molekulêre derterminante van LVH te bestudeer, in die konteks van 'n Mendeliese oorerflike siekte, in plaas van om dit in die meer komplekse siektes soos hoë bloeddruk te bestudeer. Meer as 1000 HKM-veroorsakende mutasies is tot dusver in 19 gene geïdentifiseer. Die meeste van hulle kodeer vir sarkomeriese proteïene wat in die C-sone voorkom. Egter, vir baie HKM-pasiënte is geen siekte-veroorsakende gene al geïdentifiseer nie. Daarbenewens het studies getoon dat variasie in fenotipiese aanbieding van die siekte in, sowel as tussen, families voorkom wat dieselfde HKM-veroorsakende mutasie het. Dit het daartoe gelei dat baie navorsers tot die gevolgtrekking gekom het dat genetiese wysigers van hipertrofie wel bestaan. Die doel van die studie was om nuwe moontlike HKM-veroorsakende of wysiger-gene te identifiseer deur te soek vir interaktors van 'n bekende HKM-veroorsakende proteïen, naamlik titin. Die hipotese was dat gene wat vir proteïene kodeer, wat in wisselwerking is met proteïene wat geïnkripteer word deur bekende HKM-veroorsakende gene, ook oorweeg kan word om HKM te veroorsaak. Dit kan ook die HKM fenotipe verander. Dus was die doel om nuwe interaktors van die 11-domein super-herhaalstreek van titin, soos gevind binne die sarkomeriese C-sone, te identifiseer deur middel van gis-twee-hibried-analise. Vyf vermeende interaktors van die 11-domein super-herhaalstreek van titin is in hierdie studie geïdentifiseer. Hierdie interaksies is later geverifieer met behulp van ko-lokalisering in H9C2-rotkardiomyosiete, wat verdere bewyse vir moontlike interaksies tussen titin en hierdie proteïene verskaf. Die vermeende interaktor-proteïene van titin wat bepaal is vanaf die gis-twee-hibried-biblioteeksifting was as volg: filamin C (FLNC), phosphatidylethanolamine-bindingsproteïen 4 (PEBP4), hart-tipe-vetsuur bindingsproteïen 3 (H-FABP3), myomesin 2 (MYOM2) en myomesin 1 (MYOM1). Die FLNC-geen kan 'n kandidaat vir kardiale siektes, veral kardiomiopatieë, wees wat geassosieer word met hipertrofie of ontwikkelingsafwykings. Die vermeende interaksie van titin en PEBP4 dui daarop om 'n aanduiding te wees vir die vorming van die interstisiële fibrose en miokardiale wanorde, soos gesien in HKM. Hart-tipe-vetsuur bindingsproteïen 3 het prognostiese waarde om herhalende kardiale gebeure te voorspel. Verder dui sy voorgestelde interaksie met titin moontlik daarop dat dit 'n rol kan speel in die inhibering van sy funksionele vermoëns. Myomesin 2 tesame met MYOM1 is verantwoordelik vir die vorming van 'n kopstruktuur aan die een kant van die titinstring wat dan die Z- en M-bande van die sarkomeer verbind. Daar word vermoed dat dit gekoppel is aan 'n ontwikkelingsfout, met die gevolg dat daar 'n defek is in sarkomeriese struktuurvorming, wat weer kan lei tot patologieë soos HKM. / Mrs Wendy Ackerman / Prof Paul van Helden / National Research Foundation (NRF) / Stellenbosch University

Parkinson's disease (PD) is a progressive, degenerative, neurological disease. The progressive disability associated with PD results in substantial burdens for those with the condition, their families and society in terms of increased health resource use, earnings loss of affected individuals and family caregivers, poorer quality of life, caregiver burden, disrupted family relationships, decreased social and leisure activities, and deteriorating emotional well-being. Currently, no cure is available and the efficacy of available treatments, such as medication and surgical interventions, decreases with longer duration of the disease. Whilst the cause of PD is unknown, genetic and environmental factors are believed to contribute to its aetiology. Descriptive and analytical epidemiological studies have been conducted in a number of countries in an effort to elucidate the cause, or causes, of PD. Rural residency, farming, well water consumption, pesticide exposure, metals and solvents have been implicated as potential risk factors for PD in some previous epidemiological studies. However, there is substantial disagreement between the results of existing studies. Therefore, the role of environmental exposures in the aetiology of PD remains unclear. The main component of this thesis consists of a case-control study that assessed the contribution of environmental exposures to the risk of developing PD. An existing, previously unanalysed, dataset from a local case-control study was analysed to inform the design of the new case-control study. The analysis results suggested that regular exposure to pesticides and head injury were important risk factors for PD. However, due to the substantial limitations of this existing study, further confirmation of these results was desirable with a more robustly designed epidemiological study. A new exposure measurement instrument (a structured interviewer-delivered questionnaire) was developed for the new case-control study to obtain data on demographic, lifestyle, environmental and medical factors. Prior to its use in the case-control study, the questionnaire was assessed for test-retest repeatability in a series of 32 PD cases and 29 healthy sex-, age- and residential suburb-matched electoral roll controls. High repeatability was demonstrated for lifestyle exposures, such as smoking and coffee/tea consumption (kappas 0.70-1.00). The majority of environmental exposures, including use of pesticides, solvents and exposure to metal dusts and fumes, also showed high repeatability (kappas &gt0.78). A consecutive series of 163 PD case participants was recruited from a neurology clinic in Brisbane. One hundred and fifty-one (151) control participants were randomly selected from the Australian Commonwealth Electoral Roll and individually matched to the PD cases on age (± 2 years), sex and current residential suburb. Participants ranged in age from 40-89 years (mean age 67 years). Exposure data were collected in face-to-face interviews. Odds ratios and 95% confidence intervals were calculated using conditional logistic regression for matched sets in SAS version 9.1. Consistent with previous studies, ever having been a regular smoker or coffee drinker was inversely associated with PD with dose-response relationships evident for packyears smoked and number of cups of coffee drunk per day. Passive smoking from ever having lived with a smoker or worked in a smoky workplace was also inversely related to PD. Ever having been a regular tea drinker was associated with decreased odds of PD. Hobby gardening was inversely associated with PD. However, use of fungicides in the home garden or occupationally was associated with increased odds of PD. Exposure to welding fumes, cleaning solvents, or thinners occupationally was associated with increased odds of PD. Ever having resided in a rural or remote area was inversely associated with PD. Ever having resided on a farm was only associated with moderately increased odds of PD. Whilst the current study's results suggest that environmental exposures on their own are only modest contributors to overall PD risk, the possibility that interaction with genetic factors may additively or synergistically increase risk should be considered. The results of this research support the theory that PD has a multifactorial aetiology and that environmental exposures are some of a number of factors to contribute to PD risk. There was also evidence of interaction between some factors (eg smoking and welding) to moderate PD risk.

Diss. (sammanfattning) Stockholm : Karol, inst., 2002. / Härtill 4 uppsatser.

Objectives: To assess the expression of the symptoms of jaw muscle pain and its association with alterations in biochemistry, other symptoms and the carriage of staphylococci. Methods: Three different study populations were assessed. The first was selected and examined by the author and consisted of 43 pain and 41 age and sex matched controls. The second was a study of CFS patients who were blinded to the author and the author subsequently examined the associations between jaw muscle symptom reporting and the standardised biochemistry measures. The third study was also blinded to the author but included an investigation of staphylococci and certain cytokine and biochemistry measures. Results: The three studies clearly establish an association between the carriage of toxicogenic coagulase negative staphylococci and the expression of jaw muscle pain in both males and females. These associations were homogeneous and were found whether the patients were selected on the basis of having jaw muscle pain or selected from within a population of patients selected on the basis of having Chronic Fatigue Syndrome. The studies associated the changes with variations in biochemistry and these were in turn associated with symptom expression within the jaw muscle pain patients. These biochemical alterations included the dysregulation of immune cell counts, cytokines, electrolyte and protein metabolism. These symptoms and biochemical changes were associated with pain severity and illness duration and staphylococcal toxin production. From the data a model was developed which shows the mechanisms involved in the development of chronic pain in the jaw muscles. Conclusions: The carriage of toxicogenic coagulase-negative staphylococci were found to be associated with the expression of jaw muscle pain and the alterations in biochemistry associated with these symptoms.