Understanding Stats in Genetics
Genetic testing can reveal powerful insights about your health. But behind every result is a foundation of statistics that helps us interpret your DNA accurately.
Genetic testing can reveal powerful insights about your health. But behind every result is a foundation of statistics that helps us interpret your DNA accurately.
Genetic testing doesn’t just say “yes” or “no”, it estimates probabilities. We look at patterns in your DNA and compare them to scientific data from thousands of people to understand what’s typical, what’s rare, and what might affect your health. Below is a simple guide to help you understand what these numbers really mean.
Genetic test results can feel complex, these six key terms explain what the numbers mean and how reliable your result is. Test statistics can vary depending on the condition being screened for and the population being tested, and when you screen for a wider range of conditions, such as with advanced genetic testing, the predictive value for rarer findings may differ. Our team will help you interpret your genetic tests in the right clinical context.
Prevalence refers to how many people in a given population carry the gene variant or have the condition. The more common it is, the more it affects the PPV and NPV of the test. In short, prevalence helps shape how useful a test result will be in the real world.
A test with high sensitivity correctly identifies most people who actually carry the gene variant. In other words, the higher the sensitivity, the more likely it is that if you do have the variant, the test will detect it.
A test with high specificity correctly identifies most people who do not carry the gene variant. In other words, the higher the specificity, the more likely it is that if you don’t have the variant, the test will report a negative result – and avoid a false alarm.
Positive Predictive Value (PPV) tells you how likely it is that you actually have the condition or variant if your test result comes back positive. A high PPV means that most people who test positive truly carry the variant. This value depends not just on the test's accuracy, but also how common the condition is in the population being tested.
Negative Predictive Value (NPV) tells you how likely it is that you don’t have the condition or variant if your test result is negative. A high NPV means that most people who test negative truly don’t carry the variant. Just like PPV, this depends on the test’s accuracy and how rare or common the condition is.
Test accuracy shows the overall chance that the test result, positive or negative, is correct. It combines both sensitivity and specificity to give you a big-picture view of how reliable the test is.
Learn about how genetic test accuracy varies based on Sensitivity, Specificity, PPV, NPV and Prevalence.
At Jeen, we focus on health, not hair colour. Our genetic testing uses 50x sequencing depth (NGS) for greater accuracy and confidence in detecting inherited conditions.
DNA is broken into small fragments, sequenced, and computationally assemble into the full genome.
Sequencing depth is how many times your DNA is read. Higher depth = more accurate results, lower depth = risk of missed mutations.
Larger genomes (like humans) need more sequencing reads. That’s why high-depth testing matters-it ensures nothing is missed.
Not all genetic tests are created equal. At Jeen, we use 50x sequencing coverage, which means each section of your DNA is read around 50 times. Here’s why it makes a difference:
Bigger genome → more data needed
Higher depth → better accuracy
Balance cost vs. detail!
Have questions? We’re here to help. Genetic testing can feel overwhelming, but it doesn’t have to be. Our genetic counsellors are here to walk you through your options, explain the science in plain English, and help you decide if testing is right for you.
Sensitivity and specificity help you understand how reliable a test is. A test with high sensitivity catches more true positives, and one with high specificity avoids false alarms. Together, they help ensure your results are trustworthy.
Not quite. Even highly accurate tests need interpretation. A genetic counsellor helps explain what your result means for you and your family and whether you need any follow-up or additional screening.
These metrics help determine a test's accuracy. High sensitivity ensures most carriers are identified, while high specificity ensures non-carriers aren't misdiagnosed. Together, they provide a comprehensive view of a test's reliability.
Sensitivity measures how well a test identifies true positives among all who have the condition, while PPV assesses the likelihood that a positive test result is a true positive. Sensitivity is intrinsic to the test, whereas PPV is influenced by the condition's prevalence in the population.
Several things can influence genetic test accuracy, including how common the gene variant is in the population (prevalence), the quality of the lab, and even how the sample was collected. That’s why expert-designed tests and genetic counselling matter.
Test statistics like sensitivity and PPV can vary depending on the population being tested, the condition being screened for, and how the test is used. Context matters! Jeen’s team of clinical geneticists, genetic counsellors, and midwives will explain your results in a way that fits your unique case.
Yes. A test designed to catch all potential cases (high sensitivity) might also capture individuals without the condition, leading to false positives and thus lower specificity. Balancing both metrics is crucial for accurate testing.
Yes. And it’s a key part of your journey with Jeen. Our genetic counsellors are here to help you understand what your results mean and guide you through everything, including terms like sensitivity and specificity. You’ll have a counselling session before your test to explain what we’re looking for and what the results could mean. If your result shows something unusual, we’ll contact you and arrange a follow-up session. Even if your results are normal, you're always welcome to book another session if you'd like to talk them through with our team.
The statistics and clinical claims on this page are supported by the following authoritative sources.
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