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Neurofibromin
Neurofibromin (NF-1) is a protein that is encoded in humans, in the ''NF1'' gene. ''NF1'' is located on chromosome 17. Neurofibromin, a GTPase-activating protein that negatively regulates RAS/MAPK pathway activity by accelerating the hydrolysis of Ras-bound GTP. ''NF1'' has a high mutation rate and mutations can alter cellular growth control, and neural development, resulting in various presentations (depending on the specific allele expressed) such as Watson syndrome and neurofibromatosis type 1 (NF1, also known as von Recklinghausen syndrome). Symptoms of NF1 include disfiguring cutaneous neurofibromas (CNF), café au lait pigment spots, plexiform neurofibromas (PN), skeletal defects, optic nerve gliomas, life-threatening malignant peripheral nerve sheath tumors (MPNST), pheochromocytoma, attention deficits, learning deficits and other cognitive disabilities. Gene ''NF1'' was cloned in 1990 and its product neurofibromin was identified in 1992. Neurofibromin, a GTPase- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plexiform Neurofibroma
A neurofibroma is a benign nerve-sheath tumor in the peripheral nervous system. In 90% of cases, they are found as stand-alone tumors (solitary neurofibroma, solitary nerve sheath tumor or sporadic neurofibroma), while the remainder are found in persons with neurofibromatosis type I (NF1), an autosomal-dominant genetically inherited disease. They can result in a range of symptoms from physical disfiguration and pain to cognitive disability. Neurofibromas arise from nonmyelinating-type Schwann cells that exhibit biallelic inactivation of the ''NF1'' gene that codes for the protein neurofibromin. This protein is responsible for regulating the RAS-mediated cell growth signaling pathway. In contrast to schwannomas, another type of tumor arising from Schwann cells, neurofibromas incorporate many additional types of cells and structural elements in addition to Schwann cells, making it difficult to identify and understand all the mechanisms through which they originate and develop. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurofibromatosis Type I
Neurofibromatosis type I (NF-1), or von Recklinghausen syndrome, is a complex multi-system neurocutaneous disorder caused by a subset of genetic mutations at the neurofibromin 1 (''NF1'') locus. Other conditions associated with mutation of the ''NF1'' gene include Watson syndrome. NF-1 is a gene on chromosome 17 that is responsible for production of a protein (neurofibromin) which is needed for normal function in many human cell types. causes tumors along the nervous system that can grow anywhere on the body. is one of the most common genetic disorders and is not limited to any person's race or sex. NF-1 is an autosomal dominant disorder, which means that mutation or deletion of one copy (or allele) of the is sufficient for the development of , although presentation varies widely and is often different even between relatives affected by . , there are at least 100,000 people in the U.S. and about 25,000 people in the UK who have been diagnosed with NF. Common symptoms of inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pheochromocytoma
Pheochromocytoma is a rare tumor of the adrenal medulla composed of chromaffin cells and is part of the paraganglioma (PGL) family of tumors, being defined as an intra-adrenal PGL. These neuroendocrine tumors can be sympathetic, where they release catecholamines into the bloodstream which cause the most common symptoms, including hypertension (high blood pressure), tachycardia (fast heart rate), sweating, and headaches. Some PGLs may secrete little to no catecholamines, or only secrete paroxysmally (episodically), and other than secretions, PGLs can still become clinically relevant through other secretions or mass effect (most common with head and neck PGL). PGLs of the head and neck are typically parasympathetic and their sympathetic counterparts are predominantly located in the abdomen and pelvis, particularly concentrated at the organ of Zuckerkandl at the bifurcation of the aorta. Signs and symptoms The symptoms of a sympathetic pheochromocytoma are related to sympathetic n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ras GTPase
Ras, from "Rat sarcoma virus", is a family of related proteins that are expressed in all animal cell lineages and organs. All Ras protein family members belong to a class of protein called small GTPase, and are involved in transmitting signals within cells ( cellular signal transduction). Ras is the prototypical member of the Ras superfamily of proteins, which are all related in three-dimensional structure and regulate diverse cell behaviours. When Ras is 'switched on' by incoming signals, it subsequently switches on other proteins, which ultimately turn on genes involved in cell growth, differentiation, and survival. Mutations in Ras genes can lead to the production of permanently activated Ras proteins, which can cause unintended and overactive signaling inside the cell, even in the absence of incoming signals. Because these signals result in cell growth and division, overactive Ras signaling can ultimately lead to cancer. The three Ras genes in humans (''HRAS'', ''KRAS'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome 17 (human)
Chromosome 17 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 17 spans more than 84 million base pairs (the building material of DNA) and represents between 2.5 and 3% of the total DNA in cells. Chromosome 17 contains the Homeobox B gene cluster. Genes Number of genes The following are some of the gene count estimates of human chromosome 17. Because researchers use different approaches to genome annotation their predictions of the number of genes on each chromosome varies (for technical details, see gene prediction). The most conservative estimate, from CCDS, represents a lower bound on the total number of human protein-coding genes. Gene list The following is a partial list of genes on human chromosome 17. For complete list, see the link in the infobox on the right. The following are some of the genes and their corresponding Cytogenetic location on chromosome 17: p-arm q-arm Diseases and disord ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Watson Syndrome
Watson syndrome is a rare genetic condition characterised by café-au-lait patches of skin, short stature, pulmonary stenosis, developmental delays, and learning difficulties. Its inheritance is autosomal dominant, and it may also occur with Lisch nodules of the ocular iris, axillary/inguinal freckling, and neurofibromas. Watson syndrome is caused by mutations in the ''NF1'' gene, the same gene associated with neurofibromatosis type 1. It is believed that Watson syndrome and neurofibromatosis-1 result from allelic mutations at the ''NF1'' locus''.'' Watson syndrome has sometimes been described as a 'milder form' of neurofibromatosis-1 due to shared features including mutation of the ''NF1'' gene, café-au-lait patches, and neurofibroma, variably presenting with similar cognitive and physiological features to Noonan syndrome, a genetic condition resulting in developmental delays, learning disability, cardiovascular abnormalities, and short stature. The pathophysiology of all thr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exon
An exon is any part of a gene that will form a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. The term ''exon'' refers to both the DNA sequence within a gene and to the corresponding sequence in RNA transcripts. In RNA splicing, introns are removed and exons are covalently joined to one another as part of generating the mature RNA. Just as the entire set of genes for a species constitutes the genome, the entire set of exons constitutes the exome. History The term ''exon'' is a shortening of the phrase ''expressed region'' and was coined by American biochemist Walter Gilbert in 1978: "The notion of the cistron... must be replaced by that of a transcription unit containing regions which will be lost from the mature messengerwhich I suggest we call introns (for intragenic regions)alternating with regions which will be expressedexons." This definition was originally made for protein-coding transcripts that are spliced before b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cognitive Disabilities
There are a variety of disabilities affecting cognitive ability. This is a broad concept encompassing various Intellectual disability, intellectual or cognitive deficits, including intellectual disability (formerly called ''mental retardation''), deficits too mild to properly qualify as intellectual disability, various specific conditions (such as specific learning disability), and problems acquired later in life through acquired brain injuries or neurodegenerative diseases like dementia. Many of these disabilities have an effect on memory, which is the ability to Recall (memory), recall what has been learned over time. Typically memory is moved from sensory memory to working memory, and then finally into long-term memory. People with cognitive disabilities typically will have trouble with one of these types of memory. Intellectual disability Intellectual disability, also known as ''general learning disability'', and previously known as ''mental retardation'' (a term now consid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alternative Splicing
Alternative splicing, alternative RNA splicing, or differential splicing, is an alternative RNA splicing, splicing process during gene expression that allows a single gene to produce different splice variants. For example, some exons of a gene may be included within or excluded from the final RNA product of the gene. This means the exons are joined in different combinations, leading to different splice variants. In the case of protein-coding genes, the proteins translated from these splice variants may contain differences in their amino acid sequence and in their biological functions (see Figure). Biologically relevant alternative splicing occurs as a normal phenomenon in eukaryotes, where it increases the number of proteins that can be encoded by the genome. In humans, it is widely believed that ~95% of multi-exonic genes are alternatively spliced to produce functional alternative products from the same gene but many scientists believe that most of the observed splice variants ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genomic DNA
Genomic deoxyribonucleic acid (abbreviated as gDNA) is chromosomal DNA, in contrast to extra-chromosomal DNAs like plasmids. Most organisms have the same genomic DNA in every cell; however, only certain genes are active in each cell to allow for cell function and differentiation within the body. gDNA predominantly resides in the cell nucleus packed into dense chromosome structures. Chromatin refers to the combination of DNA and proteins that make up chromosomes. When a cell is not dividing, chromosomes exist as loosely packed chromatin mesh. The genome of an organism (encoded by the genomic DNA) is the (biological) information of heredity which is passed from one generation of organism to the next. That genome is transcribed to produce various RNAs, which are necessary for the function of the organism. Precursor mRNA (pre-mRNA) is transcribed by RNA polymerase II in the nucleus. pre-mRNA is then processed by splicing to remove introns, leaving the exons in the mature messenger ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genomic Sequence
A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as regulatory sequences (see non-coding DNA), and often a substantial fraction of junk DNA with no evident function. Almost all eukaryotes have mitochondria and a small mitochondrial genome. Algae and plants also contain chloroplasts with a chloroplast genome. The study of the genome is called genomics. The genomes of many organisms have been sequenced and various regions have been annotated. The first genome to be sequenced was that of the virus φX174 in 1977; the first genome sequence of a prokaryote (''Haemophilus influenzae'') was published in 1995; the yeast (''Saccharomyces cerevisiae'') genome was the first eukaryotic genome to be sequenced in 1996. The Human Genome Project was started in October 1990, and the first draft sequences ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
