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

Las variaciones genómicas, como la adición o deleción de segmentos de ADN, se observan comúnmente en una población. Las variaciones genómicas en una población pueden surgir debido a cambios de un solo nucleótido en el ADN o cambios estructurales en los cromosomas.
La variación del número de copias o CNV es un término general que define las variaciones estructurales que involucran segmentos de ADN de más de 1 kilo de pares de bases.
Si el segmento cromosómico involucrado contiene un gen, las CNV pueden aumentar el número de copias de ese gen por duplicación e inserción o disminuirlo por deleción que da como resultado un genotipo nulo.
Por lo tanto, algunos individuos pueden tener dos o incluso más copias de un gen, o ninguna copia en absoluto. Por ejemplo, algunas personas de ascendencia genética europea pueden portar dos copias del gen del grupo sanguíneo Rhesus, RHD, mientras que algunas pueden tener solo una y otras ninguna.  
La CNV puede afectar a los fenotipos que dependen del número de copias de genes funcionales. En las regiones europeo-americanas y asiáticas donde las dietas basadas en almidón son comunes, la población muestra un mayor número de copias del gen AMY1, un gen que está involucrado en el metabolismo del almidón.
Las CNV también están relacionadas con varias enfermedades como la psoriasis, el Parkinson y trastornos del comportamiento como el autismo y la esquizofrenia.
Mientras que las CNV suelen cubrir grandes variaciones en la secuencia de ADN, los polimorfismos de un solo nucleótido o SNP son sustituciones aleatorias de una sola base que se encuentran en todo el genoma.
Tales sustituciones de bases ocurren una vez cada 1000 nucleótidos; sin embargo, no todos ellos califican como SNP. Por lo general, solo una variación de nucleótidos que se encuentra en más del 1% de la población se denomina SNP.
Los SNP pueden conferir diversas enfermedades como la diabetes o el cáncer. Por ejemplo, en pacientes con anemia de células falciformes, una sustitución de una sola base de adenina a timina en un locus específico del gen de la beta-globina causa glóbulos rojos en forma de hoz.

<ol>
	<li>Lee, Charles y Stephen W. Scherer. "El contexto clínico de la variación del número de copias en el genoma humano". Revisiones de expertos en medicina molecular 12 (2010).</li>
	<li>Budowle, Bruce y Angela Van Daal. "Clases de SNP forensemente relevantes". Biotechniques 44, no. 5 (2008): 603-610.</li>
</ol>

comparación de variaciones del número de copias y snp

La secuenciación del genoma humano ha revelado varios de los secretos mejor guardados del genoma. Los científicos han identificado miles de variaciones genómicas que existen dentro de una población. Estas variaciones pueden ser un solo nucleótido o una variación cromosómica más grande.

Las variaciones en el número de copias o CNV son variaciones estructurales que cubren más de 1 kb de secuencia de ADN. El polimorfismo de un solo nucleótido (SNP), por otro lado, es un cambio de un solo nucleótido o una mutación puntual que se encuentra en más del 1% de la población. Tanto los CNV como los SNP son inmensamente valiosos en estudios de detección genética y análisis de parentesco.

Formas de CNV.

Hay cinco formas de CNV. La primera se llama eliminación. La pérdida de un segmento de ADN puede reducir el número de copias de un gen o de un grupo de genes. El segundo se llama duplicación en tándem. Aquí, se inserta una copia de un segmento cromosómico en una región adyacente. La tercera se llama duplicación no contigua. Aquí, un segmento cromosómico se duplica y se inserta en una región cromosómica distante o en un cromosoma diferente. La cuarta forma se llama CNV multialélica. Un segmento de ADN se duplica varias veces y da como resultado la formación de múltiples alelos de un gen. La quinta forma se llama reordenamiento complejo. Aquí, un segmento de ADN se duplica y se invierte antes de volver a insertarse en el mismo cromosoma o en uno diferente.

Polimorfismo de nucleótido simple

El polimorfismo de un solo nucleótido o SNP es otro tipo de variación genómica que implica alteraciones en una sola base de nucleótido. Los científicos han identificado miles de SNP en todo el genoma humano y se utilizan habitualmente como marcadores genéticos para enfermedades hereditarias y análisis forenses.

Según su aplicación, los SNP se dividen en cuatro tipos. Los SNP de prueba de identidad se utilizan para diferenciar personas y eliminarlas de conexiones familiares. Los SNP informativos de linaje están estrechamente vinculados y ayudan a identificar individuos desaparecidos en un análisis familiar. Los SNP informativos sobre ascendencia ayudan a establecer la ascendencia de una persona y conectarla con sus características fenotípicas. Los SNP informativos del fenotipo establecen la probabilidad de heredar un fenotipo particular, como el color de piel, el color de ojos, etc.

Comparación de variaciones del número de copias y SNP

La secuenciación del genoma humano ha sacado a la luz varios secretos mejor guardados del genoma. Los científicos han identificado miles de variaciones del genoma que existen ...

Education

Educación

JoVE Core

Molecular Biology

Biología Molecular

Unit 2

Unidad 2

Genomes and Evolution

Genomas y evolución

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

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

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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 Biología Molecular presenta los procesos moleculares de la célula a través de lecciones claras y concisas de animaciones audiovisuales. Además, en los vídeos de científicos en acción, se muestran aplicaciones de estos conceptos mediante experimentos reales en laboratorios especializados.

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9-12

Biology

Evolution

Speciation

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Heredity

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BIO.5

BIO.5.d

Minnesota Academic Standards in Science

Life Science

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Arizona Science Standards

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Genome Variation in CNVs and SNPs

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