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6 Ways Restriction Digestion Is Revolutionising Genetic Testing

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Until a few decades ago, many medical professionals focused on the physiology and anatomy of the body to study diseases and find cures. However, since the completion of the Human Genome Project in 2003, healthcare workers are now quickly understanding where real answers lie – in our DNA.

And so, in recent years, genetics has undergone rapid and significant changes. Advances in technology and increased collaboration between scientists have led to a deeper understanding of the human genome and the genetic basis of disease. The field has expanded to encompass various applications, including personalised medicine, gene therapy, and genetic engineering. New tools and techniques, such as CRISPR-Cas9 gene editing and high-throughput sequencing, have revolutionised the field and opened up new avenues for research. As a result, genetics is at the forefront of many of today’s most exciting scientific breakthroughs. It is poised to make significant contributions to the future of medicine and biotechnology.

One such advancement comes from the principles of restriction digestion that has quickly revolutionised genetic testing. This technique involves cutting DNA molecules into smaller fragments at defined recognition sites. Due to its incredible specificity and highly efficient results, its applications are broadly diverse today.

Here are six ways it has already revolutionised genetic testing in molecular biology and genetic engineering.

DNA sequencing

DNA sequencing is a technique that allows scientists to isolate a patient’s DNA and create a series of letters that represent their genetic code. While this approach isn’t always practical since sequencing reagents are expensive and the human genome is large, by using restriction enzymes, researchers can cut out the region of interest and only get this section sequenced for analysis. Besides making the entire process cost-efficient, this also reduces the chances of error or getting ambiguous results since a smaller fragment is easier to sequence.

When a doctor or another medical professional interprets the sequencing results, they can identify any potential mutation in a patient’s DNA. This approach makes disease diagnosis quick and precise, allowing for better-targeted treatments.

SNP analysis

Single Nucleotide Polymorphisms (SNPS) are people’s most common genetic variations since they’re present in more than 1% of the population. The difference in the gene occurs in only a single base (or letter) and could be in the form of addition, deletion, or substitution. The subsequent mutation doesn’t always result in a disorder but can also be a silent alteration in the genome. However, if this mutation changes the genetic code for a particular protein, it may manifest into a medical condition. An example of this genetic variation is sickle cell anaemia –  a disease that results in low haemoglobin levels due to the abnormal shape of red cells. The “sickled” body of the blood cells is due to an SNP where base T gets replaced with A and forms a different amino acid.

Restriction digestion is beneficial for genetic testing of such diseases and other SNPs. Since these enzymes only form cuts at defined regions, they will only nick the DNA at the T-site or A, depending on which one gets used. This way, laboratory testing can quickly reveal whether a specific SNP is present in a patient’s sample.

Forensic analysis

Besides its use in medical diagnosis, restriction digestion has several applications in forensic genetic testing to analyse DNA evidence found at a crime scene. This technique can help investigators identify suspects or exclude individuals from a criminal investigation. By cleaving DNA at specific sites, restriction enzymes can create fragments of DNA that professionals can compare to known samples, such as those taken from a suspect or a DNA database. Additionally, restriction enzymes can enhance the sensitivity and accuracy of DNA analysis, especially when the sample size is small or degraded.

With restriction enzymes in forensic testing, the field of criminal investigation has reached new highs. Besides enabling the quick and accurate identification of perpetrators, it also helps exonerate the innocent.

Paternity tests

Another application of restriction digestion is determining an individual’s genetic or biological relations. Restriction enzymes are commonly used in paternity testing to determine whether a child is biologically related to a putative father. This process involves analysing the DNA profiles of the child, the mother, and the supposed father. Using restriction enzymes, the DNA gets cleaved at specific sites, resulting in smaller fragments of varying sizes. These sections are then compared with other suspected individuals to match and identify shared genetic markers. The more attributes that are common, the more likely it is that this individual is the child’s biological father.

Restriction digestion in paternity testing has made it a highly reliable and accurate method of determining biological relationships, with a very low probability of error.

Gene editing

Restriction enzymes and other molecular tools help introduce precise genetic changes into the DNA. As a result, gene editing has revolutionised the treatment of genetic diseases and other applications. For example, one of biotechnology’s most revolutionary inventions – human insulin, couldn’t have been possible without restricted digestion. Since molecular techniques are useless without precision and very vulnerable to contamination, the specificity of restriction enzymes mitigated several problems simultaneously. The gene responsible for creating insulin was isolated using a restriction enzyme and then inserted into a vector to make several copies.

Today, insulin is available in abundance only because of genetic engineering and restriction enzymes that made this invention possible. Since diabetes is a chronic illness and most patients depend on regular insulin intake, this discovery was a pinnacle of modern medicine.

Besides synthetically manufacturing insulin, restriction enzymes can edit genes to remove a defective or mutated gene. Once space gets created, foreign DNA without any abnormalities gets artificially inserted into the patient’s DNA to eliminate the possible risk of acquiring a genetic disorder.

DNA mapping

DNA mapping is a molecular technique that focuses on describing and locating the positions of all the genes in a human genome. It shows how close or far apart specific genes are, which makes it easy to identify possible associations between a mutation and a disorder. It also provides clues on how diseases get transmitted from parent to child and if more than one gene is responsible. With the help of restriction digestion, scientists can obtain structural information about an unknown DNA fragment. They do this by subjecting a DNA sample to several restriction enzymes and then analysing the resulting pieces of various sizes. Then the distance between each cleavage site is determined to estimate the size and structure of an unknown DNA sample.

Takeaway

The advancements in genetic testing and sequencing technologies have improved the healthcare industry and patient care. Due to this rapidly revolutionising field, healthcare practitioners now have a deeper understanding of the underlying causes of many diseases, leading to more accurate diagnoses, targeted treatments, and improved patient outcomes. Since their first use in genetic testing, restriction enzymes have come a long way, making the once-challenging analysis simpler, better, and faster.


Ellen Diamond, a psychology graduate from the University of Hertfordshire, has a keen interest in the fields of mental health, wellness, and lifestyle.

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