We all have our genetic information stored inside the cells of our bodies. It's like books in a big library. We call these books chromosomes. We grow up with half from our mother and half from our father. But imagine, sometimes two pages of these books get torn, and a page from one book gets stuck to the other, and a page from the other book gets stuck to this book. That's how we call translocation in medicine when parts of two chromosomes break off and switch to each other. Don't be scared when you hear this name. Many people can have this, and they may not even know it. Let's see what it really is.
What is this genetic change called Translocation?
Simply put, a translocation is a change in the structure of chromosomes. This occurs when a piece of one chromosome breaks off and attaches to a different chromosome. Sometimes, the broken piece of the second chromosome can also attach to the first.
Inside the nucleus of each of our cells, there are 23 pairs of chromosomes. That's a total of 46 chromosomes. Of these, 22 pairs control all other characteristics of the body (autosomes), while the last pair determines our gender (X and Y chromosomes).
Translocation can be divided into two main types:
1. Reciprocal Translocation: This is when parts of two different chromosomes are exchanged. Imagine a piece of chromosome 7 being transferred to chromosome 21, and a piece of chromosome 21 being transferred to chromosome 7.
2. Robertsonian Translocation: This is when one chromosome completely attaches to another chromosome.
Now there is another important thing. If these parts are swapped, but no genetic information is lost or gained, we call it a Balanced Translocation . A person with this usually does not have any health problems. However, if some genetic information is lost or gained due to this swap, we call it an Unbalanced Translocation . That is when various health problems start to arise.
Is it just translocation? Other changes that can occur in chromosomes
In addition to translocation, there are several other changes that can occur in the structure of chromosomes. These can also disrupt the protein production process in our body and affect the functioning of cells and tissues. Let's take a look at what they are.
| Type of change | What simply happens |
|---|---|
| Deletion | A part of a chromosome breaks off and is removed. This can result in the loss of several or hundreds of important genes in the body. |
| Duplication | A part of a chromosome is abnormally copied twice, providing more genetic information. |
| Inversion (turning a part the other way around) | A chromosome breaks in two places, then the part turns around and reattaches. |
| Other complex changes | More complex variations can occur, such as isochromosomes (chromosomes with two identical arms) and ring chromosomes (chromosomes shaped like a ring). |
When is this translocation important?
There are millions of cells in our body. If just one of these cells undergoes this kind of change, it won't have much of an impact. That cell will probably die after a while.
However, this translocation is only really serious and important if it occurs in the mother's egg (ovum), the father's sperm (sperm), or the first cell formed by the union of the two (zygote).
Imagine, that single cell then divides and divides to form a complete child. That means that every cell in the child's body has that translocation. That's when various diseases occur due to the increase or decrease in genetic information.
Sometimes this change happens after the baby is conceived. Then some cells in the body may be normal and some cells may have the translocation. We call this Mosaicism .
Let's look at a real-life example.
To understand this better, let's take an example. Imagine there is a person, let's call him Sunil. Sunil does not have any disease, he is healthy. But if we check his genes, he has a balanced translocation between his 7th and 21st chromosomes. That means that parts have been swapped, but he has all the necessary genetic information in his body. Therefore, he does not have any problems.
The problem comes when a child is made. When the sperm is made in Sunil's body, the chromosome pairs separate. Here, unfortunately, some sperm can carry the 7th chromosome with the piece of the 21st attached instead of the normal 7th chromosome. At the same time, the normal 21st chromosome can also go to that sperm.
Now, what happens if this sperm unites with a healthy egg and a child is born? The mother receives one 21st chromosome. The father (Sunil) receives both the normal 21st chromosome and the part of the 21st chromosome attached to chromosome 7. Then, the child's cells have three pieces of genetic information related to chromosome 21. That is what we call Down syndrome .
Now do you understand how someone with a balanced translocation can have a child with an unbalanced translocation, even if they have no symptoms?
Diseases that can be caused by translocation
There are several main medical conditions that can be caused by translocation.
| Medical condition | Frequently associated chromosomes and description |
|---|---|
| Down syndrome | This condition is most often caused by the presence of three copies of chromosome 21 instead of two (Trisomy 21). However, a small percentage of cases are caused by a translocation. The most common is an exchange between chromosomes 14 and 21. These children can have complications in the heart, digestive tract, and spine. |
| Chronic Myelogenous Leukemia (CML) | This is a type of blood cancer. It is caused by a translocation between chromosomes 9 and 22. The new 22nd chromosome that is formed as a result is called the Philadelphia chromosome . This produces an abnormal enzyme that causes cancer cells to grow uncontrollably. |
| Lymphoma and other types of leukemia | Translocations between other chromosomes, such as chromosomes 8 and 11, can also cause various types of leukemia and lymphoma. |
Take-Home Message
- A translocation may be harmless (balanced), or it may cause serious diseases (unbalanced).
- If you have a balanced translocation, you can live a healthy life. The only problems you may have are when you have children.
- This condition can be inherited from parents, or it can develop newly at the time of conception.
- There is no "cure" for a translocation, because it is present in every cell in the body. However, the diseases that result from it can be treated.
- This is not a contagious disease. You can socialize with others, have sex, and donate blood without any fear.
- If someone in your family has a genetic disease, or if you have any doubts or questions about this, the best thing to do is to see your doctor or physician and talk about it.
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