How large a sample is required for a DNA analysis?

Posted by Jack on December 14, 2022
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    While we can work with any sample type, our lab does prefer either buccal swabs or blood samples. Most of our tests require a minimum amount of DNA to process and interpret results. We'll always let you know ahead of time how much DNA is required so you can plan accordingly. And if your situation is unique, like there's not enough DNA from your source specimen, we'll discuss other options with you before testing begins.

    The amount of DNA required for analysis varies by the type of test.

    The amount of DNA required for analysis varies by the type of test. The two most common types of DNA tests are traditional STR (short tandem repeat) analysis and Next Generation Sequencing (NGS), which are both used to generate a DNA profile report.

    Traditional STR analysis relies on PCR amplification to increase the amount of DNA present, followed by electrophoresis to separate out specific regions based on size and charge. In this case, you'll need enough cells to grow bacteria in your lab—the more cells there are, the better! On average, you'll need about 100 nanograms (ng) per sample for an acceptable result; however this may vary depending on what kind of genetic markers you're looking at. If you're just trying to find out who's related to whom in a family tree situation where everyone has about one million total mutations shared between them all anyway then having less than 100 ng per person might work fine but if anyone has over three million shared mutations then getting at least 300 ng per person is recommended because otherwise results won't interpret accurately due to low signal levels from so many closely related individuals contributing signals from multiple alleles simultaneously (which is why it's best practice not reuse vials).

    Tests for heritable and somatic mutations

    The amount of DNA required for a particular test depends on the type of mutation being tested and whether it is heritable or somatic.

    When testing for somatic mutations, like those associated with cancer, only one cell is tested. We require about 50 ng (nanograms) of DNA from each cell.

    When testing for heritable mutations that can be passed on to your children (such as BRCA1/2), we recommend about 100 ng per sample because these mutations can be present in more than one copy within cells.

    Tests for genetic diseases

    If you're thinking about getting a DNA test for a genetic disease, then the answer is simple: grab a blood sample. Blood samples are always needed in order to test for genetic diseases, but they can be collected in several different ways depending on where the sample comes from and how much of it there is. The most common way to collect blood for DNA testing is by using an oral swab that looks like a small cotton swab (or Q-tip) dipped in alcohol or rubbing alcohol. The medical professional will rub this over your inner cheek for about 20 seconds and then discard it before collecting another sample from someone else or from yourself in another location (e.g., your hand).

    If you have long hair, some labs may ask you if they can take a small piece of hair instead of using an oral swab—this tends not to cause any discomfort or pain on its own but does require some preparation time at home beforehand because longer hair needs more cutting than shorter hair does; so if this applies to you then talk with professionals at each lab before making any decisions!

    Size requirements for testing

    The amount of DNA required to test a sample depends on the type of test you are running. The more complex the type and analysis, the more DNA is needed. For example, a simple STR-based test can be performed with as little as 0.01 micrograms (mcg) of DNA whereas a full genome sequencing requires 1–2 mg of high quality DNA.

    Here’s another way to look at it: If your sample has been degraded or has degraded over time, meaning it is not in very good shape and therefore may have lost some of its integrity, then more material will need to be used in order to produce reliable results

    Since there is no single best way to get DNA, we can work with your unique situation.

    In fact, we can analyze a sample as small as 10 nanograms of DNA.

    The amount of DNA you need for your test depends on the type of genetic test you are getting and what kind of sample is available. For example, if you want to test for a gene that causes Huntington's disease (HD), then all you need is a cheek swab from the inside of your mouth or blood drawn from a vein. However, if you want to use it in paternity testing or other types of DNA analysis, then more than one person (such as both parents) will likely have to provide samples. In this case, we usually recommend asking the people who are being tested for their entire genome sequence which is called whole genome sequencing or WGS for short.

    We understand that there isn't always enough time or money available for this level of genetic testing so we work with each client individually based on their needs and goals so they can achieve them within their budget constraints while still obtaining accurate results."


    At Genetic Testing Labs, we have years of experience in DNA testing and analysis. We are ready to help you understand the size of your sample that is required for your test and answer any other questions you may have. Contact us today!

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