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Resource
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4 mins min read
Published:
08/10/2025
Advanced genetic tests have revolutionized the way doctors can diagnose and understand complex diseases. Unlike older tests that look at just one gene at a time, these new tests can look at your entire genetic code. Here’s a detailed look at the different types:
1. Whole Exome Sequencing (WES)
What It Is: This test looks at all the parts of your genes that actually make proteins—called exons—which are just 1–2% of your DNA but where most disease-causing changes happen.
Why It’s Useful: WES is particularly useful when symptoms don’t point to one clear diagnosis, and earlier tests didn’t find answers. Plus, the results can be checked again later as scientists discover more about genes and diseases, which is especially helpful for rare or undiagnosed conditions.
2. Whole Genome Sequencing (WGS)
What It Is: WGS reads the entirety of your DNA, covering both the coding (exons) and non-coding regions. This test provides an all-encompassing view of your genetic code.
Why It’s Useful: Because it looks at everything, WGS can find all kinds of mutations, including big changes like missing or extra chunks of DNA. This test is useful when doctors strongly suspect a genetic cause but WES hasn’t found it. Sometimes the abnormality lies in those non-coding areas affecting gene control.
3. Targeted Gene Panel Testing
What It Is: Instead of scanning the whole genome, this approach sequences a select group of genes that are known to be associated with a particular condition or set of conditions.
Why It’s Useful: Gene panels are efficient when there is a strong clinical suspicion of a particular disorder. For example, if symptoms point toward a neuromuscular disorder, a panel might include all the genes known to be involved in that spectrum of diseases. Its quicker and cheaper compared to broader tests like WES or WGS, while still providing meaningful, actionable results.
4. Chromosomal Microarray Analysis (CMA)
What It Is: CMA does not sequence DNA in the conventional sense but instead assesses the genome for copy number variations—sections of the genome that are duplicated or deleted. It offers a high-resolution scan of the chromosomal structure.
Why It’s Useful: CMA is particularly effective in identifying larger structural changes that might be missed by sequencing-based methods. This test is frequently used to diagnose developmental disorders or congenital anomalies, where the issue might be due to an abnormal number of gene copies rather than a subtle mutation within a gene.
5. RNA Sequencing and Transcriptome Analysis
What It Is: Instead of looking at DNA, this test studies RNA—the molecules that carry instructions from DNA to make proteins. It shows which genes are active and how they are expressed in different tissues.
Why It’s Useful: Sometimes DNA looks normal, but RNA tests reveal problems with how genes are turned on or off, which can explain symptoms.
6. Epigenetic Testing
What It Is: Epigenetic tests examine chemical modifications on your DNA (like DNA methylation patterns) that affect gene expression without altering the underlying sequence.
Why It’s Useful: Epigenetic regulation plays a significant role in health and disease. Abnormal methylation patterns, for instance, can contribute to disorders even when the DNA sequence is normal. These tests can therefore help unravel conditions where environmental factors might influence gene behaviour alongside genetic predispositions.
Choosing the Right Test: Which test is best depends on your unique situation—your symptoms, medical history, and any previous testing. Genetic counsellors and specialists help decide the right test or combination of tests to give you the best chance at a clear diagnosis.
By using these advanced tests, doctors can get deeper insights into your genetics, leading to more accurate diagnoses and treatments tailored for you. The world of genomic medicine is constantly advancing, offering hope and new possibilities for people with rare or undiagnosed conditions.