Whole-genome association studies of sporadic amyotrophic lateral sclerosis: are retroelements involved?

Biological significance of RNA editing in cells

RNA editing is one of the post-transcriptional RNA processes. RNA editing generates RNA and protein diversity in eukaryotes and results in specific amino acid substitutions, deletions, and changes in gene expression levels. Adenosine-to-inosine RNA editing represents the most important class of editing in human and affects function of many genes. The importance of balancing RNA modification levels across time and space is becoming increasingly evident. In this review, we overview the biological significance of RNA editing including RNA editing in tumorigenesis, RNA editing in neuronal tissues, RNA editing as a regulator of gene expression, and RNA editing in dsRNA-mediated gene silencing, which may increase our understanding of RNA biology.

Intramedullary spinal cord implantation of human CD34+ umbilical cord-derived cells in ALS

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder with marginal therapeutic options. Degeneration of motor neurons in the primary motor cortex, brainstem and spinal cord lead to rapidly progressive paralysis and finally to death due to respiratory failure. As pharmacological therapies have failed to provide sufficient neuroprotective effects in ALS, transplantation of stem or progenitor cells is considered a promising treatment strategy. Cell transplantation approaches in ALS mainly aim to generate a neuroprotective environment for degenerating motor neurons by transplantation of non-neuronal cells, rather than to replace lost motor neurons. We present a 63-year-old male patient suffering from ALS who underwent intramedullary thoracic spinal cord implantation of human CD34(+) umbilical cord-derived haematopoietic progenitor cells with a three-year follow up after transplantation.

Genomic medicine and neurological disease

"Genomic medicine" refers to the diagnosis, optimized management, and treatment of disease--as well as screening, counseling, and disease gene identification--in the context of information provided by an individual patient's personal genome. Genomic medicine, to some extent synonymous with "personalized medicine," has been made possible by recent advances in genome technologies. Genomic medicine represents a new approach to health care and disease management that attempts to optimize the care of a patient based upon information gleaned from his or her personal genome sequence. In this review, we describe recent progress in genomic medicine as it relates to neurological disease. Many neurological disorders either segregate as Mendelian phenotypes or occur sporadically in association with a new mutation in a single gene. Heritability also contributes to other neurological conditions that appear to exhibit more complex genetics. In addition to discussing current knowledge in this field, we offer suggestions for maximizing the utility of genomic information in clinical practice as the field of genomic medicine unfolds.

Effect of genetic background on phenotype variability in transgenic mouse models of amyotrophic lateral sclerosis: a window of opportunity in the search for genetic modifiers

Transgenic (Tg) mouse models of FALS containing mutant human SOD1 genes (G37R, G85R, D90A, or G93A missense mutations or truncated SOD1) exhibit progressive neurodegeneration of the motor system that bears a striking resemblance to ALS, both clinically and pathologically. The most utilized and best characterized Tg mice are the G93A mutant hSOD1 (Tg(hSOD1-G93A)1GUR mice), abbreviated G93A. In this review we highlight what is known about background-dependent differences in disease phenotype in transgenic mice that carry mutated human or mouse SOD1. Expression of G93A-hSOD1Tg in congenic lines with ALR, NOD.Rag1KO, SJL or C3H backgrounds show a more severe phenotype than in the mixed (B6xSJL) hSOD1Tg mice, whereas a milder phenotype is observed in B6, B10, BALB/c and DBA inbred lines. We hypothesize that the background differences are due to disease-modifying genes. Identification of modifier genes can highlight intracellular pathways already suspected to be involved in motor neuron degeneration; it may also point to new pathways and processes that have not yet been considered. Most importantly, identified modifier genes provide new targets for the development of therapies.

Neurodegenerative diseases: Lessons from genome-wide screens in small model organisms

Various age-related neurodegenerative diseases, including Parkinson's disease, polyglutamine expansion diseases and Alzheimer's disease, are associated with the accumulation of misfolded proteins in aggregates in the brain. How and why these proteins form aggregates and cause disease is still poorly understood. Small model organisms—the baker's yeast Saccharomyces cerevisiae, the nematode worm Caenorhabditis elegans and the fruit fly Drosophila melanogaster—have been used to model these diseases and high-throughput genetic screens using these models have led to the identification of a large number of genes that modify aggregation and toxicity of the disease proteins. In this review, we revisit these models and provide a comprehensive comparison of the genetic screens performed so far. Our integrative analysis highlights alterations of a wide variety of basic cellular processes. Not all disease proteins are influenced by alterations in the same cellular processes and despite the unifying theme of protein misfolding and aggregation, the pathology of each of the age-related misfolding disorders can be induced or influenced by a disease-protein-specific subset of molecular processes.