Developmental language impairments are neurodevelopmental disorders in which the acquisition of language, a task which children typically perform with ease, is hindered or fraught with difficulty. This work focuses on specific language impairment (SLI), a common and highly heritable language impairment in which language development is abnormal while other developmental domains are normal. Additionally, a case-study of a child with a broader linguistic and behavioural phenotype is also presented. The work described in this thesis includes both genetic and functional investigations which were aimed at identifying candidate genes for language impairment and provide insight into the genetic mechanisms that underlie language development. I performed a genome-wide association study of SLI which included child genotype effects, maternal genotype effects, parent-of-origin effects, and maternal-foetal interaction effects. This study found significant paternal parent-of-origin effects with the gene NOP9 on chromosome 14, and suggestive maternal parent-of-origin effects with a region on chromosome 5 which had previously been implicated in autism and ADHD. Case-control and quantitative association analyses of HLA genes and SLI identified several risk alleles and protective alleles. A case-control association analysis for related individuals which used an isolated population affected by SLI identified a non-synonymous coding variant in the gene NFXL1 which was significantly more frequent in affected individuals than in unaffected individuals. High-throughput sequencing of the coding regions of NFXL1 and LD blocks surrounding associated variants in ATP2C2, CMIP and CNTNAP2 (as reported in previous studies) identified novel or rare non-synonymous coding variants in NFXL1 and ATP2C2 in SLI families as well as intronic variants in all four genes that were significantly more frequent in SLI probands than in population controls. I describe a functional study of NFXL1 examining its expression in various brain regions, the presence of different splice variants across several tissues, its effect on genes it potentially interacts with, and the subcellular localisation of the protein. Finally, I present the case-study of a child with language impairment who had chromosomal rearrangements which spanned the location of FOXP2. I examine the potential influence the chromosomal rearrangements had on FOXP2 expression and describe a lincRNA gene which was disrupted by the chromosomal inversion. In conclusion, this work identified new candidate genes for language impairment, provided further support for the involvement of previously-identified candidate genes in SLI and contributed to the understanding of the molecular function of a newly-identified candidate gene for SLI.

It has been demonstrated that retinal photoreception among mammals extends beyond rods and cones to include a small number of intrinsically photosensitive retinal ganglion cells (pRGCs), which are capable of responding to light due to expression of the melanopsin (OPN4) photopigment. OPN4 may have therapeutic potential if ectopically expressed in the degenerate retina in cases where photoreceptors are lost, but the other molecules involved in this light induced transduction cascade are less well characterized. Therefore I sought to probe further the mechanism of OPN4 mediated light sensitivity by siRNA mediated knock down of specific molecules in two mice models in which complete loss of rods and cones renders them almost exclusively dependent on the OPN4 pathway for light sensitivity. I generated siRNA probes against the long transcript variant of murine Opn4 mRNA and first tested these probes on the murine Neuro2A (N2a) cell line, before assessing effects in C3H/HeN rd and rodless/coneless rd/rd cl mice. siRNA was injected intravitreally into one eye and pupillometry was assessed, combined with molecular analyses at various timepoints. Reverse transcription polymerase chain reaction (RT-PCR) analysis in N2a cells confirmed Opn4 knockdown and immunolabelling techniques identified >85% silencing with siRNA. Pupil responses in the rd and rd/rd cl mice were inhibited by the siRNA injections in vivo which confirmed the functional effect of Opn4 silencing detected by molecular analysis. I therefore present a novel reproducible in vivo model in which siRNA induced silencing of the melanopsin pathway can be assessed by pupillometry and compared to levels of mRNA and protein at specific timepoints. Probes against other putative candidate genes, such as TRPC3, may unravel the molecular interactions of this pathway. This may help in future to induce light sensitivity in other retinal neurons in patients who are completely blind from photoreceptor loss.

Next-generation sequencing methods now allow rapid and cost-effective sequencing of DNA on a scale not previously possible. This offers great opportunities for the research of Mendelian disorders, but also significant challenges. The sequencing of exomes, or whole genomes, has emerged as a powerful clinical research tool, with targeted gene analyses generally being preferred in the clinical diagnostic setting. These methods have been employed here with the aim of identifying novel genetic causes of inherited heart disorders and to gain insights into the utility and limitations of these techniques for clinical diagnosis in these disorders. Data produced from the introduction of a targeted multi-gene next-generation sequencing test into clinical practice has been studied. Variation within the mitochondrial genome has been analysed to assess the importance of mitochondrial DNA variants in patients with hypertrophic cardiomyopathy. The m.4300A>G mutation is identified as an important cause of this disorder, with other previously cardiomyopathy-associated and novel variants also identified. Such multi-gene tests can facilitate interpretable and phenotype-relevant results, but at the expense of limiting more extensive data acquisition. Whole-genome sequencing has been performed in five families with different autosomal dominant inherited heart disease phenotypes of unknown genetic aetiology. In two of these likely pathogenic variants were identified, one in the gene encoding titin (TTN) and the other in the calcium channel subunit gene CACNA1C. In vitro studies were undertaken to support the pathogenicity of the TTN variant and understand the functional effects of this. In the other three families either multiple candidate gene variants were identified or no clear candidate variant was identified. This highlights the difficulties in interpreting these results, even in carefully selected families. Overall, although the research benefits of exome or genome studies are evident, the interpretation and validation of genetic variant data produced remains highly challenging for clinical diagnosis.

Common mycobacterial diseases, including tuberculosis and leprosy, contribute to major mortality and morbidity worldwide. Despite evidence of an important role of host genetic factors in susceptibility to these infections, few compelling genetic associations have been identified with previous candidate gene and linkage approaches. This thesis investigates the genetic factors of human immunity to these mycobacterial diseases using a high-throughput approach of association testing. To assess genetic susceptibility to tuberculosis, I have conducted a genome-wide association study in the Gambian population as part of the Wellcome Trust Case Control Consortium (WTCCC). The study reveals the region flanking CADM1 as a potential susceptibility locus. Combining this study with a Ghanaian cohort further implicates two genetic loci at chromosome 18q11.2 (P = 9.2x10⁻⁹) and PARD3B (P = 1.4x10⁻⁶). For leprosy, I have performed a gene-centric association study in the New Delhi Indian population. Evidence of significant association was observed in the HLA-DRB1/DQA1 (P = 4.9x10⁻¹⁴) and TLR1 (P = 1.7x10⁻⁹) loci. These studies identify important genomic regions that may be involved in immunity to tuberculosis and leprosy. Further analysis revealed a significant immunogenetic overlap between tuberculosis and leprosy. This provides proof-of-principle for the subsequent aggregate analysis for mycobacterial susceptibility, which suggests that the steroid biosynthesis pathway may be important in anti-mycobacterial immunity. This thesis represents one of the largest studies to identify the genetic factors for human immunity against mycobacteria. These novel findings will further enhance vaccine and pharmaceutical efforts into prevention and treatment of these mycobacterial diseases.

<p><b>Purpose.</b> The main aim of the present study was to evaluate the effect of a low fat, low lactose diet on acute and late gastrointestinal side effects of pelvic radiotherapy. We also wanted to evaluate if such a treatment would influence the patients health related quality of life (HRQOL) in any way.</p><p><b>Background</b>. Cancer therapies and their side effects may cause nutritional problems and malnutrition. Pelvic radiotherapy, a common treatment modality for patients with carcinoma of the endometrium or cervix, is associated with both acute and late side effects that may affect nutritional status. Acute injury may lead to impaired absorption of nutrients and fluid. The patients experience diarrhoea, weight loss, nausea and vomiting. Bile salt malabsorption may be a factor in the pathogenesis of the diarrhoea. In cases of bile salt malabsorption a low fat diet will cause decreased bile salt excretion and thereby relief of symptoms. This assumption was evaluated in a small, non-randomised study in 1985. The results indicated that a low fat diet may reduce the frequency of diarrhoea and use of anti-diarrhoeal agents during radiotherapy. These findings were regarded as promising and since nutrition management guidelines for radiation enteritis were lacking in the literature, a clinical trial was planned.</p><p><b>Methods</b>. The study was designed as an open randomised clinical trial and conducted at the Norwegian Radium Hospital (NRH). The intervention diet (low fat, low lactose) was to be followed during and six weeks after radiotherapy. Measurements were performed at basement, the 3rd and last week of radiotherapy, six week after and then every 8th week. The entire period was one year. In November 1993 the surviving patients were approached again and asked to complete a questionnaire package similar to the one completed during the clinical trial. The study population was recruited from the department of gynaecology at NRH. The main selection criteria were pelvic radiotherapy (dose above 40 Gy) age = 75 years and a WHO functional status = 2. Patients were consecutive included from May 1988 through May 1990 and 143 women were included. Seventy-one were assigned to the intervention diet and 72 to the control group. In November 1993, 94 women were alive without any known relapse and 79 (84%) accepted participation. The women registered use of Loperamid and the daily number and consistency of bowel movements. The data on bowel movements was categorised and used to evaluate if diarrhoea was present or not. Nutritional status was evaluated by the means of weight development, arm muscle circumference (AMC), serum transferring (STF) and serum albumin (s-Alb). Dietary intake was assessed by 48-hour recall prior to radiotherapy, 4-days unweighed dietary record during radiotherapy and 7-days weighed dietary records during follow-up. 24-hour urinary nitrogen was used to validate the food records. HRQOL was defined as the patients' self-reported subjective physical and psychosocial situation as a consequence of disease and treatment. It was measured with the EORTC Core Quality of Life Questionnaire 36-item version (EORTC QLQ-C36).</p><p><b>Results</b>. During the last week of radiotherapy 14 patients (23%) in the intervention group and 32 (48%) in the control group reported diarrhoea (p< 0.01). The intervention group also used less anti-diarrhoea medication than the control group, 0.6 tablets per day versus 1.1 (p<0.01). Six weeks after end of radiotherapy, no group differences were found with regard to bowel movements or medication. The intervention group had a lower energy intake than the control group during radiotherapy, 5.7 MJ versus 6.5 MJ (p<0.05). The mean daily fat intake was respectively 34.3 g and 60.1 g (p<0.001). The intervention group received a significant lower part of the energy from milk products, meats, fats and sugar than the control group, and consumed more energy from vegetables and fruits, cereals and fish. Weight loss was more pronounced in the intervention group (mean reduction of 2.6 kg versus 1.7 kg) than in the control group (ns) during treatment. Mean values of AMC, s-Alb and STF were within the reference range in both groups during the entire observation period. During the last week of radiotherapy six patients (9%) in the intervention group and 4 (6%) in the control group were mildly depleted (ns). At 12 weeks and after one year none of the patients could be categorised as malnourished. No major differences in HRQOL were found between the two groups during radiotherapy and one-year follow up. Within the control group an association between diarrhoea and deteriorated role functioning, physical functioning and fatigue was found during the last week of radiotherapy that was not found in the intervention group. Regarding late effects of radiotherapy (3-4 years after radiotherapy) both groups had more diarrhoea than in the general population, 23.8 versus 9.5 (p<0.01). There was however a tendency to more pronounced diarrhoea in the control group (29.6 (SD=27.3)) than in the intervention group (19.4 (SD=25.4)) though not statistical significant. Substantial diarrhoea was associated deteriorated SF and fatigue. </p><p><b>Conclusions</b>. The intervention group had less diarrhoea and used less Loperamide during radiotherapy than the control group. This finding did not affect nutritional status since no differences in nutritional status were found between the two groups. Both groups had a reduced energy intake and weight loss during radiotherapy. In the control group diarrhoea increased fatigue and had negative effects on physical functioning and role functioning. The intervention did not lead to differences in late radiation injury and chronic diarrhoea 3-4 years after treatment but diarrhoea was most prominent in the control group. Diarrhoea as a late effect increased fatigue and had a negative influence on social well being.</p>

<p>The onset of cigarette smoking begins primarily in adolescence, and prevalence of smoking among adolescents has been increased during the last ten years. The prevalence of adolescent smoking increases with age and is more common or at least as common in girls as in boys in most western countries.</p><p>Until recently the intensive investigation on health effects of smoking has been mostly conducted among adults. In adolescence the long-term health consequences have been reviewed, but current health problems are probably more important to adolescents and may be more motivating for smoking prevention and cessation. Increased morbidity among adolescent smokers has been reported, but specific current health problems and medication use have received little attention. More</p><p>Control of smoking is a primary health goal. An underlying premise for promotion of physical activity in adolescence is that it may mead to a healthy lifestyle persisting through adulthood. Encouraging participation in sports has been recommended as smoking prevention and as part of smoking cessation programs. Smoking habits within different types of sports has received less attention, and whether physical activity has an impact on lung function is debated.</p><p>Adolescent smokers are often unsuccessful in quitting and difficult to recruit and retain in smoking cessation programs. Occasional smoking may be the strongest risk factor for daily smoking, but occasional smokers could be an important target group for smoking cessation who could be discouraged from moving into daily smoking status. </p><p>The first aim of this thesis was to study associations between smoking and current health status by examining associations between daily smoking and subjective health problems (Paper 1), and gender specific effects on respiratory symptoms and lung function (Paper II). The associations between physical activity and lung function in never smokers and daily smokers were also assessed (Paper III). The second aim was to study factors that might be useful in smoking</p>

<p>Preeclampsia is a complex and variable maternal disturbance that ranges from a dramatic onset at early gestation to slowly developing symptoms towards term. Hypertension and renal involvement with proteinuria are cardinal signs, which are often accompanied by fluid retention, blood-clotting dysfunction, and reduced organ perfusion. HELLP (haemolysis, elevated liver enzymes, and low platelet count) syndrome is regarded as a variant of preeclampsia, and the fulminante disease, eclampsia, includes convulsions. Preeclampsia is the main cause of maternal and fetal morbidity and mortality in western countries (1, 2), and in Nordic countries, 17 percent of maternal deaths have been ascribed to preeclampsia (2). Antenatal care in Norway includes on average 12 doctor/midwife consultations per pregnancy (3), and since blood pressure monitoring and urinary testing are main aims of the consultations, preeclampsia is a pregnancy complication that also generates substantial societal costs.</p> / Paper II, III, IV and V reproduced with permission of Elsevier, sciencedirect.com

<p>Stroke is the third leading cause of death and the major course of long-term disabilities in industrialized countries. Most surviving stroke patients show some degree of spontaneous recovery, but persistent symptoms in sensorimotor and cognitive functions are common. The symptoms can be reproduced in experimental stroke models in rats by occlusion of the middle cerebral artery. Housing rats in an enriched environment (EE), i.e. group housing in a large cage with toys that are changed daily, increases neuronal plasticity in healthy rats and can also improve functional recovery after experimental stroke. </p><p> The present thesis investigates the effect of EE on the recovery of sensorimotor and cognitive functions one month after focal cerebral ischemia in rats, with emphasis on the underlying molecular mechanisms. Furthermore, EE-induced effect on gene expression in healthy rats was investigated after different periods of EE-housing and at different time points of the day. </p><p> We show an improved recovery of both sensorimotor and cognitive functions in rats housed in EE for one month after focal cerebral ischemia. The recovery of sensorimotor function correlated significantly to mRNA expression of the plasticity associated transcription factors NGFI-A and NGFI-B in hippocampus and cortical regions outside the infarct. Social interaction seems to be an important component for the beneficial effects of EE after focal cerebral ischemia. Microarray analysis of hippocampal gene expression after one month of postischemic environmental enrichment revealed no confirmable EE-induced changes that could explain the improved recovery in spatial memory. Interestingly, healthy rats housed in EE showed increased mRNA expression of NGFI-A and Krox-20 exclusively during the dark period of the day compared to rats housed in isolation. In addition, EE housed rats had a substantial diurnal variation in NGFI-A, Krox-20 and NGFI-B mRNA expression; this was absent in single-housed rats. EE-induced changes in gene expression are more evident during the dark period of the day, when rats are more active and can benefit from the stimulating environment. This is important to consider in future investigation of putative mediators of the EE-induced neuronal plasticity. </p><p> In summary, these findings may contribute to an increased understanding of the underlying molecular mechanisms behind improved functional recovery in rats housed in enriched environment after focal cerebral ischemia.</p>

<p>In multicellular organisms all cells in one individual have an identical genotype, and yet their bodies consist of many and very different tissues and thus many different cell types. Somehow there must be a difference in how genes are interpreted. So, there must be signals that tell the genes when and where to be active and inactive, respectively. In some instances a specific an expression pattern (active or inactive) is epigenetic; it is established and maintained throughout multiple rounds of cell divisions. In the developing <i>Drosophila</i> embryo, the proper expression pattern of e.g. the homeotic genes <i>Abd-B</i> and <i>Ubx</i> is to be kept active in the posterior part and silenced in the anterior. Properly silenced homeotic genes are crucial for the correct segmentation pattern of the fly and the Polycomb group (Pc-G) proteins are vital for maintaining this type of stable repression.</p><p>As part of this thesis, <i>Suppressor of zeste 12 (Su(z)12)</i> is characterized as a <i>Drosophila</i> Pc-G gene. Mutations in the gene cause widespread misexpression of several homeotic genes in embryos and larvae. Results show that the silencing of the homeotic genes <i>Abd-B</i> and <i>Ubx</i>, probably is mediated via physical binding of SU(Z)12 to Polycomb Response Elements in the BX-C. <i>Su(z)12</i> mutations are strong suppressors of position-effect-variegation and the SU(Z)12 protein binds weakly to the heterochromatic centromeric region. These results indicate that SU(Z)12 has a function in heterochromatin-mediated repression, which is an unusual feature for a Pc-G protein. The structure of the <i>Su(z)12</i> gene was determined and the deduced protein contains a C2-H2 zinc finger domain, several nuclear localization signals, and a region, the VEFS box, with high homology to mammalian and plant homologues. <i>Su(z)12 </i>was originally isolated in a screen for modifiers of the zeste-white interaction and I present results that suggests that this effect is mediated through an interaction between <i>Su(z)12 </i>and <i>zeste</i>. I also show that <i>Su(z)12</i> interact genetically with other Pc-G mutants and that the SU(Z)12 protein binds more than 100 euchromatic bands on polytene chromosomes. I also present results showing that SU(Z)12 is a subunit of two different E(Z)/ESC embryonic silencing complexes, one 1MDa and one 600 kDa complex, where the larger complex also contains PCL and RPD3. </p><p>In conclusion, results presented in this thesis show that the recently identified Pc-G gene, <i>Su(z)12</i>, is of vital importance for correct maintenance of silencing of the developmentally important homeotic genes.</p>

<p>Predisposition to autoimmune diseases such as, rheumatoid arthritis, diabetes, and multiple sclerosis, is caused by the effect of multiple genes and a strong influence from the environment. </p><p>In this study, I have investigated genetic factors that confer susceptibility to rheumatoid arthritis in a rat model. This work has led to the identification of several chromosomal regions, containing uncharacterized genes that directly or indirectly are associated to the arthritis development in these rats. We have observed that timing, gender, and genetic interactions are features that play a part in the effect that these genetic factors exert. </p><p>Unarguably, animal models for human disorders display differences to the human form of disease. An important fact is however that the same chromosomal regions are identified in both rodent and human studies, which suggests that there are genetic factors that we have in common, which are involved directly or indirectly with an autoimmune response. </p><p>Focusing the interest on these similarities, and on the possibility to apply a wide set of genetic tools, make animal models an invaluable, and probably necessary, instrument to dissect the genetic component of complex disorders. To fully comprehend the genetic basis for a complex disorder like this, will require understanding of how multiple genes interact with each other to cause disease. </p><p>We have been able to demonstrate that chronic arthritis, in a rat model for rheumatoid arthritis, is regulated by several genes and that these act during different temporal phases of the disease. These findings will hopefully contribute to our understanding of the etiology and progression of rheumatoid arthritis.</p>