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

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Louisiana Student Standards for Science

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Life Sciences

Biological Evolution: Unity And Diversity

HS-LS4-1

comparing-copy-number-variations-and-snps

Comparing Copy Number Variations and SNPs

Genomic variations such as addition or deletion of segments of DNA are commonly observed in a population. Genomic variations in a population can arise due to single nucleotide changes in the DNA or structural changes to chromosomes.
Copy number variation or CNV is an umbrella term that defines the structural variations involving DNA segments of more than 1 kilo base pair.
If the chromosomal segment involved contains a gene, the CNVs can increase the copy number of that gene by duplication and insertion or decrease it by deletion that results in null genotype.
Therefore, some individuals may have two or even more copies of a gene, or no copies at all. For example, some people of European genetic ancestry may carry two copies of the Rhesus blood group gene, RHD, while some may have just one and others none at all. &#160;
CNV can affect the phenotypes that are dependent on the number of functional gene copies. In European-American and Asian regions where starch-based diets are common, the population shows a higher copy number of gene AMY1, a gene which is involved in starch metabolism.
CNVs are also linked with several diseases such as psoriasis, Parkinson&#8217;s and behavioral disorders like autism and Schizophrenia.
While CNVs usually cover large DNA sequence variations, single nucleotide polymorphisms or SNPs are random, single base substitutions found throughout the genome.
Such base substitutions occur once every 1000 nucleotides; however, not all of them qualify as SNPs. Generally, only a nucleotide variation that is found in more than 1% of the population is referred to as SNP.
SNPs can confer various diseases such as diabetes or cancer. For example, in patients with sickle cell anemia, a single base substitution from adenine to thymine in a specific locus of the beta-globin gene causes sickle-shaped red blood cells.

comparing copy number variations and snps

Sequencing of the human genome has opened up several best-kept secrets of the genome. Scientists have identified thousands of genome variations that exist within a population. These variations can be a single nucleotide or a larger chromosomal variation.
Copy number variations or CNVs are the structural variations that cover more than 1kb of DNA sequence. The single nucleotide polymorphism (SNP), on the other hand, is a single nucleotide change or a point mutation that is found in more than 1% of the population. Both CNV and SNPs are immensely valuable in genetic screening studies and kinship analysis.
<h4>Forms of CNVs. </h4>
There are five forms of CNVs. The first is called a deletion. A loss of a DNA segment can reduce&#160; the copy number of a gene or a group of genes. The second is called tandem duplication. Here, a copy of a chromosomal segment is inserted into an adjacent region. The third is called noncontiguous duplication. Here, a chromosomal segment duplicates and inserts into a distant chromosomal region or a different chromosome. The fourth form is called Multiallelic CNV. A segment of DNA duplicates several times and results in the formation of multiple alleles of a gene. The fifth form is called complex rearrangement. Here a segment of DNA duplicates and inverts before being inserted back into the same or different chromosome.
<h4>Single Nucleotide Polymorphism</h4>
Single Nucleotide Polymorphism or SNP is another type of genomic variation involving alterations in a single nucleotide base. Scientists have identified thousands of SNPs throughout the human genome, and they are routinely used as genetic markers for inherited diseases and forensic analysis.
Based on their application, SNPs are divided into four types. Identity-testing SNPs are used to differentiate people and eliminate people from familial connections. Lineage informative SNPs are tightly linked SNPs that help identify missing individuals in a familial analysis. Ancestry informative SNPs help establish a person&#8217;s ancestry and connect it with their phenotypic characteristics. Phenotype informative SNPs establish the probability of inheriting a particular phenotype, such as skin color, eye color, etc.

Sequencing of the human genome has opened up several best-kept secrets of the genome. Scientists have identified thousands of genome variations that exist ...

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KEY TERMS AND CONCEPTS

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

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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

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Ohio’s Learning Standards and Model Curriculum

9-12

Biology

Evolution

Speciation

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Heredity

BIO1.LS3.2

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BIO.5

BIO.5.d

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Biological Evolution: Unity and Diversity

Arizona Science Standards

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HS-LS4-5

Genome Variation in CNVs and SNPs

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