Progranulin is the precursor of granulins, and its downregulation may lead to neurodegeneration. The single-nucleotide polymorphism rs5848 increases the risk of Alzheimer's disease (AD). We explored the association between alleles of rs5848 and the risk of AD in the Taiwanese population. The frequency of the homozygous TT genotype (16.4 vs. 10.0%) increased in AD subjects by an odds ratio (OR) of 1.87 (p = 0.03) corrected for APOE ε4, age and gender. Interaction between age and homozygous TT genotype accentuated the risk of AD (OR 4.44, p < 0.001). The homozygous TT genotype of rs5848 may play a role in the genetic risk of AD development, especially in the elderly.
"Although this genetic association could not be replicated in two series of largely clinical FTLD patients [46,47], these results are consistent with PGRN loss as the disease mechanism associated with FTLD-TDP. SNP rs5848 was also reported as a genetic risk factor for the development of hippocampal sclerosis in older people and for the development of Alzheimer's disease in a Taiwanese population [48,49]. Genetic association studies using several other common polymorphisms in the GRN genomic region further identified significant association of GRN variants in Belgian and Finnish Alzheimer's disease populations [40,50], in Belgian and Dutch ALS populations , and in an Italian FTLD population . "
[Show abstract][Hide abstract] ABSTRACT: Frontotemporal lobar degeneration (FTLD) is a devastating neurodegenerative disease that is the second most common form of dementia affecting individuals under age 65. The most common pathological subtype, FTLD with transactive response DNA-binding protein with a molecular weight of 43 kDa inclusions (FTLD-TDP), is often caused by autosomal dominant mutations in the progranulin gene (GRN) encoding the progranulin protein (PGRN). GRN pathogenic mutations result in haploinsufficiency, usually by nonsense-mediated decay of the mRNA. Since the discovery of these mutations in 2006, several groups have published data and animal models that provide further insight into the genetic and functional relevance of PGRN in the context of FTLD-TDP. These studies were critical in initiating our understanding of the role of PGRN in neural development, degeneration, synaptic transmission, cell signaling, and behavior. Furthermore, recent publications have now identified the receptors for PGRN, which will hopefully lead to additional therapeutic targets. Additionally, drug screens have been conducted to identify pharmacological regulators of PGRN levels to be used as potential treatments for PGRN haploinsufficiency. Here we review recent literature describing relevant data on GRN genetics, cell culture experiments describing the potential role and regulators of PGRN in the central nervous system, animal models of PGRN deficiency, and potential PGRN-related FTLD therapies that are currently underway. The present review aims to underscore the necessity of further elucidation of PGRN biology in FTLD-related neurodegeneration.
Alzheimer's Research and Therapy 01/2012; 4(1):4. DOI:10.1186/alzrt102 · 3.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Frontotemporal dementia (FTD) is a clinical syndrome with a heterogeneous molecular basis. Until recently, the underlying cause was known in only a minority of cases that were associated with abnormalities of the tau protein or gene. In 2006, however, mutations in the progranulin gene were discovered as another important cause of familial FTD. That same year, TAR DNA-binding protein 43 (TDP-43) was identified as the pathological protein in the most common subtypes of FTD and amyotrophic lateral sclerosis (ALS). Since then, substantial efforts have been made to understand the functions and regulation of progranulin and TDP-43, as well as their roles in neurodegeneration. More recently, other DNA/RNA binding proteins (FET family proteins) have been identified as the pathological proteins in most of the remaining cases of FTD. In 2011, abnormal expansion of a hexanucleotide repeat in the gene C9orf72 was found to be the most common genetic cause of both FTD and ALS. All common FTD-causing genes have seemingly now been discovered and the main pathological proteins identified. In this Review, we highlight recent advances in understanding the molecular aspects of FTD, which will provide the basis for improved patient care through the development of more-targeted diagnostic tests and therapies.
[Show abstract][Hide abstract] ABSTRACT: Genetic variants in the granulin (GRN) gene have been shown to increase the risk of Alzheimer's disease (AD). Here, we report that the A allele of rs5848 in GRN reduces plasma granulin levels in a dose-dependent manner in a clinically-defined AD sample cohort. Similarly, the mRNA levels of granulin were decreased with respect to A allele of rs5848 in the inferior temporal cortex of neuropathologically confirmed AD patients. Our findings suggest that the A allele of rs5848 is functionally relevant by reducing the expression of granulin.
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