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Segmental Duplication
Low copy repeats (LCRs), also known as segmental duplications (SDs), or duplicons, are DNA sequences present in multiple locations within a genome that share high levels of sequence identity. Repeats The repeats, or duplications, are typically 10–300 kb in length, and bear greater than 95% sequence identity. Though rare in most mammals, LCRs comprise a large portion of the human genome owing to a significant expansion during primate evolution. In humans, chromosomes Y and 22 have the greatest proportion of SDs: 50.4% and 11.9% respectively. SRGAP2 is an SD. Misalignment of LCRs during non-allelic homologous recombination (NAHR) is an important mechanism underlying the chromosomal microdeletion disorders as well as their reciprocal duplication partners. Many LCRs are concentrated in "hotspots", such as the 17p11-12 region, 27% of which is composed of LCR sequence. NAHR and non-homologous end joining (NHEJ) within this region are responsible for a wide range of disorders, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base Pair
A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA and RNA. Dictated by specific hydrogen bonding patterns, "Watson–Crick" (or "Watson–Crick–Franklin") base pairs (guanine–cytosine and adenine–thymine) allow the DNA helix to maintain a regular helical structure that is subtly dependent on its nucleotide sequence. The Complementarity (molecular biology), complementary nature of this based-paired structure provides a Redundancy (information theory), redundant copy of the genetic information encoded within each strand of DNA. The regular structure and data redundancy provided by the DNA double helix make DNA well suited to the storage of genetic information, while base-pairing between DNA and incoming nucleotides provides the mechanism through which DNA polymerase replicates DNA and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smith–Magenis Syndrome
Smith–Magenis syndrome (SMS), also known as 17p-microdeletion syndrome, is a microdeletion syndrome characterized by an abnormality in the short (p) arm of chromosome 17. It has features including intellectual disability, facial abnormalities, difficulty sleeping, and numerous behavioral problems such as self-harm. Smith–Magenis syndrome affects an estimated between 1 in 15,000 to 1 in 25,000 individuals. Signs and symptoms Facial features of children with Smith–Magenis syndrome include a broad and square face, deep-set eyes, large cheeks, and a prominent jaw, as well as a flat nose bridge (in the young child; as the child ages it becomes more ski-jump shaped). Eyes tend to be deep-set, close together, and slanted upwards. Eyebrows are heavy with lateral extension. The mouth is the most noticeable feature; both upper and lower lips are full, and the mouth is wide. The mouth curves downwards and the upper lip curves outwards, due to a fleshy philtrum. These facial features b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tandem Exon Duplication
Tandem exon duplication is defined as duplication of exons within the same gene to give rise to the subsequent exon. A complete exon analysis of all genes in ''Homo sapiens'', ''Drosophila melanogaster'', and ''Caenorhabditis elegans'' has shown 12,291 instances of tandem duplication in exons in human, fly, and worm. Analysis of the intronic region has produced further 4,660 unidentified duplicated exons referred to as unannotated exons. 1,578 of these unannotated exons contained stop codons thus not considered potential exons. 35.1% of the unannotated exons were found in the EST sequence thus confirming the potential of the presence of these exons in protein transcripts. See also * Exon shuffling * Gene duplication Gene duplication (or chromosomal duplication or gene amplification) is a major mechanism through which new genetic material is generated during molecular evolution. It can be defined as any duplication of a region of DNA that contains a gene ... References ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inparanoid
Inparanoid is an algorithm that finds orthologous genes and paralogous genes that arose—most likely by duplication—after some speciation event. Such protein-coding genes are called ''in-paralogs'', as opposed to ''out-paralogs'' (which arose prior to a species split). Inparanoid (with varying capitalization) may refer to a program that uses the INPARANOID algorithm, or to the derived database of orthologous clusters of genes. See also * BLAST * Proteomics Proteomics is the large-scale study of proteins. Proteins are vital macromolecules of all living organisms, with many functions such as the formation of structural fibers of muscle tissue, enzymatic digestion of food, or synthesis and replicatio ... References External links InParanoid Speciation {{bioinformatics-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comparative Genomics
Comparative genomics is a branch of biological research that examines genome sequences across a spectrum of species, spanning from humans and mice to a diverse array of organisms from bacteria to chimpanzees. This large-scale holistic approach compares two or more genomes to discover the similarities and differences between the genomes and to study the biology of the individual genomes. Comparison of Whole genome sequencing, whole genome sequences provides a highly detailed view of how organisms are related to each other at the gene level. By comparing whole genome sequences, researchers gain insights into Genetics, genetic relationships between organisms and study Evolutionary biology, evolutionary changes. The major principle of comparative genomics is that common features of two organisms will often be encoded within the DNA that is evolutionarily Conserved sequence, conserved between them. Therefore, Comparative genomics provides a powerful tool for studying evolutionary chang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Evolution
Molecular evolution describes how Heredity, inherited DNA and/or RNA change over evolutionary time, and the consequences of this for proteins and other components of Cell (biology), cells and organisms. Molecular evolution is the basis of phylogenetics, phylogenetic approaches to describing the Tree of life (biology), tree of life. Molecular evolution overlaps with population genetics, especially on shorter timescales. Topics in molecular evolution include the origins of new genes, the genetic nature of complex traits, the genetic basis of adaptation and speciation, the Evolutionary developmental biology, evolution of development, and patterns and processes underlying genome, genomic changes during evolution. History The history of molecular evolution starts in the early 20th century with comparative biochemistry, and the use of "fingerprinting" methods such as immune assays, gel electrophoresis, and paper chromatography in the 1950s to explore homologous proteins. The advent of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudogenes
Pseudogenes are nonfunctional segments of DNA that resemble functional genes. Pseudogenes can be formed from both protein-coding genes and non-coding genes. In the case of protein-coding genes, most pseudogenes arise as superfluous copies of functional genes, either directly by gene duplication or indirectly by reverse transcription of an mRNA transcript. Pseudogenes are usually identified when genome sequence analysis finds gene-like sequences that lack regulatory sequences or are incapable of producing a functional product. Pseudogenes are a type of junk DNA. Most non-bacterial genomes contain many pseudogenes, often as many as functional genes. This is not surprising, since various biological processes are expected to accidentally create pseudogenes, and there are no specialized mechanisms to remove them from genomes. Eventually pseudogenes may be deleted from their genomes by chance of DNA replication or DNA repair errors, or they may accumulate so many mutational changes tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coverage (genetics)
In genetics, coverage is one of several measures of the depth or completeness of DNA sequencing, and is more specifically expressed in any of the following terms: *Sequence coverage (or depth) is the number of unique reads that include a given nucleotide in the reconstructed sequence. Deep sequencing refers to the general concept of aiming for high number of unique reads of each region of a sequence. *Physical coverage, the cumulative length of reads or read pairs expressed as a multiple of genome size. *Genomic coverage, the percentage of all base pairs or loci of the genome covered by sequencing. Sequence coverage Rationale Even though the sequencing accuracy for each individual nucleotide is very high, the very large number of nucleotides in the genome means that if an individual genome is only sequenced once, there will be a significant number of sequencing errors. Furthermore, many positions in a genome contain rare single-nucleotide polymorphisms (SNPs). Hence to distingu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potocki–Lupski Syndrome
Potocki–Lupski syndrome (PTLS), also known as dup(17)p11.2p11.2 syndrome, trisomy 17p11.2 or duplication 17p11.2 syndrome, is a contiguous gene syndrome involving the microduplication of band 11.2 on the short arm of human chromosome 17 (17p11.2). The duplication was first described as a case study in 1996. In 2000, the first study of the disease was released, and in 2007, enough patients had been gathered to complete a comprehensive study and give it a detailed clinical description. PTLS is named for two researchers involved in the latter phases, Drs. Lorraine Potocki and James R. Lupski of Baylor College of Medicine. PTLS was the first predicted reciprocal of a homologous recombination (microdeletion or microduplication) where both reciprocal recombinations result in a contiguous gene syndrome. Its reciprocal disease is Smith–Magenis syndrome (SMS), in which the chromosome portion duplicated in PTLS is deleted altogether. Potocki–Lupski syndrome is considered a rare di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hereditary Neuropathy With Liability To Pressure Palsies
Hereditary neuropathy with liability to pressure palsy (HNPP) is a peripheral neuropathy, a condition that affects the nerves.update 2014 Pressure on the nerves can cause tingling sensations, numbness, pain, weakness, muscle atrophy and even paralysis of the affected area. In normal individuals, these symptoms disappear quickly, but in sufferers of HNPP even a short period of pressure can cause the symptoms to occur. Palsies can last from minutes or days to weeks or even months. HNPP is caused by a mutation in the gene ''PMP22'', which makes peripheral myelin protein 22. This protein has a role in the maintenance of the myelin sheath that insulates nerves, resulting in insufficient conductivity in the nerves. HNPP is part of the group of hereditary motor and sensory neuropathy (HMSN) disorders and is linked to Charcot–Marie–Tooth disease (CMT). Signs and symptoms Symptoms and symptom onset vary; some individuals are diagnosed in childhood, others in adulthood, some report mino ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
