Chromosomes are like the blueprints of our body – they carry the genetic information that determines how we grow, develop and function. Each person usually has 46 chromosomes, which are divided into 23 pairs. These are found in almost every cell and consist of DNA, a kind of molecular code. However, sometimes there are changes in the chromosomes – too many, too few or errors in the structure – which can cause diseases. Laboratory medicine in Germany plays a decisive role in recognizing and understanding such changes.

What are chromosomes?

Chromosomes are thread-like structures in the cell nucleus that contain our genes. We get half of them from our mother, the other half from our father. Of the 23 pairs, 22 are so-called autosomes – they are the same in men and women. The 23rd pair are the sex chromosomes: XX in women, XY in men. These chromosomes not only control whether we have brown eyes or blonde hair, but also how our body works. If something is wrong with them – for example, a chromosome is missing or a piece has broken off – developmental disorders, malformations or diseases such as Down’s syndrome can occur.

Why are chromosomes examined?

The examination of chromosomes, also known as chromosome analysis or cytogenetics, helps to identify genetic problems. This is important, for example, if a child is born with unclear malformations, couples are unable to have children or certain diseases are common in the family. Chromosomes can also be tested during pregnancy to ensure that the baby is healthy. In Germany, laboratory medicine is a leader in this field because it uses state-of-the-art techniques to clarify such issues.

What tests are available?

German laboratories use various methods to analyze chromosomes. Here are the most important ones:

1. Karyogram: This is the classic test. Cells – usually from blood, sometimes from amniotic fluid – are cultivated in the laboratory. The chromosomes are then stained and examined under a microscope. This allows you to see whether the number is correct (usually 46) or whether a chromosome is damaged. In Down’s syndrome, for example, there is an extra chromosome 21 – this is called trisomy 21.
   
2. FISH (fluorescence in situ hybridization): This method is more accurate and faster than the karyogram. It uses fluorescent dyes that bind to specific chromosome sites. This allows a targeted search for known errors, such as small losses or duplications associated with diseases such as DiGeorge syndrome.
   
3. Array-CGH (chromosome microarray): This goes even deeper. This technique compares a patient’s DNA with a healthy reference DNA. It finds tiny changes that are not visible with a microscope – so-called microdeletions or duplications. This is particularly useful when doctors don’t know exactly what they are looking for.
   
4. Molecular genetics: Sometimes chromosome analysis is not enough and the DNA is examined directly for genetic defects. This overlaps with chromosome diagnostics if larger sections are affected.

How does this work in Germany?

In Germany, specialized laboratories carry out these tests – often in hospitals, university clinics or private institutions. Medical technologists for laboratory medicine (MTL) and specialists in human genetics work hand in hand here. A blood sample or a swab is usually sufficient; in the case of pregnant women, amniotic fluid or a piece of placenta is sometimes taken. The samples are then elaborately prepared and analyzed in the laboratory. The results are sent to the doctor, who discusses them with the family.

Laboratory medicine in Germany must adhere to strict rules – such as the IVDR (In Vitro Diagnostics Regulation), which ensures that tests are reliable. There are also quality controls to ensure that the results are accurate. This is important because an error could have far-reaching consequences, such as an incorrect diagnosis or unnecessary concern.

Why is this important?

Chromosome tests can change lives. They help to detect diseases at an early stage – for example trisomies such as Down’s syndrome before birth. For parents planning children, they can clarify whether genetic risks exist. And in the case of unclear symptoms – such as developmental delays in children – they often provide the answer as to why something is wrong. This allows targeted therapies to be used or families to be advised.

At the same time, this is where laboratory medicine shows its strength: it combines science with practice. Without these tests, many diagnoses would be a guessing game. This is particularly relevant in Germany because the healthcare system relies on precision and patients expect a high standard.

Conclusion

Chromosomes are the key to our biology, and laboratory medicine in Germany ensures that we understand them. Using methods such as karyograms, FISH or array CGH, laboratories uncover what is going on in our cells – precisely, safely and scientifically. This not only helps individuals, but also medicine as a whole to become better. Whether for pregnant women, children or people with unclear complaints: This work makes a difference – quietly, but vitally.

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Gender note. The personal designations used in this text always refer equally to female, male and diverse persons. Double/triple references and gendered designations are avoided for the sake of better readability ected.