|
Trinucleotide Repeat Expansion
A trinucleotide repeat expansion, also known as a triplet repeat expansion, is the DNA mutation responsible for causing any type of disorder categorized as a trinucleotide repeat disorder. These are labelled in dynamical genetics as dynamic mutations. Triplet expansion is caused by slippage during DNA replication, also known as "copy choice" DNA replication. Due to the repetitive nature of the DNA sequence in these regions, 'loop out' structures may form during DNA replication while maintaining complementary base pairing between the parent strand and daughter strand being synthesized. If the loop out structure is formed from the sequence on the daughter strand this will result in an increase in the number of repeats. However, if the loop out structure is formed on the parent strand, a decrease in the number of repeats occurs. It appears that expansion of these repeats is more common than reduction. Generally, the larger the expansion the more likely they are to cause disease or i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosis, or meiosis or other types of damage to DNA (such as pyrimidine dimers caused by exposure to ultraviolet radiation), which then may undergo error-prone repair (especially microhomology-mediated end joining), cause an error during other forms of repair, or cause an error during replication ( translesion synthesis). Mutations may also result from substitution, insertion or deletion of segments of DNA due to mobile genetic elements. Mutations may or may not produce detectable changes in the observable characteristics ( phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution, cancer, and the development of the immune system, including junctional diversity. Mutati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myotonic Dystrophy
Myotonic dystrophy (DM) is a type of muscular dystrophy, a group of genetic disorders that cause progressive muscle loss and weakness. In DM, muscles are often myotonia, unable to relax after contraction. Other manifestations may include cataracts, intellectual disability and arrhythmia, heart conduction problems. In men, there may be early balding and infertility. While myotonic dystrophy can occur at any age, onset is typically in the 20s and 30s. Myotonic dystrophy is caused by a genetic mutation in one of two genes. Mutation of the ''Myotonin-protein kinase, DMPK'' gene causes myotonic dystrophy type 1 (DM1). Mutation of ''CNBP'' gene causes type 2 (DM2). DM is typically heredity, inherited, following an autosomal dominant inheritance pattern, and it generally anticipation (genetics), worsens with each generation. A type of DM1 may be apparent at birth. DM2 is generally milder. Diagnosis is confirmed by genetic testing. There is no cure. Treatments may include braces or wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Southern Blot
Southern blot is a method used for detection and quantification of a specific DNA sequence in DNA samples. This method is used in molecular biology. Briefly, purified DNA from a biological sample (such as blood or tissue) is digested with restriction enzymes, and the resulting DNA fragments are separated by electrophoresis using an electric current to move them through a sieve-like gel or matrix, which allows smaller fragments to move faster than larger fragments. The DNA fragments are transferred out of the gel or matrix onto a solid membrane, which is then exposed to a DNA probe labeled with a radioactive, fluorescent, or chemical tag. The tag allows any DNA fragments containing complementary sequences with the DNA probe sequence to be visualized within the Southern blot. The Southern blotting combines the transfer of electrophoresis-separated DNA fragments to a filter membrane in a process called blotting, and the subsequent fragment detection by probe hybridization. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymerase Chain Reaction
The polymerase chain reaction (PCR) is a method widely used to make millions to billions of copies of a specific DNA sample rapidly, allowing scientists to amplify a very small sample of DNA (or a part of it) sufficiently to enable detailed study. PCR was invented in 1983 by American biochemist Kary Mullis at Cetus Corporation. Mullis and biochemist Michael Smith (chemist), Michael Smith, who had developed other essential ways of manipulating DNA, were jointly awarded the Nobel Prize in Chemistry in 1993. PCR is fundamental to many of the procedures used in genetic testing and research, including analysis of Ancient DNA, ancient samples of DNA and identification of infectious agents. Using PCR, copies of very small amounts of DNA sequences are exponentially amplified in a series of cycles of temperature changes. PCR is now a common and often indispensable technique used in medical laboratory research for a broad variety of applications including biomedical research and forensic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clinical Diagnosis
Medical diagnosis (abbreviated Dx, Dx, or Ds) is the process of determining which disease or condition explains a person's symptoms and signs. It is most often referred to as a diagnosis with the medical context being implicit. The information required for a diagnosis is typically collected from a history and physical examination of the person seeking medical care. Often, one or more diagnostic procedures, such as medical tests, are also done during the process. Sometimes the posthumous diagnosis is considered a kind of medical diagnosis. Diagnosis is often challenging because many signs and symptoms are nonspecific. For example, redness of the skin ( erythema), by itself, is a sign of many disorders and thus does not tell the healthcare professional what is wrong. Thus differential diagnosis, in which several possible explanations are compared and contrasted, must be performed. This involves the correlation of various pieces of information followed by the recognition and d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stem-loop
Stem-loops are nucleic acid Biomolecular structure, secondary structural elements which form via intramolecular base pairing in single-stranded DNA or RNA. They are also referred to as hairpins or hairpin loops. A stem-loop occurs when two regions of the same nucleic acid strand, usually Complementarity (molecular biology), complementary in nucleotide sequence, base-pair to form a double helix that ends in a loop of unpaired nucleotides. Stem-loops are most commonly found in RNA, and are a key building block of many RNA biomolecular structure#Secondary structure, secondary structures. Stem-loops can direct RNA folding, protect structural stability for messenger RNA (mRNA), provide recognition sites for RNA-binding protein, RNA binding proteins, and serve as a Substrate (chemistry), substrate for Enzyme catalysis, enzymatic reactions. Formation and stability The formation of a stem-loop is dependent on the stability of the helix and loop regions. The first prerequisite is the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coding Sequence
The coding region of a gene, also known as the coding DNA sequence (CDS), is the portion of a gene's DNA or RNA that codes for a protein. Studying the length, composition, regulation, splicing, structures, and functions of coding regions compared to non-coding regions over different species and time periods can provide a significant amount of important information regarding gene organization and evolution of prokaryotes and eukaryotes. This can further assist in mapping the human genome and developing gene therapy. Definition Although this term is also sometimes used interchangeably with exon, it is not the exact same thing: the exon can be composed of the coding region as well as the 3' and 5' untranslated regions of the RNA, and so therefore, an exon would be partially made up of coding region. The 3' and 5' untranslated regions of the RNA, which do not code for protein, are termed non-coding regions and are not discussed on this page. There is often confusion between coding ... [...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] |
Myotonic Dystrophy Protein Kinase
Myotonin-protein kinase (MT-PK) also known as myotonic dystrophy protein kinase (MDPK) or dystrophia myotonica protein kinase (DMPK) is an enzyme that in humans is encoded by the '' DMPK'' gene. The DMPK gene product is a Ser/Thr protein kinase homologous to the MRCK p21-activated kinases and Rho kinase family. Data obtained by using antibodies that detect specific isoforms of DMPK indicate that the most abundant isoform of DMPK is an 80-kDa protein expressed almost exclusively in smooth, skeletal, and cardiac muscles. This kinase exists both as a membrane-associated and as a soluble form in human left ventricular samples. The different C termini of DMPK that arise from alternative splicing determine its localization to the endoplasmic reticulum, mitochondria, or cytosol in transfected COS-1 cells. Among the substrates for DMPK proposed by in vitro studies are phospholemman, the dihydropyridine receptor, and the myosin phosphatase targeting subunit. However, an in vivo demonstratio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-linked Spinal And Bulbar Muscular Atrophy
Spinal and bulbar muscular atrophy (SBMA), popularly known as Kennedy's disease, is a rare, adult-onset, X-linked recessive lower motor neuron disease caused by trinucleotide CAG repeat expansions in exon 1 of the androgen receptor (AR) gene, which results in both loss of AR function and toxic gain of function. In men, the disease slowly progresses over decades with bulbar and lower motor neuron loss, muscle denervation, and direct skeletal muscle involvement. The disease causes progressive muscle loss with weakness, fasciculations, and cramps. Weakness of the bulbar muscles follows causing difficulties in speech (dysarthria) and swallowing (dysphagia). Female carriers do not show symptoms. Although there is no cure, supportive intervention can improve mobility and reduce complications. The prevalence of SBMA has been estimated at 2.6:100,000 males. There is no known cure for SBMA. Supportive care is focused on preventing disease complications and maintaining independence.� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Untranslated Region
In molecular genetics, an untranslated region (or UTR) refers to either of two sections, one on each side of a coding sequence on a strand of mRNA. If it is found on the Directionality (molecular biology), 5' side, it is called the Five prime untranslated region, 5' UTR (or leader sequence), or if it is found on the Directionality (molecular biology), 3' side, it is called the Three prime untranslated region, 3' UTR (or trailer sequence). mRNA is RNA that carries information from DNA to the ribosome, the site of protein synthesis (Translation (biology), translation) within a cell. The mRNA is initially Transcription (genetics), transcribed from the corresponding DNA sequence and then translated into protein. However, several regions of the mRNA are usually not translated into protein, including the 5' and 3' UTRs. Although they are called untranslated regions, and do not form the Coding region, protein-coding region of the gene, Upstream open reading frame, uORFs located withi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FMR1
''FMR1'' (Fragile X Messenger Ribonucleoprotein 1) is a human gene that codes for a protein called ''fragile X messenger ribonucleoprotein'', or FMRP. This protein, most commonly found in the brain, is essential for normal cognitive development and female reproductive function. Mutations of this gene can lead to fragile X syndrome, intellectual disability, premature ovarian failure, autism, Parkinson's disease, developmental delays and other cognitive deficits. The FMR1 premutation is associated with a wide spectrum of clinical phenotypes that affect more than two million people worldwide. Function Synaptic plasticity FMRP has a diverse array of functions throughout different areas of the neuron; however these functions have not been fully characterized. FMRP has been suggested to play roles in nucleocytoplasmic shuttling of mRNA, dendritic mRNA localization, and synaptic protein synthesis. Studies of Fragile X syndrome have significantly aided in the understanding of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
