A Single DNA Test Can Now Screen For More Than 50 Genetic Diseases

Since its inception, genetic testing has proven to be cutting-edge technology that helps provide insight into many conditions and diseases. There are currently more than 77,000 genetic tests used across the world.¹

Unique DNA tests were historically needed to better understand each disease, but this can be tedious when trying to test for several at once.

A team of researchers and scientists at UCL Queen Square Institute of Neurology, led by the Garvan Institute of Medical Research in Sydney, has developed a single DNA test capable of identifying over 50 genetic neurological and neuromuscular diseases.

So, how does the test work? It uses cutting-edge technology called Nanopore sequencing to scan a person’s genome.

The technology is smaller and cheaper than that used in standard tests. The researchers who developed the technology hope it will be used as part of routine diagnostic practices in two to five years once clinical accreditation has been acquired.²

Read on to learn more about how this DNA test works and what this revolutionary discovery means for modern-day healthcare.

The link between genes and disease

Family history is one of the most common risk factors for many diseases. This means your risk of developing a certain condition is greater if your parent, sibling, or other close relative has it or is a genetic carrier of that condition.

For instance, Huntington’s disease is caused by an alteration of the HTT gene. This altered gene is typically inherited from a parent. In fact, it’s rare for a person with Huntington’s disease not to have a parent who either has the disorder or carries the altered gene.³

Genetic diseases can be classified into the following three types:⁴

Monogenic diseases

Even a single altered gene can cause a genetic disease. Diseases that fall in this category are called monogenic diseases or single-gene disorders. Huntington’s disease is a common example.

Chromosomal diseases

These diseases are caused by alterations to your chromosomes. A chromosome is found in your cells and is made up of your DNA. A chromosomal disorder could be caused by missing or extra chromosomes in your genome.

Multifactorial diseases

Most diseases in the world today are multifactorial. Variations in multiple genes cause them. Environmental and lifestyle factors may sometimes influence the development of these diseases too.

Identifying multifactorial diseases with genetic testing can be challenging, as identifying each gene that contributes to the development of the condition can be difficult. These are also known as complex disorders.

How DNA tests screen for genetic diseases

Your DNA contains a wealth of genetic information. The average human has between 20,000 to 25,000 genes, divided into two sets. Each set of genes is inherited from your parents. A single gene alteration can cause you to develop a specific condition or put you at risk of having a child who develops a single-gene disorder.⁵

Research shows there are currently up to 5,000 conditions linked to hereditary causes. Genetic disorders account for up to 80% of rare diseases, making genetic testing crucial for getting ahead of them.⁶ ⁷

While this might seem troubling, it’s crucial to note that genetics isn’t the only thing responsible for many hereditary diseases. Environmental factors and lifestyle habits can also make you more or less susceptible to developing a specific condition.

Benefits of genetic testing

The primary benefit of genetic testing in healthcare is to provide greater insight into your health. People who are seemingly healthy and fit can also benefit from genetic testing, especially if they plan to have children.

Testing positive for a genetic mutation arms you with the information you need to take steps to prevent or get ahead of a condition. Getting a negative result, on the other hand, gives you a sense of relief and knowledge that you are not susceptible to particular diseases.

Other benefits of genetic testing include the following:

• Educating yourself and your family about hereditary diseases and their risks

• Gaining a better understanding of a hereditary disease you or a family member has been diagnosed with

• Preventing or lowering your risk of developing genetic diseases you may be susceptible to

How well do genetic tests work?

Research shows that the newly developed DNA test is more efficient at identifying neurological and neuromuscular genetic diseases that are typically hard to diagnose.

In a recent study, scientists found that the test correctly identified conditions like Huntington’s disease, Fragile X syndrome, hereditary cerebellar ataxias, myotonic dystrophies, myoclonic epilepsies, and motor neuron disease.⁸

Each disease the test can screen for belongs to a group of conditions called short tandem repeat expansion disorders. These conditions are typically challenging to diagnose as they tend to cause a person to exhibit a complex set of symptoms. The new DNA test solves this problem by simultaneously screening for all short tandem repeat expansion disorders. This helps your doctor pinpoint which condition is responsible for your symptoms.

The accuracy of genetic testing depends on a combination of factors.

First is analytical validity. This refers to how well a test can predict if you have a particular genetic mutation or variation.

Next is clinical validity, which determines how well the identified genetic variant is associated with a specific disorder.

Finally, a test’s clinical utility determines if the test is capable of providing helpful information about the treatment, diagnosis, prevention, and management of the identified disorder.⁹

Risks and limitations of genetic testing

Concerning you and your health, genetic testing has no downsides.

The process of getting a genetic test carries minimal risk. In most cases, you’ll need to provide a small blood sample by pricking your finger or having blood drawn from a vein. A buccal smear, where samples of cells are taken from the inside of your cheek with a swab, is another common way to obtain biological samples for a genetic test.

Tests can provide a wealth of genetic information about hereditary diseases that can help you get ahead of conditions you may have a high risk of developing. It also helps protect and prevent any children you may have from developing conditions that may have been unknowingly passed down to them.

One significant drawback of genetic testing is its cost.

The cost starts at about $100 and runs up to $2,000, depending on the type of test you undertake. More complex tests cost more. More than one test is necessary, in some cases, which can also drive up the cost.¹⁰

The high cost of genetic testing creates an accessibility problem, where people understand its importance and benefits but can’t afford to pay for it. It also means that people who are seemingly fit and healthy and showing no signs of disease may not prioritize taking a genetic test. 

In some cases, genetic testing may inadvertently reveal private family information. For instance, paternity fraud can be revealed, which occurs when a mother deliberately misidentifies the biological father of her child. Understandably, these circumstances can create feelings of anger and resentment, causing family tension.

Where a genetic test reveals that you have an increased risk of developing a particular condition, it can lead to anxiety, fear, and depression. Getting counseling before and after genetic testing is essential to prepare you for the process and what your results might reveal.

Knowing there’s a limit to how much information you can get from a genetic test is crucial. While most tests can accurately predict if you are at high risk of developing particular conditions, they don’t reveal when symptoms are likely to begin or how severe they could be. They also rarely offer any insight into how best to treat hereditary conditions.

Genetic testing isn’t a perfect science. Allowing for lab and human error is essential when considering results. Consult a genetic counselor to reduce this risk. They are trained healthcare providers who will help look into your personal and familial medical history. They’ll help you determine which genetic tests are best for you based on what you want from genetic testing.¹¹

Types of genetic tests

There are several types of genetic tests. Here are some of the most common types:

Newborn screening

These tests are carried out on newborns to identify any genetic conditions they may have inherited. Identifying and treating these disorders is crucial to prevent complications and, in some cases, death.

Carrier testing

This is a good idea for people who plan to have children. Carrier testing determines if a person is carrying a particular gene mutation. A child of two carriers may inherit a genetic disorder. Sickle cell disease is one of the most common examples.¹²

Prenatal testing

Prenatal testing can help identify any alteration or mutation in your baby’s genes. While this doesn’t always confirm the baby has inherited a genetic disorder, it’s highly recommended when there’s a risk that they may have one.

Unfortunately, the genetic tests that can be conducted while your child is in the womb are limited, meaning you may not be able to accurately identify all possible congenital disabilities and inherited conditions.

Predictive testing

This is carried out later in life to determine if you have developed any genetic mutations that may be associated with a disease or disorder.

Predictive testing is helpful for people who have family members with a condition and are worried about developing the disorder in the future, even if they are not currently presenting symptoms.

For example, a person whose mother or aunt has breast cancer should consider testing for the BRCA1 gene, which is linked with an increased risk of breast cancer. This gene has also been linked to ovarian, prostate, and pancreatic cancer.¹³

Preimplantation genetic testing

This type of genetic testing is helpful for couples at risk of having a child with a specific genetic condition. It’s performed on an embryo before it’s transferred into the uterus. It helps to identify any abnormal genes that could cause a failed IVF cycle or miscarriage.¹⁴

Diagnostic testing

This type of testing can help diagnose a condition you are exhibiting symptoms of. It can also rule out other conditions that share the same symptoms.

Forensic testing

Forensic testing has no health benefits. It is used to identify an individual, typically for legal purposes.

A paternity test to help identify a person’s father is a common type of forensic testing. It is also helpful for identifying a person whose physical features are damaged due to an accident or natural disaster.

Genetic testing and the future of modern-day healthcare

The first known genetic tests in healthcare were conducted around the year 1947. Since then, the technology facilitating genetic tests has developed and progressed.

Genetic testing used to be focused on preventing disabilities. However, it has since shifted to helping us understand how the human genome works, especially concerning our overall health.

A DNA test that can identify and distinguish between 50 short tandem repeat expansion disorders, such as Huntington’s disease and Fragile X syndrome, is a game changer in medical diagnostics.

Unfortunately, these disorders have no cure. However, genetic testing aids in early detection, which helps your doctor prevent and treat complications earlier. A DNA test can also accurately predict your chances of developing or passing down a condition to your child.

The lowdown

Genetic testing provides valuable information that can help advance the treatment and management of several hereditary conditions.

It also informs family planning for people who want to have children, as it helps to make people aware of congenital conditions that can be passed down. In cases where a genetic condition has been passed down, it enables you to get ahead by formulating a treatment and management plan with your doctor.

Sources:

1. What is genetic testing? | MedlinePlus

2. Single test for over 50 genetic diseases will cut diagnosis from decades to days (2022)

3. Huntington disease | MedlinePlus

4. Genetic disorders | MedlinePlus

5. Mendelian genetics: Patterns of inheritance and single-gene disorders (2008)

6. Human genetic screening (1999)

7. Spotlight on rare diseases (2019)

8. Comprehensive genetic diagnosis of tandem repeat expansion disorders with programmable targeted nanopore sequencing (2022)

9. How can I be sure a genetic test is valid and useful? | MedlinePlus

10. What is the cost of genetic testing, and how long does it take to get the results? | MedlinePlus

11. Genetic counseling | Centers for Disease Control and Prevention

12. Carrier screening | American College of Obstetricians and Gynecologists

13. BRCA1- and BRCA2-associated hereditary breast and ovarian cancer (1998)

14. Preimplantation genetic testing (PGT) | Johns Hopkins Medicine

Toketemu Ohwovoriole is a healthcare writer who has spent the last six years creating content for companies and publications around the globe. She has been featured in The Huffington Post, Insider, Verywell, and other major publications. Her previous work delves into the mental and physical health effects of birth control, overall wellness, and sensitive women's healthcare issues.