Ph.D. Theses
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Browsing Ph.D. Theses by Subject "Amyotrophic lateral sclerosis."
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Item Amyotrphic lateral sclerosis in Turkey : Studies on Familial and sporadic ALS using high-throughput genomic technologies(Thesis (Ph.D.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2010., 2010.) Özoğuz, Aslıhan.; Başak, A. Nazlı.Amyotrophic Lateral Sclerosis (ALS) is a late-onset neurodegenerative disease, characterized by death of motor neurons in cortex, brainstem and spinal cord. It is a multifactorial disease with interacting pathogenic mechanisms. Most incidences are sporadic (SALS), while 10 per cent of cases have a family history (FALS). The genetics of ALS is complex; eight genes and six loci with autosomal dominant (AD), autosomal recessive and X-linked patterns of inheritance have been identified thus far. In the framework of this study, 198 Turkish ALS cases were investigated for possible mutations in the SOD1 gene. Five FALS cases were shown to carry disease-causing SOD1 mutations, while six were carriers of a rare polymorphism. In the next step, AD, nonconsanguineous FALS and juvenile cases were analyzed for the TDP-43, FUS and ANG genes via DNA sequencing. One homozygous D90A case, represented as recessive, was investigated by haplotype analysis and was compared to 21 Scandinavian ALS cases in search of a common ancestry. Additionally, 15 FALS and 13 juvenile cases, who were negative for the tested genes, were analyzed by whole genome genotyping for identification of new ALS genes. While no significant regions were obtained, a recessive family was preselected for the identification of homozygosity regions. Five candidate genes located within homozosity regions were examined in one of the family member; no mutations were identified. The same individual was also assessed by whole exome resequencing. Furthermore, this study also contributed to a collaborative genome-wide association study in SALS, where 14 month-survival advantage was shown for homozygous CC allele at rs1541160 SNP in the gene coding KIFAP3. This is the most comprehensive study performed in Turkey on the molecular genetics of ALS. The high-throughput methodologies used and the findings presented in this thesis are expected to shed light to the complex pathogenesis of amyotrophic lateral sclerosis.Item The molecular landscape of ALS in Turkey: A multifaceted approach to the complex genetics of ALS(Thesis (Ph.D.)-Bogazici University. Institute for Graduate Studies in Science and Engineering, 2018., 2018.) İskender, Ceren.; Çağlayan, S. Hande.; Başak, A. Nazlı.Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease (NDD), characterized by degeneration of both upper and lower motor neurons leading to muscle wasting. With an incidence of two and a prevalence of four in 100.000/year, it is the third most common NDD after Alzheimer’s and Parkinson’s diseases. The last decade has proven that the ‘condition’ called ALS is both clinically and genetically heterogenous, and that the genetic component in 90% of the cases that are considered as sporadic, might be stronger than expected. In this thesis, we investigated the complex genetics of ALS in the ethnically heterogeneous yet inbred Turkish population. Familial ALS account for 22% of our cases (159/722) and 563 cases were classified as sporadic (78%). Consanguinity is calculated as 25% among familial and 17% in sporadic cases. Conventional screening of the most common ALS genes (C9orf72, SOD1, TARDBP and FUS) in patients with a family history of disease, explained the disease cause in only 33%, pointing towards marked locus heterogeneity within the population. C9orf72 hexanucleotide repeat expansion was further detected in 3% of ‘apparently sporadic’ patients. Application of whole exome sequencing (WES) in dominant and recessive Turkish pedigrees presenting with ALS or non-ALS motor neuron diseases (MNDs), revealed distinct rare or novel mutations in 20 out of 39 families and enabled differential diagnosis in cases with atypical ALS features. Common current themes in ALS, like oligogenic inheritance and possible genetic modifiers are addressed in families with incomplete penetrance and in C9orf72 expansion carriers. Oligogenic inheritance of known ALS genes was not prominent in the Turkish C9orf72-positive cases. Hypermethylation in the promoter region of C9orf72 was confirmed in Turkish patients, however it did not seem to modify age of onset. Finally, analyses of whole genome sequencing data of 625 Turkish ALS patients and 152 healthy controls in the framework of Project MinE showed population-specific aspects and once more substantiated the concept of low penetrance of rare ALS genes among sporadic patients.