Browsing by Subject "Populaatiogenetiikka"

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  • Pohjolan-Pirhonen, Risto (Helsingin yliopisto, 2018)
    Introduction: Parkinson’s disease is the second most common neurodegenerative disease in the Western countries with a prevalence of about 0.3% in the population. Approximately 5 to 10% of patients are estimated to have a hereditary form of the disease. In recent years, 23 gene loci have been found, in which mutations cause hereditary Parkinson’s disease. In Finland, however, only a few disease linked gene variants have been found so far. Aims and methods: To find out if there are gene variants previously found in Parkinson’s disease patients in the Finnish population, we searched variants found in literature search in a novel genetic database, SISu, which contains genetic data of over 10 000 Finns. In addition, to confirm population findings and search for new gene variants, we analyzed 47 patient cohort with a designed gene panel and also another cohort, containing 147 patients, by minisequencing one variant found in the population data. Results: We found 16 variants in five different genes in the population data. Three of them were considered pathogenic and four likely benign after our analysis. In addition, we found nine potentially disease linked variants in eight different patients. Four of the variants were novel. Discussion: Finns seem to carry only few previously described gene variants in genes linked to Parkinson’s disease. It is likely that Finns carry their own unique variants, some of which we also found in our study. Our analysis brings valuable information about the still scarce knowledge of the genetics of this disease in the Finnish population. In addition, we were able to evaluate the disease risk of many variants further by studying their occurrence in Finns. The study of novel gene variants may bring valuable new information about the pathogenic processes related to the disease; especially the location of a novel variant in PARK2 gene found in our study turned out to be crucial for one of the previously suggested disease mechanisms.
  • Niemi, Marianna (Helsingin yliopisto, 2018)
    Ancient DNA holds tremendous potential to answer multidisciplinary research covering topics in evolution and origins of species, their population genetics and migration. The data produced can also be used to date events in the history of particular species. Here, for the first time, these aspects are studied by analysing ancient and contemporary DNA samples from cattle and sheep from the north-east Baltic Sea region (NEBSR). The study is particularly focused in exploration of the genetic variation, frequency of local variants, origin of endangered native breeds and the beginning and development of animal husbandry in the northernmost latitudes of agriculture. This thesis binds the genetic, statistic and modelling results into a wide multidisciplinary context. By sampling 109 ancient specimens found in 66 archaeological sites and DNA samples from contemporary native breeds, the genetic history of NEBSR cattle and sheep was reconstructed from prehistory to the present. Ancient ancestral animal populations in NEBSR were different compared to current cattle and sheep. Maternally and paternally inherited mtDNA and Y-chromosomal markers revealed ancient lineages, which are no longer found in contemporary populations. Ancient and modern haplogroup data supported geographical mtDNA haplogroup distribution and expansion processes starting around 10000 BP (before present) from the Near Eastern domestication centre, expanding over the European continent and finally reaching NEBSR around 4500 – 3000 BP. A closer comparison to ancient and contemporaneous western Eurasian mtDNA data using phylogenetically younger lineages of mtDNA suggests dual origin for NEBSR cattle and sheep, the European mainland and Pontic Steppe in the Middle Volga region in western Russia. Bayesian reconstruction of effective population sizes supports a small initial population and slow beginning of animal husbandry in NEBSR. The burst of animal husbandry in the NEBSR was genetically dated to the Middle and Late Iron Age (400-1000 AD) in line with a similar burst of cereal cultivation as detected from fossil pollen from lake sediments. Throughout history, NEBSR domestic animal populations have been changing. Major changes in NEBSR have happened at least twice: in the Late Iron (Viking) Age (800-1200 AD), with the migration of Swedish farmers, in early Medieval Ages and again in the modern period, when the native breeds were dominated by global commercial dairy breeds. The associated changes in phenotype are demonstrated by the colour defining MC1R gene analysed from ancient and contemporary cattle. Iron Age cattle had a higher frequency for dominant black colour, while along with new Medieval cattle, more recessive red and wild-type alleles entered into NEBSR cattle populations. Cattle in NEBSR used to be multi-coloured throughout history, until reaching their current form in the 20th century. The breeding in prehistoric and early historic periods was an unfocused, culture-environmental selection, favouring genetic combinations that survive in the harsh historical environments. The beginning of a conscious improvement of populations by artificial selection of breeding animals likely dates to the Post-Medieval period, with constantly increasing skill and intensity during the modern period. The combination of first culture-environmental and later more goal-determinate selective breeding resulted in local animal types and, consequently, in native breeds currently valued for their national heritage, generally good health and high efficiency in low-input conditions.