Scientists have devised a rapid genetic DNA test that allows for the diagnosis of many rare diseases of the nerve and muscle with nearly 100% precision.
Tandem repeated diseases are a collection of more than 50 genetic diseases which include Huntington’s disease as well as amyotrophic lateral degeneration (ALS) that are thought to be caused by the short DNA sequences get repeated often.
Tandem repetitions may result from problems with DNA replication which then get passed down to the next generation. They are not always harmful but all living things possess them in various patterns and combinations , which makes them an effective instrument for identifying the relationships between people, such as parentage , or for tracing the roots of illnesses.
Sometimes, however, they are found in troublesome regions within our DNA.
Based on the location they occur depending on the location, abnormally long versions of these repetitive sequences could trigger neuromuscular or neurological degeneration. However, since there are 37 genes associated with Short tandem disorder, it could take several tests before identifying those responsible for a person’s symptoms.
For patients such as John who is one of the patients who took part in a recent study it could take more than 10 years to narrow the choices.
John was later diagnosed with cerebellar aphasia, neuropathy, as well as vestibular are flexia syndrome, also known as CANVAS which is short for cerebellar ataxia, neuropathy and vestibular are flex. It is a neurodegenerative movement disorder, caused by an increase in DNA repeats within the RFC1 gene. RFC1.
Only in this one gene There are numerous ways short DNA sequences may be repeated, making an accurate diagnostic test for all of them difficult.
“I have been taking test after test for more than 10 years with no explanations of the problem” John says. John.
A Neurologist Kishore Kumar says the team he works with at the Garvan Institute for Medical Research in Australia describe this strenuous process as a ‘diagnostic journey’. Patients like John endure years of waiting to get answers, symptoms become each day worse.
There’s currently no cure for the tandem repeat diseases, early detection can aid patients in managing their symptoms and stop some of the diseases’ progression. Therefore, the test that has been developed recently should bring a significant benefit for patients.
“This new test will completely revolutionize how we diagnose these diseases, since we can now test for all the disorders at once with a single DNA test and give a clear genetic diagnosis,” says Kumar, “helping patients avoid years of unnecessary muscle or nerve biopsies for diseases they don’t have, or risky treatments that suppress their immune system.”
The new assessment is built on nano-pore technology that can be used to analyze the length of DNA or RNA fragments in the well-known repetitive areas in the genome of humans.
In the case of a single DNA specimen from a person’s blood researchers are able to move the nucleic acids through an apore made of protein by utilizing variations in the electrical current that result from molecular interactions to identify in real-time sequences of 40 genes that are believed as being linked to the 25 tandem repeat disorders.
In the 37 patients assessed with this test which included John, all of them were found to be a match for their neuro-genetic condition.
“We correctly diagnosed all patients with conditions that were already known, including Huntington’s disease, fragile X syndrome, hereditary cerebellar ataxias, myotonic dystrophies, myoclonic epilepsies, motor neuron disease, and more,” says the genomicist Ira Deveson, also from the Garvan Institute.
The current tests for gene sequencing require equipment as big as refrigerators, but Nanopores are larger than staplers. The cost is also many times less, which means it is able to be easily increased and then distributed.
Researchers are currently working to get the test accepted for clinical use. They are hoping that in about two-five years, the test for diagnosing will be utilized often.
The study was published in Science Advances.