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In the past decade a lot of progress was made in elucidating the genetic and pathologic make-up of frontotemporal lobar degeneration (FTLD), one of the leading causes of dementia. The genes known to date however are implicated in the autosomal dominant forms of the disease and leave a significant fraction (about 80%) of patients as yet unresolved. Therefore the first genome-wide association (GWA) studies were initiated in search for more common genetic variants influencing risk for FTLD. An essential step in the identification of novel genetic risk factors for complex diseases is the replication and confirmation of GWA association signals in independent study populations. The aim of this research project is to provide these invaluable replication studies using a powerful, well-documented, homogenous Flanders-Belgian study population. We recently participated in a GWA of FTLD with TDP43 pathology, the major pathological subtype of FTLD. The study uncovered common genetic variation in the gene TMEM106B as a putative risk factor for FTLD-TDP. Samples to set-up a second large scale international GWA study of patients with a clinical diagnosis of FTLD, to which we contributed 256 patients, have now been collected and results of the genome-wide genotyping are expected by the end of 2010. For this research project we plan to perform in depth follow-up studies of these two GWA studies of FTLD. Hereto we will test association of the GWA top single nucleotide polymorphisms (SNPs) in our Flanders-Belgian FTLD sample; sequence candidate genes within the associated regions, saturate the loci with SNPs and define the minimal associated risk haplotype blocks by allelic, genotypic and haplotype-based association analysis; and ultimately tend to isolate the genetic variants responsible for the risk modifying effect by genomic sequencing of the minimal associated loci. A better understanding of the genes and proteins involved in the pathogenic cascade leading to FTLD will be instrumental for the development of targeted therapeutic strategies to alleviate the suffering of these patients.
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