New genetic test could detect dozens of hereditary genetic diseases in days

(ORDO NEWS) — A new approach to genetic testing, developed by an international team of scientists, allows much faster, cheaper and more accurate diagnosis of dozens of neurological and neuromuscular diseases.

Patients’ DNA is analyzed only once every few days, instead of the agonizing years of searching for a problematic DNA region using existing methods.

The diseases diagnosed by the new test belong to a class of more than 50 diseases caused by abnormal short tandem repeat (STR) expansion.

STRs are short stretches of DNA (usually two to six base pairs) that are repeated sequentially in some part of the genome. Normally, STRs are found in thousands of places in human DNA (usually 5-50 repeats), which is used in the analysis of relationship and in forensic examination.

Scientists have already shown that STR expansions in more than 40 genes cause hereditary diseases that are difficult to diagnose, often accompanied by pathological changes in the nervous and muscular systems.

Each of these diseases affects between one and 10 people in 100,000, and the list of diseases associated with STR expansion continues to grow.

“These diseases are often difficult to diagnose due to the complex symptoms that patients experience, the complex nature of these repetitive sequences, and the limitations of current genetic testing methods,” said Dr. Ira Deveson , head of genomic technology at the Garvan Institute for Medical Research ( Australia) and senior author of the study.

The authors of a study published in the journal Science Advances clearly show that their test is accurate enough to detect more than 50 neurological and neuromuscular diseases.

Efficiency was demonstrated in 37 patients with an already known diagnosis, confirmed using a new method. The team expects their new technology to be available to the world’s diagnostic practice within the next two to five years.

Genetic tests that exist today do not automatically and simultaneously test several DNA regions where STRs may be located. Therefore, the attending physician, based on the patient’s symptoms and family history, must decide which part of the genome should be tested. However, such near-blind testing can take a very long time.

“When patients show symptoms, it can be difficult to tell which of the known genetic STR expansions they may have.

This testing can go on for years without finding genes associated with the disease. We call this a “diagnostic odyssey” and it can be a lot of stress for patients and their families,” explains Dr. Kishore Kumar , study co-author and clinical neurologist at Concord Hospital, Australia.

Although STR expansion disorders cannot be cured, faster diagnosis can help clinicians identify and treat complications associated with the disease much earlier. For example, problems with the cardiovascular system in Friedreich’s ataxia , associated with degenerative damage to the nervous system.

“The new test will revolutionize the diagnosis of these diseases. Now we can test all disorders simultaneously with a single DNA test and make a clear genetic diagnosis, helping patients avoid years of unnecessary muscle or nerve biopsies or risky treatments that suppress their immune systems,” says Dr. Kumar.

With just one DNA sample, derived from the patient’s blood, the test works through Nanopore sequencing technology to scan the genome for STR. The device, which uses Nanopore technology, is smaller and cheaper than standard tests, which the team hopes will make it easier to implement.

“Nanopore has reduced the size of a gene sequencing device from the size of a refrigerator to the size of a stapler and costs about $1,000 compared to the hundreds of thousands required for traditional DNA sequencing technologies,” concluded Dr. Deveson.

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