If the confusing numbers and letters in your raw DNA data have left you scratching your head, you aren’t alone. Sites like 23andme, Ancestry, or MyHeritage DNA present your raw DNA data in a tabular format, with one column reserved for RSIDs. But what are RSIDs? Why do they matter? Why do they look so complicated? This article will answer all these questions, telling you everything you need to know about RSIDs and what they mean for your genetic report.
The Basics
The term RSID stands for Reference SNP-cluster IDentification.
RSIDs are standard naming conventions for SNPs.
SNPs are short for single nucleotide polymorphisms.
They represent individual nucleotides on your DNA that have been mutated.
Mutations could happen by chance or be inherited from your parents.
These regions are called polymorphisms because they usually differ from person to person.
Scientists study DNA nucleotide-by-nucleotide (letter-by-letter) against a reference DNA sequence representing the human genome.
If they find a mismatch or a novel region, it is termed an SNP and denoted using an RSID.
RSID Nomenclature
When a researcher identifies an RSID, the mutated sequence is passed through a database that matches the sequence to a known RSID.
The format of an RSID is ‘rs’ followed by a number without a fixed length.
This number is incremental and grows with each new SNP that scientists discover.
A smaller or larger RSID number merely means it was discovered earlier or later, respectively.
It is unrelated to the SNP’s position in the genome and has no other biological significance.
Types Of RSIDs
Scientists usually assign RSIDs to the following genetic variations:
Single-nucleotide Variations
These indicate variations in just one nucleotide.
For instance, nucleotide T may replace nucleotide C at a certain position in your DNA.
Short Multi-nucleotide Variations
These imply variations in more than one nucleotide at a time.
For example, the nucleotide sequence ATCC at a certain position in your DNA may be replaced with the sequence TCGA.
Small Deletions Or Insertions
Deletions or insertions are types of genetic mutations often seen in DNA.
Deletions refer to missing nucleotides.
Say that the reference genome has the nucleotide C at a given position.
Deletion means that your DNA would be missing the C nucleotide at that position, shortening the sequence.
On the other hand, insertions refer to extraneous nucleotides.
For instance, your DNA could have the sequence CTA instead of C at the same position, lengthening the sequence.
Short Tandem Repeats
Short tandem repeats (STRs) are sequences up to 6 nucleotides long that occur repeatedly in your genome.
They are highly polymorphic, meaning they are subject to slight mutations and differ from person to person.
Mutations or changes in STRs in your DNA are thus valid SNPs and are denoted by RSIDs.
Retrotransposable Elements
Retrotransposons are genetic elements that flit around the genome at random.
They replicate several times, inserting DNA sequences at each of their destinations.
Thus, your DNA is bound to have a few retrotransposable elements at random positions.
Significance Of RSIDs
A raw DNA data file contains tens of thousands of RSIDs on average.
However, an RSID doesn’t always spell trouble.
SNPs generally confer an increased likelihood of you having a particular trait.
These traits could be, but are not limited to:
- How easily you fall asleep at night
- How sensitive you are to caffeine
- What medicines or foods you could be allergic to
- Your risk of diseases like Alzheimer’s, heart conditions, or diabetes
- How well you digest and utilize certain nutrients.
- Facets of your personality, like empathy and anger management
Dozens of RSIDs govern any given trait.
Some RSIDs have more significant effects than others.
Their collective effect determines the presence of the trait in your DNA.
Genetic analysis companies weigh all the RSIDs in your DNA based on their significance to make recommendations for your lifestyle and well-being.
Frequently Asked Questions
What Is The Difference Between RSIDs and SNPs?
RSIDs and SNPs are one and the same.
SNPs are changes in your DNA, and RSIDs are methods of notating them.
Are SNPs Mutations?
SNPs are unexpected changes in the genome.
Thus, they can be termed mutations.
However, not all mutations are SNPs.
How Do You Detect An SNP?
Restriction fragment length polymorphism (RFLP) is the simplest method to detect SNPs.
Certain enzymes can recognize specific sequences in DNA to cleave it at that position.
The presence of an SNP in these sequences would render the enzyme unable to cleave the DNA.
Thus, longer fragments indicate the presence of a SNP.
Summary: What Are RSIDs?
- RSIDs are short for Reference SNP-cluster Identifications.
- They are identification codes for single nucleotide polymorphisms (SNPs)
- SNPs are minor changes in every human’s DNA that influence their trait makeup
- RSIDs are numbered based on how recently they were discovered.
- They could be changes in one or more nucleotides, short tandem repeats, or retrotransposable segments in the genome.
- Several RSIDs influence one trait, and their cumulative effect can assess the presence or absence of a trait in a person.
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References
https://customercare.23andme.com/hc/en-us/articles/212196908-What-Are-RS-Numbers-Rsid
https://www.ncbi.nlm.nih.gov/snp/docs/RefSNP_about
https://www.britannica.com/science/retrotransposon
https://www.genome.gov/genetics-glossary/Restriction-Fragment-Length-Polymorphism
