Understanding genetic testing: The difference between DNA and genes explained simply

DNA and gene compared directly

Before we go into the details, an initial overview is helpful. The following table concisely summarizes the most important distinguishing features.

From DNA to gene to protein

Your body operates according to a clear hierarchy. DNA forms the foundation. Individual genes are read from it. These genes, in turn, control the production of proteins—and proteins ultimately determine what your body looks like and how it functions.

What is DNA?

DNA stands for deoxyribonucleic acid. It is the chemical substance stored in nearly every cell of your body and contains all genetic information. DNA is the foundation of all life—it determines which proteins your body produces and, consequently, how your body is built and how its metabolism functions.

The double helix as a storage medium

DNA consists of two long strands that wind around each other like a spiral staircase—a double helix. Each strand is a chain of chemical building blocks called nucleotides. There are four different nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G). The sequence of these four letters forms the genetic code. A single human cell contains about two meters of DNA—an almost unimaginable amount of information when multiplied across the approximately 37 trillion cells in the body.

The two strands of DNA are complementary. Adenine always binds to thymine, and cytosine always binds to guanine. This pairing rule allows DNA to replicate during cell division. Each of the two strands serves as a template for a new, matching strand. This reliably passes genetic information on to daughter cells.

Chromosomes: How DNA is packaged

The DNA in your body would be far too long to fit inside a cell as a single strand. That is why it is compactly packaged. Together with proteins called histones, DNA winds into complex structures known as chromosomes. Most human body cells contain 46 chromosomes—23 pairs. Each pair consists of one chromosome inherited from the mother and one inherited from the father.

The first 22 pairs are called autosomes. The 23rd pair consists of the sex chromosomes—two X chromosomes in women and one X and one Y chromosome in men. The entire DNA of all the chromosomes together forms the human genome. The Human Genome Project, which ran from 1990 to 2003, deciphered this genome for the first time to a large extent.

What is a gene?

A gene is a defined segment of DNA that forms a specific functional unit. Geneticists define a gene as the smallest unit of heredity that carries specific information. In most cases, this information consists of the instructions for building a protein. Some genes, however, code for functional RNA molecules that perform tasks in the cell themselves.

From the DNA sequence to the functional molecule

The process by which the information in a gene is converted into a function is called gene expression. First, the DNA is transcribed into messenger RNA (mRNA). This mRNA leaves the cell nucleus and travels to the ribosomes, the cell’s protein factories. There, the sequence of bases is translated into a sequence of amino acids—the resulting molecule is a protein.

A single gene can consist of several thousand base pairs. Human DNA is estimated to contain 20,000 to 25,000 protein-coding genes. That may sound like very few compared with the three billion base pairs, but these genes are responsible for the entire complex biochemistry of your body. A gene can also be read in different ways, allowing several different protein variants to be produced from a single gene.

Regulatory regions and non-coding DNA

Not every segment of DNA is a gene. In fact, only about 1 to 2 percent of human DNA directly codes for proteins. For a long time, the much larger portion of DNA was known as “junk DNA.” Today we know that these non-coding segments contain important control and regulatory elements. They determine when a gene becomes active and how strongly it is read.

These regulatory regions are just as relevant to genetic testing as the genes themselves. A change in a gene’s promoter region—the control switch directly before the gene—can have the same effect as a change within the gene. Some genetic tests therefore specifically analyze these regulatory regions to understand how active a particular gene is.

DNA vs. gene: The key differences

The crucial difference between DNA and a gene can be illustrated with a simple analogy: DNA is the entire cookbook, while a gene is a single recipe in it. The cookbook contains all the recipes you will ever need. The individual recipe, however, tells you which ingredients you need for a particular dish and how to prepare it.

Quantity vs. quality

DNA encompasses the quantitative whole. It is long, extensive, and contains large non-coding regions in addition to genes. A gene, by contrast, is qualitatively defined: it has a specific start and end position on the DNA and a clearly assigned function. When researchers speak of a gene, they do not simply mean any arbitrary section of DNA, but a biologically defined unit with evidence demonstrating its function.

Structure vs. function

Another important difference lies in the relationship between structure and function. DNA as a whole is primarily a storage medium. Its physical structure—the double helix—is optimized to store and replicate information stably and accurately. A gene, by contrast, is primarily a functional unit. Its sequence determines which protein is produced and, consequently, which biochemical reaction takes place in the cell.

Specifically, this means that if you have your DNA sequenced, you obtain the sequence of all bases. That amounts to enormous quantities of data. When you take a genetic test, specific genes or variants within them are analyzed selectively. A genetic test does not provide information about your entire DNA; instead, it focuses on the sections relevant to your question.

All cells are the same—gene expression differs

Every body cell—whether a skin cell, nerve cell, or liver cell—contains identical DNA. Nevertheless, these cells look completely different and perform different tasks. The reason lies in gene expression. Not all genes are active in every cell. A liver cell reads different genes than a nerve cell. The DNA remains the same; the genes being used change.

This distinction is a central point for understanding genetic tests. A genetic test analyzes the underlying DNA sequence. In other words, it tells you which variant of a gene you carry. However, it does not necessarily tell you how active that gene currently is in a particular tissue. For many health-related questions, sequence information is nevertheless sufficient because certain variants are robustly associated with traits or risks.

What is a genetic test and how does it work?

A genetic test is a laboratory analysis that specifically examines certain sections of your DNA. The goal is to identify variants—also called mutations or polymorphisms—that are associated with particular traits, metabolic pathways, or health risks. A genetic test generally does not sequence your entire genome but focuses on predefined genes or genetic markers.

The sample: saliva, blood, or swab

The basis of every genetic test is a biological sample containing human DNA. The most common types of samples are saliva, a drop of blood, or a cheek swab. Saliva tests are particularly common because sample collection is simple and non-invasive. Your saliva contains enough cells from the lining of the mouth to isolate DNA. The quality of the DNA is entirely sufficient for most analysis methods.

In the laboratory, DNA is extracted from the sample. This means the cells are broken open, proteins and fats are removed, and the pure DNA is isolated. The DNA is then amplified to obtain enough material for analysis. This step is called amplification and is usually carried out using a polymerase chain reaction (PCR).

SNPs: The letter changes that can change everything

Most consumer genetic tests analyze so-called SNPs (single nucleotide polymorphisms, pronounced “snips”). An SNP is a location in DNA where the sequence of letters differs between people. For example, a guanine (G) may appear where you have an adenine (A). These single-letter differences are the most common form of genetic variation in humans.

More than 600 million SNPs are known in the human genome (National Center for Biotechnology Information, dbSNP). Not every SNP affects health. Many are located in non-coding regions or do not alter the protein. Other SNPs, however, can change the function of an enzyme, affect how a nutrient is processed, or modify the risk of certain diseases. A genetic test specifically examines those SNPs for which scientific studies have demonstrated a verifiable association.

Genotyping vs. sequencing

There are two basic analysis methods that should be distinguished. Genotyping examines which variants are present at predefined locations in the genome. It is cost-effective and provides sufficient data for most health and metabolism-related questions. Sequencing, on the other hand, actually reads the sequence of DNA letters—either for individual genes (panel sequencing), the entire exome (exome sequencing), or the genome (whole-genome sequencing).

Most direct-to-consumer genetic tests use genotyping chips. These chips contain millions of probes that simultaneously test for thousands of SNPs. The result is a dataset containing your genotypes at these specific positions. For questions such as “How do I metabolize vitamin D?” or “Am I genetically lactose intolerant?” this method is scientifically well established and proven in practice.

Why does the difference matter for your health?

Understanding the difference between DNA and a gene is not an academic quibble. It has direct implications for how you interpret genetic tests and what expectations you have of the results. Once you know that a genetic test analyzes specific gene segments rather than your entire DNA, it becomes clear: The test can only answer the questions it was designed to address.

Metabolic genetics: Why the same coffee affects everyone differently

Caffeine metabolism is an illustrative example. The CYP1A2 enzyme is produced by the gene of the same name, CYP1A2. People with a certain variant of this gene produce a faster-acting enzyme. They break down caffeine more quickly and can often tolerate more coffee. People with a slower variant feel the effects of coffee for longer and more intensely—and may have an increased cardiovascular risk with high consumption. A genetic test can identify this variant. However, it cannot tell you exactly how much caffeine you are metabolizing today, because lifestyle, duration of intake, and other genes also influence this.

Nutrigenetics: How your genes influence your nutrient requirements

Nutrigenetics explores the interplay between genes and nutrition. For example, the vitamin D receptor gene (VDR) influences how efficiently your body absorbs vitamin D from food or sunlight and converts it into its active form. People with certain VDR variants may need higher intake levels to achieve the same blood concentration. According to the German Nutrition Society (DGE), around 30 percent of adults in Germany have insufficient vitamin D status. Genetics plays a decisive role for some of them.

Another example is the MTHFR gene, which codes for an enzyme that activates folate (vitamin B9). A common variant reduces the enzyme’s activity by 30 to 40 percent. People with this variant may benefit more from already activated folate (5-MTHF) in dietary supplements. A genetic test reveals this predisposition and enables a more targeted nutrient strategy.

Pharmacogenetics: How genes control medication response

Pharmacogenetics examines how genetic variants influence the effects and tolerability of medications. The cytochrome P450 enzyme system, consisting of several genes such as CYP2D6, CYP2C19, and CYP3A4, is responsible for breaking down most medications. Depending on the genetic variant, a person may be a slow, normal, or ultrarapid metabolizer. For certain psychotropic drugs, blood thinners, or stomach-protection medications, this has direct clinical consequences. The German Medical Association’s Drug Commission (AkdÄ) now recommends genetic testing before prescribing certain medications.

It is important to remember that a genetic test shows your genetic predisposition. It does not replace a doctor’s decision regarding medication and dosage. However, it can provide valuable additional information that may be considered in discussions with your doctor.

How mybody® applies the criteria

Once the basics are clear—DNA as the carrier of genetic information, genes as functional units, and genetic tests as targeted analyses—the question arises: How can you recognize a reputable provider? The following criteria will help you assess them. We will then show you how mybody® (MYBODY Lab GmbH) meets these standards.

Quality criteria for genetic tests at a glance

mybody® applies these criteria with an interdisciplinary team of specialists. The evaluation is carried out in an ISO-certified laboratory in Germany. All samples are handled pseudonymously, meaning that the DNA data cannot be directly linked to your name. Data transmission is SSL-encrypted. mybody® products have been offered to consumers since 2022; the company has been active since 2016 and has more than 11,000 users.

The specialist team includes experts in nutrigenetics, microbiome and gut science, blood analysis interpretation, nutritional science, and laboratory diagnostics. Every report is professionally reviewed before it is made available to you. The content on the health portal is continuously updated to reflect new scientific findings.

Which test is right for which goal?

Not every test is suitable for every question. The decision depends on whether you want to clarify a specific predisposition or obtain a comprehensive picture of your health.

A DNA test alone provides genetic predispositions. It tells you which variants you carry. A blood test alone shows you the current state of your body—for example, your blood vitamin D level. However, it does not tell you whether your low level is due to insufficient intake or genetically reduced utilization.

The combination of both provides more meaningful insights. If the blood test shows a deficiency and the DNA test simultaneously reveals a predisposition to reduced activation, you know that a normal intake may not be sufficient for you. You may need either higher doses or a different form of the nutrient. This combination of phenotype (blood value) and genotype (genetic predisposition) is known in technical terminology as multimodal analysis.

For purely informational questions such as “Am I genetically lactose intolerant?” or “How do I metabolize caffeine?”, a targeted DNA test is entirely sufficient. For a holistic nutrition and health strategy, combining DNA analysis with a blood panel provides significantly more meaningful insights. mybody®’s VitalCheck Complete was developed specifically for this combined approach.

Limitations of Genetic Tests

A genetic test is a powerful tool, but not a cure-all. To interpret the results correctly, you need to understand what a test can—and cannot—do.

Predisposition is not destiny

The most important limitation lies in the nature of genetic information. A genetic test shows predispositions. It does not show whether a disease will actually develop. Most diseases are multifactorial, meaning that genes, lifestyle, environment, and chance all interact. An increased genetic risk for diabetes does not mean that you will develop diabetes. It means that your lifestyle plays a greater role than it does for someone without this predisposition.

Not all genes are known

Although science has largely mapped the human genome, the function of many genes and variants remains unclear. A genetic test analyzes the genes for which evidence currently exists. However, there are regions of the genome whose significance will only be understood in the coming years. A negative result—that is, the absence of a known risk variant—does not completely rule out a risk.

A genetic test does not replace a medical diagnosis

A genetic test is not a medical diagnostic procedure. It provides information that can be valuable when discussed with medical professionals. In the event of health complaints or when assessing disease risks, medical advice remains the gold standard. The test does not replace a doctor’s visit, a clinical blood test, or diagnostic imaging.

Conclusion

The difference between DNA and a gene is fundamental to understanding modern health analyses. DNA is the complete repository of your genetic information—long, complex, and identical in every cell of your body. A gene is a specific, functional section of that DNA that carries a particular set of instructions for your body. A genetic test specifically analyzes these sections to reveal predispositions related to metabolism, nutrient requirements, and health characteristics.

If you are interested in a genetic test, pay attention to laboratory certification, data privacy, and scientific validity. Reputable providers such as mybody® (MYBODY Lab GmbH) work with certified German laboratories, pseudonymize samples, and clearly distinguish predispositions from diagnoses. Combining DNA analysis with a blood test gives you the most informative picture—genes show potential, while blood values show current status.

Our specific recommendation: Start with VitalCheck Complete if you are looking for a comprehensive understanding of your genetic predisposition and current nutrient status. The test combines DNA genotyping with blood analysis and provides you with a comprehensive, professionally reviewed report.

Frequently asked questions

Sources

1. National Human Genome Research Institute (NHGRI). Facts about the Human Genome Project. genome.gov
2. National Center for Biotechnology Information (NCBI). dbSNP Database. ncbi.nlm.nih.gov/snp
3. German Nutrition Society (DGE). Reference Values for Nutrient Intake: Vitamin D. dge.de
4. Drugs Commission of the German Medical Association (AkdÄ). Pharmacogenetics – A Guide for Clinical Practice. akdae.de
5. Robert Koch Institute (RKI). Study on the Health of Adults in Germany (DEGS1) – Vitamin D. rki.de
6. Federal Ministry of Education and Research (BMBF). Human Genome Research in Germany. bmbf.de
7. Regulation (EU) 2016/679 (GDPR). General Data Protection Regulation. eur-lex.europa.eu

The medical and scientific statements in this article are based on the sources cited [1]–[7]. Statistics on vitamin D status refer to the DGE reference values and RKI data [3][5]. Information about mybody® products (prices, processing times, sample types) is taken from the official product pages on mybody-x.com and should be verified there before publication.

mybody® Editorial & Expert Team

Nutrigenetics Laboratory Diagnostics Nutritional Science Microbiome Blood Analysis

This article was researched and written by the mybody® editorial and expert team. Our content is based on the latest scientific knowledge and is regularly updated. Learn more about our team and quality standards on the authors’ page.

Published: July 27, 2026 · Last updated: July 27, 2026

Note: The content of this article is for informational purposes only and does not constitute medical advice or a diagnosis. If you have health concerns or questions about disease risks, please consult a doctor.