Name: genome variation in cnvs and snps
Uploaded: 2021-04-07T12:11:59.000Z
Duration: 2 min 26 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Life Sciences

Biological Evolution: Unity And Diversity

HS-LS4-1

comparing-copy-number-variations-and-snps

Comparing Copy Number Variations and SNPs

Variações genômicas, como adição ou deleção de segmentos de DNA, são comumente observadas em uma população. Variações genômicas em uma população podem surgir devido a alterações de nucleotídeo único no DNA ou alterações estruturais nos cromossomos.
Variação do número de cópias ou CNV é um termo abrangente que define as variações estruturais envolvendo segmentos de DNA de mais de 1 par de bases de quilo.
Se o segmento cromossômico envolvido contiver um gene, as CNVs podem aumentar o número de cópias desse gene por duplicação e inserção ou diminuí-lo por deleção que resulta em genótipo nulo.
Portanto, alguns indivíduos podem ter duas ou até mais cópias de um gene, ou nenhuma cópia. Por exemplo, algumas pessoas de ascendência genética europeia podem carregar duas cópias do gene do grupo sanguíneo Rhesus, RHD, enquanto algumas podem ter apenas uma e outras nenhuma.  
A CNV pode afetar os fenótipos que dependem do número de cópias funcionais do gene. Nas regiões euro-americanas e asiáticas onde as dietas à base de amido são comuns, a população mostra um maior número de cópias do gene AMY1, um gene que está envolvido no metabolismo do amido.
As CNVs também estão ligadas a várias doenças, como psoríase, Parkinson e distúrbios comportamentais como autismo e esquizofrenia.
Enquanto as CNVs geralmente cobrem grandes variações de sequência de DNA, os polimorfismos de nucleotídeo único ou SNPs são substituições aleatórias de base única encontradas em todo o genoma.
Tais substituições de bases ocorrem uma vez a cada 1000 nucleotídeos; no entanto, nem todos eles se qualificam como SNPs. Geralmente, apenas uma variação de nucleotídeo encontrada em mais de 1% da população é chamada de SNP.
Os SNPs podem conferir várias doenças, como diabetes ou câncer. Por exemplo, em pacientes com anemia falciforme, uma substituição de base única de adenina por timina em um locus específico do gene da globina beta causa glóbulos vermelhos em forma de foice.

<ol>
	<li>Lee, Charles e Stephen W. Scherer. "O contexto clínico da variação do número de cópias no genoma humano." Revisões de especialistas em medicina molecular 12 (2010).</li>
	<li>Budowle, Bruce e Angela Van Daal. "Classes SNP forensemente relevantes." Biotécnicas 44, nº 5 (2008): 603-610.</li>
</ol>

comparando variações de número de cópias e snps

O sequenciamento do genoma humano revelou vários segredos mais bem guardados do genoma. Os cientistas identificaram milhares de variações do genoma que existem dentro de uma população. Essas variações podem ser um único nucleotídeo ou uma variação cromossômica maior. Variações no número de cópias ou CNVs são variações estruturais que cobrem mais de 1kb de sequência de DNA. O polimorfismo de nucleotídeo único (SNP), por outro lado, é uma alteração de nucleotídeo único ou uma mutação pontual encontrada em mais de 1% da população. Tanto o CNV quanto os SNPs são imensamente valiosos em estudos de triagem genética e análise de parentesco. <h4>Formas de CNVs. </h4> Existem cinco formas de CNVs. A primeira é chamada de exclusão. A perda de um segmento de DNA pode reduzir o número de cópias de um gene ou grupo de genes. A segunda é chamada duplicação tandem. Aqui, uma cópia de um segmento cromossômico é inserida em uma região adjacente. A terceira é chamada de duplicação não contígua. Aqui, um segmento cromossômico se duplica e se insere em uma região cromossômica distante ou em um cromossomo diferente. A quarta forma é chamada CNV multialélica. Um segmento de DNA se duplica várias vezes e resulta na formação de múltiplos alelos de um gene. A quinta forma é chamada de rearranjo complexo. Aqui, um segmento de DNA se duplica e se inverte antes de ser inserido novamente no mesmo cromossomo ou em um cromossomo diferente. <h4>Polimorfismo de nucleotídeo único</h4> Polimorfismo de Nucleotídeo Único ou SNP é outro tipo de variação genômica que envolve alterações em uma única base de nucleotídeo. Os cientistas identificaram milhares de SNPs em todo o genoma humano, e eles são rotineiramente usados como marcadores genéticos para doenças hereditárias e análises forenses. Com base na sua aplicação, os SNPs são divididos em quatro tipos. Os SNPs de teste de identidade são usados para diferenciar pessoas e eliminar pessoas de conexões familiares. SNPs informativos de linhagem são SNPs fortemente ligados que ajudam a identificar indivíduos desaparecidos em uma análise familiar. Os SNPs informativos de ancestralidade ajudam a estabelecer a ancestralidade de uma pessoa e conectá-la com suas características fenotípicas. Os SNPs informativos do fenótipo estabelecem a probabilidade de herdar um fenótipo específico, como cor da pele, cor dos olhos, etc.

Comparando variações de número de cópias e SNPs

O sequenciamento do genoma humano abriu vários segredos mais bem guardados do genoma. Os cientistas identificaram milhares de variações do genoma que existem ...

Education

JoVE Core

Molecular Biology

Biologia Molecular

Unit 2

Unidade 2

Genomes and Evolution

Genomas e Evolução

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

genome variation in cnvs and snps

Genome variation in CNVs and SNPs shows how DNA can differ across people in a population. These differences may involve a single nucleotide, which is one DNA base, or a larger chromosomal change. Scientists study them to understand inherited variation in the human genome.

Copy number variations, or CNVs, are structural changes that cover more than 1 kb of DNA sequence. A CNV can change the number of copies of a gene or a group of genes. The main forms are deletion, tandem duplication, noncontiguous duplication, multiallelic CNV, and complex rearrangement.

A deletion removes a DNA segment and can lower gene copy number. In tandem duplication, a copied chromosomal segment is inserted next to the original region. In noncontiguous duplication, the copied segment moves to a distant chromosomal region or even a different chromosome. Multiallelic CNV creates several copies and can produce multiple alleles of a gene. In complex rearrangement, a segment duplicates and inverts before it is inserted back into the same or a different chromosome.

Single nucleotide polymorphism, or SNP, is another genomic variation that changes one nucleotide base. A SNP is a point mutation found in more than 1% of the population. Scientists have identified thousands of SNPs across the human genome, and they are widely used as genetic markers in studies of inherited disease and forensic analysis.

SNPs are grouped by use into four types. Identity-testing SNPs help distinguish people and exclude familial connections. Lineage informative SNPs are tightly linked SNPs that help identify missing individuals in family analysis. Ancestry informative SNPs help connect a person's ancestry with related phenotypic traits. Phenotype informative SNPs help estimate the chance of traits such as skin color or eye color.

Genome Variation in CNVs and SNPs

evolutionary relationships through genome comparisons

evolutionary-relationships-through-genome-comparisons

Tracing Evolution with Genome Data

Genome data helps scientists trace how organisms are related over time. When two species share a common feature, it is often encoded by DNA sequences that have stayed conserved in both species. As genome sequencing improved in the late 20th century, researchers gained a better way to compare conserved domains across species and use that evidence to infer evolutionary relationships. Genome comparison can show evolutionary relationships at three levels. At the broadest level, it highlights...

genome copying errors

DNA Replication Error Checks

DNA replication includes built-in error checks that protect the genome during cell division. Even though this process copies millions of base pairs with high fidelity, a wrong base or a longer stretch of wrong bases can still be added to the daughter strands. If these mistakes are not corrected, cells may build up mutations that can threaten survival. One level of repair is proofreading. DNA polymerase enzymes, which build the new DNA strand, can make about 1 incorrect nucleotide per 100,000...

phylogenetic trees

Reading Evolution in Phylogenetic Trees

Phylogenetic trees show how organisms are related through evolution. They map branching patterns that trace common ancestry and help scientists compare species over time. A phylogenetic tree can be read like a family tree for life. Each branch point marks a split from a shared ancestor, and the pattern of branches shows how closely related different organisms are. These trees are used to organize biological information and to study evolutionary change. They can also help scientists understand...

synteny and evolution

Chromosome Rearrangements and Synteny

Chromosome rearrangements and synteny show how shared gene order can reveal evolutionary history. Synteny means genes are found on the same chromosome, even if they are not genetically linked. John H. Renwick coined the term in 1971. Species with common ancestry often keep conserved syntenic regions. Scientists use synteny to compare the evolutionary relationship between species. Human and mouse lineages split from a common ancestor about 80 million years ago. Since then, the ancestral...

multi-species conserved sequences

Conserved DNA Across Species

Conserved DNA across species shows how some genome regions stay nearly unchanged over time. Next-generation sequencing has built large genome databases for many animals and plants. Since the Human Genome Project, scientists have compared the genomes of primates, mammals, and other distant species. These large studies have helped reveal evolutionary relationships between organisms. Although species genomes differ greatly, a few DNA sequences are highly conserved. Conserved DNA sequences found...

gene duplication and divergence

How Duplicate Genes Shape Evolution

Gene duplication helps drive evolution by creating extra copies of DNA that can change over time. The seminal work of Ohno in 1970 helped popularize this idea. DNA sequence comparisons show that many genes in bacteria, archaebacteria, and eukaryotes came from duplication and later divergence, which makes this process important in evolution. The duplicated copies of a gene are called paralogs. When paralogs have similar sequences and functions, they form a gene family. Many gene families have...

exon recombination

How Exons Mix to Form New Genes

Exon recombination helps new genes form by mixing exons from the same gene or from different genes. This process is also called exon shuffling or domain shuffling. It has been seen in vertebrates, invertebrates, and some plants, including potatoes and sunflowers. During exon recombination, exons join in new exon-intron combinations. These new combinations may later become new genes. Exon shuffling follows splice frame rules, which means the exons must fit the reading frame correctly. Each...

comparing copy number variations and snps

Genome variation in CNVs and SNPs shows how DNA can differ across people in a population. These differences may involve a single nucleotide, which is one DNA base, or a larger chromosomal change. Scientists study them to understand inherited variation in the human genome. Copy number variations, or CNVs, are structural changes that cover more than 1 kb of DNA sequence. A CNV can change the number of copies of a gene or a group of genes. The main forms are deletion, tandem duplication,...

key terms and concepts

Explore how copy number variations and SNPs change the human genome, from deletions and duplications to ancestry, identity, and phenotype markers.

Genome Variation in CNVs and SNPs | JoVE K12

molecular biology

JoVE Core Biologia Molecular mostra os processos moleculares da célula através de vídeos de animação claros e concisos. Além disso, nos vídeos de Cientistas em ação, a aplicação desses conceitos é demonstrada por meio de experimentos reais em laboratórios modernos.

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

9-12

Biology

Evolution

Speciation

Tennessee Academic Standards

Heredity

BIO1.LS3.2

Virginia  Standards of Learning

HIgh School

BIO.5

BIO.5.d

Minnesota Academic Standards in Science

Life Science

3.2.1 9L.3.2.1.3

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

Biological Evolution: Unity and Diversity

Arizona Science Standards

HS+B.L4

HS+B.L4U1.13

Next Generation Science Standards

heredity-inheritance-and-variation-of-traits

Heredity: Inheritance and Variation of Traits

HS-LS3-2

new-york-state-science-learning-standards

New York State Science Learning Standards

Inheritance and Variation of Traits

HS-LS3-1.

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Gene Flow

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Construct an explanation based on evidence that biological diversity is influenced by (1) the potential for a species to increase in number, (2) the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for limited resources, and (4) the proliferation of those organisms that are better able to survive and reproduce in the environment. Emphasis is on using evidence to explain the influence each of the four factors has on number of organisms, behaviors, morphology, or physiology in terms of ability to compete for limited resources and subsequent survival of individuals and adaptation of species. Examples of evidence could include mathematical models such as simple distribution graphs or proportional reasoning.

HS-LS4-2

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Apply concepts of statistics and probability to support explanations that populations of organisms adapt when an advantageous heritable trait increases in proportion to organisms lacking this trait. Emphasis is on analyzing shifts in numerical distribution of traits and using these shifts as evidence to support explanations for adaptations. Explanations could include basic statistical or graphical analysis.

HS-LS4-3

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Evaluate evidence supporting claims that changes in environmental conditions can affect the distribution of traits in a population causing: (1) increases in the number of individuals of some species, (2) the emergence of new species over time, and (3) the extinction of other species. Emphasis is on determining cause and effect relationships for how changes to the environment such as deforestation, overfishing, application of fertilizers, drought, flood, and the rate of change of the environment affect distribution or disappearance of traits in species.

HS-LS4-5

Genome Variation in CNVs and SNPs

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