Background and aims. Early detection of Chronic Obstructive Pulmonary Disease (COPD) and secondary prevention by means of smoking cessation are the only available methods of stopping the progression of the disease. The overall aim was to examine the possibilities of early detection and prevention of COPD in General Practice. The specific aims were to evaluate a method of detecting COPD at its early stages, to investigate the rate of emphysema in smokers with normal lung function and smokers defined as preclinical COPD, to investigate the effects of performed spirometries and brief smoking cessation advice on smoking habits and to test if concentrations of certain biomarkers in blood, saliva and exhaled breath condensate (EBC) could identify subjects with COPD or non-COPD subjects supposed to be at risk of developing COPD. Methods. The first study evaluated an invitational method, which offered voluntary screening spirometry to a targeted population of smokers 40-55 years old. In the second follow-up study, all smokers with COPD and half of the smokers with normal lung function (NLF) were annually invited for spirometry and brief smoking cessation advice for a duration of 3 years, with half of the smokers with NLF being tested only last year. In the third study, 54 smokers with NLF were examined with High Resolution Computed Tomography (HRCT), with blood samples also being collected from each subject. In study four, 19 subjects categorised as having COPD, 30 non-COPD subjects and 15 healthy non-smoking volunteers were studied by means of spirometry, DLCO, and analysis of biomarkers in EBC, saliva and serum. Results. A total of 512 smokers responded. The prevalence of COPD was 27.5% and was classified as mild in 85% of the sufferers, moderate in 13% and severe in 2%. At year 1, 10% of the smokers with COPD had been continuously abstinent from smoking, compared to 2% of smokers with NLF. The prolonged abstinence rate increased yearly, and at year 3 the smoking cessation rates in smokers with COPD was 25% compared to 7% in smokers with NLF. By visual analysis, HRCT showed signs of emphysema in 43% of the subjects. Emphysema was also associated with low BMI. Higher serum concentrations of lysozyme and lower DLCO were recorded in those with COPD compared to non-COPD subjects. With the exception of chlorine, none of the remaining biomarkers were detected in EBC. Conclusions. By invitational targeted screening, COPD can be easily detected in its mild stages by using spirometry. By becoming diagnosed with COPD, smokers seem to be more motivated to stop smoking, and COPD patients should repeatedly be offered spirometry and smoking cessation advice which may prevent the progression of the disease to a severe disabling form. HRCT may detect smoke related parenchymal lung damage (i.e. emphysema) in symptom-free smokers with normal spirometry. Serum lysozyme and DLCO appeared to be the strongest discriminator between COPD and non-COPD subjects. The use of EBC as a tool to measure exhaled inflammatory biomarkers involved in COPD is as yet uncertain.

Crohn’s disease (CD) is believed to be initiated when an individual, who has agenetic predisposition either leading to a disturbance in the barrier functionand/or the innate immune system is exposed to triggering environmentalfactors, the most important being intraluminal bacteria. Genetic and functionalstudies have confirmed the Pattern-recognition receptors (PRRs), Nod2, TLR4and NALP3, as important mediators of the inflammatory process associatedwith disease progression. However, the mechanisms that link enteric bacteriaand barrier function in a background of genetic predisposition to CD are justbeginning to emerge. The general aim of this thesis was therefore to morethoroughly investigate the mechanisms of bacterial-epithelial interaction in CD. Here we present evidence suggesting that the small bowel is able to inducetranscytosis of antigens after short term exposure to Yersinia pseudotuberculosis. This suggests that small bowel enterocytes are able toattain follicle associated epithelial (FAE) abilities and contribute to the barrierdysfunction observed in CD. Furthermore we report a positive effect of anti-TNFα treatment (infliximab) on the translocation of adherent invasive E.coli (AIEC) across the colonic mucosa of patients suffering from severe CD. We also confirm the importance of the Nod-like receptors (NLRs) in thepathogenesis of CD by showing that combined polymorphisms in the genesencoding NALP3 and CARD8 confer susceptibility to CD among Swedish menand in addition to previous published results add a gender aspect on thegenotype-phenotype relationship in CD. Finally, we show that Nod2 is rapidlysubjected to ubiquitination followed by proteasomal degradation, henceproviding important clues about how NLR regulation might occur in the cell,suggesting that the ubiquitin-proteasome pathway is an important factor toconsider in the development of the disease. In conclusion we report novel insights into the bacterial-epithelial interactionsoccurring in CD and contribute important clues about the origin of this disease.ISBN: 978-

Diet has for many years been known to play a key role in the development of chronic diseases. There are clear associations between consumption of vegetables, fruits and berries, and risk of cardiovascular diseases, the number one cause of death in the world. To maintain homeostasis of the vascular wall the balance between angiotensin II, nitric oxide and reactive oxygen species is of great importance in order to affect the development of cardiovascular diseases. Angiotensin II, a potent vasoconstrictor causing cell growth and nitric oxide, a signalling molecule influencing the vascular system as a vasodilatator, inhibiting cell proliferation and reactive oxygen species, are linked together in the renin-angiotensin aldosteron system. Angiotensin-converting enzyme will as a key enzyme in the reninangiotensin aldosteron system convert angiotensin I to form angiotensin II and nitric oxide is known to inhibit angiotensin-converting enzyme and act as a scavenger of reactive oxygen species. Plant-derived substances as flavonoids, tocopherols and carotenoids are shown to have beneficial effects on the cardiovascular system due to their antioxidative effects. The aims of this study were to investigate beverages, dietary products, herbal medicinal plants, α-tocopherol, β-carotene, sterols and lipidowering drugs on angiotensin-converting enzyme activity and nitric oxide concentrations. This was done to investigate if the sole mechanism of plant-derived substances is their antioxidative properties and to investigate if there is any connection between effect and biosynthesis/structure of plant substances. The tested infusions and extracts containing high amounts of flavonoids, the flavonoids and β-carotene significantly inhibited angiotensin-converting enzyme activity in vitro. The other substances tested did not affect, or in some cases significantly increased, angiotensin-converting enzyme activity. The infusions and extracts containing high amounts of flavonoids, the flavonoids andβ-carotene showed an increase on nitric oxide concentrations in vitro. Oral intake of a single dose of Rooibos tea significantly inhibited angiotensin-converting enzyme activity. A significant inhibition of angiotensin-converting enzyme activity was seen with the green tea for the angiotensin-converting enzyme genotypes II and ID. A significant inhibition of angiotensin-converting enzyme activity was also seen with the Rooibos tea for the angiotensin-converting enzyme genotype II. Conclusion; flavonoids and β-carotene interact with the cardiovascular system in severalways, by reducing reactive oxygen species (as shown in several studies), increasing nitricoxide concentrations (as shown here and by others) and also by inhibiting angiotensinconvertingenzyme activity (as shown here). Infusions and extracts as tea containing highamounts of flavonoids function as angiotensin-converting enzyme inhibitors. Angiotensinconvertingenzyme contains two zink-dependent catalytic domains and angiotensinconvertingenzyme inhibitors are designed to bind to the Zn2+ at the active site. If theinhibitory mechanism of flavonoids on angiotensin-converting enzyme activity is due to theirability to bind to Zn2+ ions then it would be possible for the flavonoids to also inhibit otherzinc metallopeptidases, i.e. endothelin-converting enzyme, matrix metallopeptidases, neutralendopeptidase and maybe insulin-degrading enzyme, thereby exerting several additionalpositive effects on the cardiovascular system. / 2009

Cardiovascular disease is the leading cause of death in western societies and endothelial dysfunction is one of the earliest signs seen in the development of such conditions. Thedevelopment of prognostic tools to aid in the prediction of micro- and macrovascular diseasebased on assessment of vascular reactivity is therefore of paramount importance. Transdermal iontophoresis offers a quick, non-invasive and relatively straightforward way todeliver vasoactive substances in order to provoke a vascular response in man. When combined with either laser Doppler flowmetry (LDF) or tissue viability imaging (TiVi) for quantification of these responses the methodology offers a potentially powerful tool forvascular investigations. The technique has, however, not been established in clinical practice yet and is mostly used in experimental settings. The lack of consensus in what data analysistechnique to use, uncertainty concerning the actual drug dose applied, and the difficulties associated with the assessment of responses to vasoconstrictors may have contributed to thisfact. The aim of this thesis is therefore to address these issues and thus facilitate the use and improve the applicability of transdermal iontophoresis for assessment of cutaneous microvascular function. More specifically, a non-linear dose-response model (Emax-model) that is commonly used in in vitro investigations of vascular function was applied to the iontophoresis data. The resultsshow that the Emax-model accurately describes the cutaneous vascular responses totransdermally iontophoresed acetylcholine (ACh) and, sodium nitroprusside (SNP). The Emaxmodelgenerates variables that can be used for quantitative statistical analysis of data andenables a more powerful analysis compared to the methods presently used. It is furtherdemonstrated that the maximal dose effect and vascular responses vary between differentprotocols with the same total iontophoretic charge but with different current strengths anddurations. This finding implies that the assumption that the local drug dose is linearlyproportional to the iontophoretic charge (used for estimation of delivered drug dose to themicrovascular bed) may be inaccurate in in vivo investigations and that there is need for amore refined model. It is also demonstrated that in a vasoconstrictive setting (iontophoresis of noradrenaline andphenylephrine) TiVi is the favourable technique for measuring vascular responses as it issensitive enough to generate data that can be fitted to the Emax-model even without predilatationof the vessels.

Neuronal plasticity means the ability of the brain, its cells and networks to adapt and adjust to new challenges, a process which is ongoing throughout life. The goal of this thesis was to gain better understanding of the molecular events that follow different types of stimulations of brain structures such as the hippocampus, a key region for cognitive functions with overriding control on the corticosteroid system. A better knowledge of the mechanisms involved in neuronal plasticity is fundamental in the development of strategies for improving health in patients suffering from major depression or cognitive disorders such as Alzheimer’s disease. Antidepressant drugs induce the expression of several genes involved in neuronal plasticity, a mechanism which may explain the several weeks time lag between treatment initiation and clinical effect commonly observed in patients. Besides, there are indications that disturbances in the corticosteroid system are involved in the pathogenesis of major depression. Therefore, the mRNA expression of the glucocorticoid receptors (GR) and mineralocorticoid receptors (MR) as well as of the immediate-early genes NGFI-A and NGFI-B was analyzed using in situ hybridization in the hippocampus and cortex after 21 days treatment with various antidepressant drugs having different monoaminergic profiles. The mRNA expression of the transcription factors was selectively increased depending on region and also on the monoaminergic profile of the drug given. Generally, drugs with less specificity for monoamines had an overall more anatomically wide-spread inducible effect. In a follow-up study the message expression of the synaptic protein NP2 was investigated in a similar setting where long-term (21 days) was compared with short-term (3 days) antidepressant treatment. In addition to the hippocampus, the medial habenula, a relay station within the limbic system was analyzed. Overall there was an upregulation of NP2 mRNA expression following long-term treatment irrespective of the monoaminergic profile of the drug. Simultaneously, NP2 mRNA was analyzed in rats exposed to enriched, normal or deprived environments respectively, an experimental setting known to affect neuronal plasticity. However, in contrast to the pharmacological treatment, this environmental stimulation did not lead to alterations in NP2 mRNA expression in any of the regions studied. Finally, the function of NP2 as well as the closely related proteins NP1 and NPR was investigated. The “knock-out mouse” technique was used to eliminate these neuronal pentraxins (NPs), both individually and in various combinations. Since previous data had suggested that the NPs are involved in synaptic development, axonal refinement in the visual system during development was analyzed in these animals. In the NP1/NP2 knock-out mice, synaptic formation, axonal development and refinement occurred at a significantly slower rate than in wild-type mice, indicating that the NPs may be necessary for activity-dependent synaptogenesis. In conclusion, the results of the studies constituting this thesis demonstrate that long-term treatment with antidepressant drugs, possessing different monoaminergic profiles, has selective effects on the expression of NGFI-A, NGFI-B, GR and MR in the mammalian brain. In general, the least selective drugs exhibit the most profound effect suggesting that induction of neuronal plasticity is more effective with multiple neuronal inputs. The results also show that NP2 expression is induced by antidepressant drugs, in contrast to environmental stimulation, supporting the presence of different pathways for inducing neuronal plasticity depending on type of stimuli. Finally, this thesis indicates that the neuronal pentraxins play an important part in synaptic development.

Normal human cells are strictly controlled in their environment by extrinsic and intrinsic factors. Despite this, some cells begin to develop into cancer cells, and if this process is allowed to continue, it will develop into cancer disease. To become cancerous, a cell must break several biological barriers. Two important barriers are apoptosis and cellular growth control. Cancer is a multifactorial disease caused by environmental and hereditary factors. The incidence of colorectal cancer varies among different populations around the world. Sweden has a history of a relatively high incidence of colorectal cancer, whereas its incidence in China is relatively low. Nuclear factor kappa B (NF-κB) is a transcription factor protein family, regulating genes involved in several aspects of cancer development. In human cells five members have been identified: NFKB1 (p105/p50), NFKB2 (p100/p52), RelA (p65), RelB and c-Rel. They normally form homo- or heterodimers in the cytoplasm of the cells, where they are in an inactive state by binding to inhibitory proteins, I kappaB-α, -θ and -ε and Bcl-3. Stimulatory signals, both intrinsic and extrinsic, lead the inhibitory proteins to be phosphorylated, which marks them for degradation. On activation, NF-κB proteins are often posttranslationally modified. In the first project, we investigated the role of a polymorphism in the promoter region of NFKB1 gene. The polymorphism is a 4-basepair insertion/deletion located 94 basepairs upstream of the gene (-94ins/delATTG). It does not seem to alter the amino acid sequence of the protein and therefore does not alter the function of the protein itself. Instead, it alters the regulation of the protein transcription. The aim of the present study was to investigate whether the polymorphism was related to cancer risk or clinicopathological variables. We found that this polymorphism increased the risk of sporadic colorectal cancer in a Swedish population but not in Swedish populations with a family history of colorectal cancer or in Chinese population. In the second project we studied an 8-basepair insertion/deletion polymorphism in the promoter region of NFKBIA gene coding for the nuclear factor kappa B inhibitory protein, IκBα. This polymorphism is located 708 basepairs upstream of the gene (-708ins/del8). The aim of the study was to investigate whether the polymorphism was related to cancer risk or clinicopathological factors. We found that this polymorphism was very rare in a Swedish population of colorectal cancer patients and controls and was totally absent in a Chinese population of patients and controls. Our conclusion is that this polymorphism is too rare to have a major impact on colorectal cancer incidence in the two populations. In the third project we studied levels of p65 phosphorylated at Serine-536 in colorectal cancers in a Swedish population. After activation and IκB phosphorylation/degradation, p65 is phosphorylated at Serine-536. This phosphorylation is involved in regulating transcriptional activity, nuclear localisation and protein stability. The aim of the study was to investigate whether the expression of the phosphorylated protein correlated to any clinicopathological variables, including survival. The expression of p65 phosphorylated at Serine-536 increased from normal mucosa to primary tumour, but no further increase to lymph node metastases was found. We did find, however, that the strong expression in the cytoplasm was correlated to worse survival among the patients, independent of gender, age, tumour location, stage and differentiation. In the fourth project we continued to study p65 phosphorylated at Serine-536. In this project, however, we studied the expression in a population of rectal cancer patients who participated in a Swedish clinical trial of preoperative radiotherapy. The aim of the study was to investigate whether the expression correlated to response to radiotherapy or to clinicopathological and some biological factors. We found that the expression was increased from normal mucosa to primary tumour, but detected no further increase from primary tumour to lymph node metastases. We found that the expression of p65 protein phosphorylated at Serine-536 was positively related to expression of TEM1, FXYD-3, PRL, p73 and MAC30 in the group of patients who received radiotherapy. Although no such relationship was seen in the group of patients that had not received radiotherapy, we did not find that the expression of p65 protein phosphorylated at Serine-536 was directly related to the clinical response to radiotherapy. In summary, the -94ins/delATTG polymorphism in the promoter region of NFKB1 gene increases the risk of sporadic colorectal cancer in Swedish but not in Chinese populations. The -708ins/del8 polymorphism in the promoter region of the NFKBIA gene is too rare to have a major impact on colorectal cancer incidence in Swedish and Chinese populations. Strong expression of p65 protein phosphorylated at Serine-536 is independently related to worse survival in Swedish colorectal cancer patients, and the expression is positively correlated to biological factors associated with more malignant features of tumours in rectal cancer patients who received preoperative radiotherapy.

Mycobacterium avium belongs to a group of over 130 species of non-tuberculous mycobacteria (NTM) or environmental mycobacteria. The subspecies Mycobacterium avium avium was originally described as the causative agent of bird tuberculosis, but was later found to cause disease also in humans. Small children display a special form of infection that is seldom detected in other age groups. It manifests as a chronic lymphadenitis usually in the head and neck region. The incidence rate is approximately 1-5/100,000 children/year. However, exposure to this bacterium is high as judged by sensitin skin test studies. Even if a lot of persons are infected with M. avium, a majority of them do not develop disease and the bacterium is therefore considered to be of low virulence, causing disease mainly in immunocompromised persons. Children with M. avium lymphadenitis, however, usually do not have any known deficiencies in the immune system. This thesis elucidates why small children are prone to develop disease by M. avium. Investigation of a possible zoonotic spread of this bacterium to children involved analysis and comparison of different strains isolated from birds and other animals and from children, using the restriction fragment length polymorphism (RFLP) method on insertion sequence IS1245, resulting in the finding that the children were infected exclusively with the new proposed subspecies M. avium hominissuis. Animals in general and birds in particular were infected with the subspecies M. avium avium (using the more narrow definition). Moreover, when investigating the immunological response of human peripheral blood mononuclear cells (PBMCs) to stimulation with M. avium hominissuis and M. avium avium, respectively, it was found that the former subspecies induced lower IFN-γ and IL-17 than the latter, but higher levels of Il-10, which might contribute to explain the higher pathogenicity of M. avium hominissuis in humans. Through studies of the geographical distribution of cases of M. avium infection in children in Sweden and the seasonal variation of the disease, a fluctuation of the incidence over the year was detected, with higher numbers of cases in the autumn months and lower numbers in the late spring. There was a higher incidence rate in children living close to water than in those living in the inland or in the urban areas. Therefore, outdoor natural water is the most probable source of infection in children with M. avium lymphadenitis. Through a descriptive clinical retrospective study, complete surgical removal of the affected lymph node was found to lead to better results than treatment by incision and drainage of abscess or expectation only. Finally there might be several explanations as to why an individual develops disease after infection with M. avium, such as, exposure, bacterial virulence factors or possible specific deficiencies of the immune system of the host or a combination of these factors. Which are the more important factors regarding children with M. avium lymphadenitis is still an open question.

The juxtaglomerular apparatus (JGA) is a control unit of the kidney, that regulates glomerular filtration rate (GFR) and renin release, and hence extracellular volume and blood pressure. The tubuloglomerular feedback (TGF) mechanism is a negative feedback loop that regulates GFR. Neuronal nitric oxide synthase (nNOS) is highly expressed in the macula densa cells of the JGA, and regulates the sensitivity of the TGF mechanism. Hypertension has been proposed to be caused by an increased sensitivity of the TGF due to nNOS deficiency. In diabetes, reduced TGF activity due to increased sodium-glucose reabsorption is suggested to cause hyperfiltration. Glomerular hyperfiltration has clinical significance, since it correlates with the risk of developing nephropathy. In this thesis, the role of nNOS in the control of blood pressure and renin release was investigated in nNOS knockout mice (nNOS-/-) treated with low- and high sodium diets. The nNOS-/- were normotensive, but displayed an impaired renin regulation, and failed to increase renin in response to a low sodium diet. A significantly larger renin increase during phosphodiesterase 3 (PDE3) inhibition was found in nNOS-/- compared to the wild types, resulting in similar renin levels. Furthermore, the role of TGF and proximal glucose reabsorption in diabetes-induced hyperfiltration was investigated in adenosine A1-receptor knockout mice (A1AR-/-) that are known to lack a functional TGF mechanism. Diabetes was induced in A1AR-/- and wild types by injection of alloxan. The diabetic A1AR-/- displayed a similar degree of hyperfiltration as their wild-type controls. Inhibition of renal sodium-glucose transporters reduced GFR in both genotypes, but the reduction was even more pronounced in the A1AR-/-. In conclusion, the results indicate that renin secretion during low sodium conditions is mediated by nNOS-derived nitric oxide via cGMP-mediated inhibition of PDE3, whereas deletion of the nNOS gene does not cause hypertension. Diabetes-induced hyperfiltration is not mediated by TGF, but appears to be dependent on increased renal glucose reabsorption.

Background: Focal atrial tachycardias are tachycardias characterized by a radial spread of activation from a discrete area of the atrial myocardium. They account for 10-15% of supraventricular tachycardias and are generally poorly responsive to pharmacological treatment. The pathophysiologic substrate of these arrhythmias remains poorly understood. Computational studies suggest that a certain degree of intercellular uncoupling and anisotropy are important prerequisites for the development of focal arrhythmias. The anisotropy and intercellular uncoupling could promote focal arrhythmias by minimizing the suppressive effect of the surrounding atrial muscle on the pacemaking process in the focus. This hypothesis would be in agreement with the fact that fractionated electrograms, a marker of anisotropy and reduced intercellular coupling, are often recorded at the site of earliest activated site. Reduced intercellular coupling could be induced by factors enhancing the amount of intracardiac connective tissue, such as advancing age or cardiac disease states. Indeed, focal inflammatory processes have been reported in atrial specimens resected from patients with focal tachycardia undergoing arrhythmia surgery. Methods: In a group of patients with paroxysmal and permanent atrial fibrillation we sought to assess whether there is a link between inflammation and the occurrence of atrial arrhythmia. We therefore analyzed different inflammatory markers (C-reactive protein and interleukin-6 and 8) in the systemic and pulmonary circulation as well as in the heart in these patients. In addition, we assessed the extent of intercellular uncoupling in the vicinity of tachycardia origin in patients with focal atrial tachycardia. We also assessed the impact of electrogram fractionation on the method of activation time determination, by comparing different methods for estimating activation time with regard to the appearance of the resultant activation maps and the location of the foci. We also assessed the observer variability in the estimation of activation time during mapping of these tachycardias. Results: There was no evidence of elevated circulatory levels of inflammatory markers in patients with paroxysmal atrial fibrillation. However, patients with permanent atrial fibrillation had increased levels of inflammatory markers (interleukin-8) in the systemic circulation but not in the pulmonary circulation or in the heart. In patients with focal atrial tachycardia, a higher degree of electrogram fractionation existed in the region surrounding the earliest activation site and activated within the first 15 ms as compared with the remaining atrium. Moreover, within this region, from the periphery towards the earliest activated site, there was a gradual increase in electrogram fractionation as well as a gradual decrease in the peak-to-peak voltage. When comparing different methods for estimating local activation time we found that different methods can generate activation maps with different appearances and foci with different locations. However, regardless of the method of activation time determination, the foci tend to cluster within relatively large areas of low-amplitude fractionated electrograms. In addition we found significant observer variability in the estimation of the local activation time. Conclusion: Patients with paroxysmal atrial fibrillation (and probably focal atrial tachycardia) do not have elevated levels of inflammatory markers. The increased levels of interleukin-8 in the systemic circulation suggest a link between long-lasting arrhythmia and inflammation. A relatively wide area of increased electrogram fractionation exists around the site of origin of focal atrial tachycardia. These findings suggest a sizeable atrial region with particular electrophysiological proprieties and raise the possibility of an anatomical substrate of the tachycardia. Increased electrogram fractionation can impact the process of activation determination, as suggested by the fact that different methods compute foci with different locations. In addition, there is significant observer variability in the estimation of local activation time in these patient. / Article II and III are the same article while article III is linked to the corrected article and article II to the original article.

DNA has become a powerful forensic tool for solving cases such as linking a suspect to a crime scene, resolving biological relationship issues and identifying disaster victims. Traditionally, DNA investigations mainly involve two steps; the establishment of DNA profiles from biological samples and the interpreta-tion of the evidential weight given by theses DNA profiles. This thesis deals with the latter, with focus on models for assessing the weight of evidence and the study of parameters affecting these probability figures. In order to calculate the correct representative weight of DNA evidence, prior knowledge about the DNA markers for a relevant population sample is required. Important properties that should be studied are, for example, how frequently certain DNA-variants (i.e. alleles) occur in the population, the differences in such frequencies between subpopulations, expected inheritance patterns of the DNA markers within a family and the forensic efficiency of the DNA markers in casework. In this thesis we aimed to study important population genetic parameters that influence the weight of evidence given by a DNA-analysis, as well as models for proper consideration of such parameters when calculating the weight of evi-dence in relationship testing. We have established a Swedish frequency database for mitochondrial DNA haplotypes and a haplotype frequency database for markers located on the X-chromosome. Furthermore, mtDNA haplotype frequencies were used to study the genetic variation within Sweden, and between Swedish and other European populations. No genetic substructure was found in Sweden, but strong similari-ties with other western European populations were observed. Genetic properties such as linkage and linkage disequilibrium could be im-portant when using X-chromosomal markers in relationship testing. This was true for the set of markers that we studied. In order to account for this, we pro-posed a model for how to take linkage and linkage disequilibrium into account when calculating the weight of evidence provided by X-chromosomal analysis. Finally, we investigated the risk of erroneous decisions when using DNA in-vestigations for family reunification. We showed that the risk is increased due to uncertainties regarding population allele frequencies, consanguinity and compet-ing close relationship between the tested individuals. Additional information and the use of a refined model for the alternative hypotheses reduced the risk of making erroneous decisions. In summary, as a result of the work on this thesis, we can use mitochondrial DNA and X-chromosome markers in order to resolve complex relationship in-vestigations. Moreover, the reliability of likelihood estimates has been increased by the development of models and the study of relevant parameters affecting probability calculations.