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

Variazioni genomiche come l'aggiunta o la delezione di segmenti di DNA sono comunemente osservate in una popolazione. Le variazioni genomiche in una popolazione possono insorgere a causa di cambiamenti di un singolo nucleotide nel DNA o di cambiamenti strutturali nei cromosomi.
La variazione del numero di copie o CNV è un termine generico che definisce le variazioni strutturali che coinvolgono segmenti di DNA di più di 1 kilo coppia di basi.
Se il segmento cromosomico coinvolto contiene un gene, le CNV possono aumentare il numero di copie di quel gene mediante duplicazione e inserimento o diminuirlo mediante delezione che si traduce in un genotipo nullo.
Pertanto, alcuni individui possono avere due o anche più copie di un gene, o nessuna copia. Ad esempio, alcune persone di origine genetica europea possono essere portatrici di due copie del gene del gruppo sanguigno Rhesus, RHD, mentre alcune possono averne solo una e altre nessuna.  
La CNV può influenzare i fenotipi che dipendono dal numero di copie geniche funzionali. Nelle regioni europee-americane e asiatiche, dove le diete a base di amido sono comuni, la popolazione mostra un numero di copie più elevato del gene AMY1, un gene coinvolto nel metabolismo dell'amido.
Le CNV sono anche collegate a diverse malattie come la psoriasi, il Parkinson e disturbi comportamentali come l'autismo e la schizofrenia.
Mentre le CNV di solito coprono grandi variazioni di sequenza del DNA, i polimorfismi a singolo nucleotide o SNP sono sostituzioni casuali di singole basi che si trovano in tutto il genoma.
Tali sostituzioni di basi si verificano una volta ogni 1000 nucleotidi; tuttavia, non tutti si qualificano come SNP. Generalmente, solo una variazione nucleotidica che si trova in più dell'1% della popolazione è indicata come SNP.
Gli SNP possono conferire varie malattie come il diabete o il cancro. Ad esempio, nei pazienti con anemia falciforme, una sostituzione di una singola base da adenina a timina in un locus specifico del gene della beta-globina provoca globuli rossi a forma di falce.

<ol>
	<li>Lee, Charles e Stephen W. Scherer. "Il contesto clinico della variazione del numero di copie nel genoma umano". Recensioni di esperti in medicina molecolare 12 (2010).</li>
	<li>Budowle, Bruce e Angela Van Daal. "Classi SNP forensemente rilevanti". Biotecniche 44, n. 5 (2008): 603-610.</li>
</ol>

confronto tra variazioni del numero di copie e snp

Il sequenziamento del genoma umano ha svelato diversi segreti meglio custoditi del genoma. Gli scienziati hanno identificato migliaia di variazioni del genoma che esistono all'interno di una popolazione. Queste variazioni possono essere un singolo nucleotide o una variazione cromosomica più ampia.

Le variazioni del numero di copie o CNV sono le variazioni strutturali che coprono più di 1 kb di sequenza di DNA. Il polimorfismo a singolo nucleotide (SNP), d'altra parte, è un cambiamento di un singolo nucleotide o una mutazione puntiforme che si riscontra in più dell'1% della popolazione. Sia CNV che SNP sono immensamente preziosi negli studi di screening genetico e nell'analisi di parentela.

Forme di CNV

Esistono cinque forme di CNV. Il primo si chiama cancellazione. La perdita di un segmento di DNA può ridurre il numero di copie di un gene o di un gruppo di geni. Il secondo è chiamato duplicazione tandem. Qui, una copia di un segmento cromosomico viene inserita in una regione adiacente. La terza è chiamata duplicazione non contigua. Qui, un segmento cromosomico si duplica e si inserisce in una regione cromosomica distante o in un cromosoma diverso. La quarta forma è chiamata CNV multi-allelica. Un segmento di DNA si duplica più volte e dà luogo alla formazione di più alleli di un gene. La quinta forma è chiamata riarrangiamento complesso. Qui un segmento di DNA si duplica e si inverte prima di essere reinserito nello stesso cromosoma o in uno diverso.

Polimorfismo a singolo nucleotide

Il polimorfismo a singolo nucleotide o SNP è un altro tipo di variazione genomica che coinvolge alterazioni in una singola base nucleotidica. Gli scienziati hanno identificato migliaia di SNP in tutto il genoma umano e vengono abitualmente utilizzati come marcatori genetici per malattie ereditarie e analisi forensi.

In base alla loro applicazione, gli SNP si dividono in quattro tipologie. Gli SNP per il test dell'identità vengono utilizzati per differenziare le persone ed eliminare individui dai legami familiari. Gli SNP informativi sul lignaggio sono SNP strettamente collegati che aiutano a identificare gli individui scomparsi in un'analisi familiare. Gli SNP informativi sugli antenati aiutano a stabilire gli antenati di una persona e a collegarli alle sue caratteristiche fenotipiche. Gli SNP informativi sul fenotipo stabiliscono la probabilità di ereditare un particolare fenotipo, come il colore della pelle, il colore degli occhi, ecc.

Confronto tra variazioni del numero di copie e SNP

Il sequenziamento del genoma umano ha rivelato diversi segreti meglio custoditi del genoma. Gli scienziati hanno identificato migliaia di variazioni del genoma che esistono ...

Education

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JoVE Core

Molecular Biology

Biologia Molecolare

Unit 2

Unità 2

Genomes and Evolution

Genomi ed Evoluzione

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

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

Le video animazioni di JoVE Core Molecular Biology, organizzate in video lezioni, illustrano i processi molecolari cellulari in maniera chiara e concisa. Inoltre, nei video di "scienziati in azione", i concetti scientifici vengono applicati e dimostrati da ricercatori attraverso esperimenti in laboratorio.

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Speciation

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BIO.5

BIO.5.d

Minnesota Academic Standards in Science

Life Science

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HS-LS4-5

Genome Variation in CNVs and SNPs

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