Robertsonian translocation is the most common form of chromosomal translocation in humans. It means that two chromosomes, the structures that make up a person’s DNA, join together in an abnormal way.
The condition does not necessarily cause any symptoms, but some people with it may face difficulties having a family. Read on to find out more.
Every person has a unique DNA code that exists inside the nucleus of every cell of their body. The DNA tells each cell how to divide and multiply.
DNA exists in thread-like structures that scientists call chromosomes.
These threads have two sections called the ‘p arm’ and the ‘q arm.’ The ‘p arm’ is also known as the ‘short arm’ while the ‘q arm’ is known as the ‘long arm’.
The two chromosomal arms vary in length and meet at a point known as the centromere.
An acrocentric chromosome is one where the centromere is very close to one end of the ‘thread.’ This makes one of the arms very short. Chromosomes
In Robertsonian translocation, the two long arms of two separate acrocentric chromosomes fuse to create one chromosome. The short arms are usually lost. This is sometimes called centric-fusion translocation.
Chromosomes 13 and 14, 13 and 21, or 21 and 22 fusing are the most common forms of Robertsonian translocation.
Robertsonian translocation does not always cause health problems, and many people will never know they have it. They will usually live as long and healthy a life as their peers, providing there are no other health complications.
That said, in some cases, when Robertsonian translocation results in people having extra genetic material in their bodies, the translocation can lead to genetic disorders.
These include the following:
Around 1 in 16,000 babies are born with trisomy 13. It is also called Patau syndrome.
Trisomy 13 usually occurs when people have three, rather than two, copies of chromosome 13. It can also happen when chromosome 13 fuses to another chromosome.
Trisomy 13 can cause physical abnormalities, such as extra fingers or toes, an opening in the lip, or cleft lip, or an opening in the roof of the mouth, or cleft palate.
Other symptoms include:
- intellectual disability
- heart defects
- brain or spinal cord abnormalities
- small or poorly developed eyes
- weak muscles
Most babies born with trisomy 13 die within the first days or weeks of life. Only 5–10% of children with the condition will live past their first year.
Translocation Down syndrome
Around 5,300 babies are born with Down syndrome in the United States each year. Down syndrome occurs in around 1 in 800 newborns.
Most cases are caused by having three rather than two copies of chromosome 21. Experts call this trisomy 21.
Sometimes, Down syndrome occurs when part of chromosome 21 fuses with another chromosome. Scientists call this translocation Down syndrome, which accounts for just 3–4% of cases.
The condition results in mild to moderate intellectual disability and a characteristic facial appearance. Heart defects affect around 50% or less of people with Down syndrome. Some can also experience digestive abnormalities.
Robertsonian translocation is a genetic disorder. People inherit it from their parents with the mother or father passing it to a child in their genes.
In most cases, Robertsonian translocation does not cause any health problems or require treatment.
People who carry the abnormality, however, may pass it on to their children. Aspiring parents may wish to seek genetic counseling before starting a family.
The genetic counselor will be able to talk about specific risks and benefits to help the would-be parents make a decision.
Many people with Robertsonian translocation have healthy children. The condition can, however, impact on their chances of having a family.
Women with the translocation may find it difficult to get pregnant. They also have a higher chance of having a miscarriage than those without Robertsonian translocation.
As the translocation affects a person’s genes, those with the condition may have children with a genetic disorder as well.
Many people with a Robertsonian translocation will be unaware that they have it. It does not usually impact health or wellbeing, although it can pose problems when having a family.
In some cases, the translocation can result in a genetic disorder, such as trisomy 13 or Down syndrome.
Babies born with trisomy 13 usually die within the first days or weeks of life.
Children with Down syndrome tend to experience health complications. These include heart defects and an increased risk of infection, as well as problems with their respiratory system, vision, and hearing.
With the right medical care and support, people with Down syndrome live long and healthy lives. Their life expectancy is onlyslightly shorter than those without the condition.
Robertsonian translocation is a genetic abnormality. It occurs when two acrocentric chromosomes fuse.
Most people with Robertson translocation do not know they have it. They live normal, healthy lives, though they may have concerns when starting a family.
In some cases, Robertsonian translocation can result in a congenital genetic disorder, such as trisomy 13 or Down syndrome.