Children are a bundle of joy. Having one child at a time is amazing; however, having a set of twins is mind-blowing. Twins are a set of two individuals that were conceived at the same time.
In other words, twins are two people from the same pregnancy. You probably have wondered why a set of twins looks alike, and another set apparently has almost nothing in common aside from the fact that they shared the same womb simultaneously.
This article will help you figure things out. In the meantime, have you ever heard of monozygotic twins?
Monozygotic twins are twins who carry the same DNA (Deoxyribonucleic acids). DNA generally is what scientists call the carrier of genetic information. This means that what makes you unique as an individual is found in your DNA.
However, monozygotic twins have the same kind of DNA. Although most monozygotic twins carry the same type of DNA, they are never really the same. When it comes to identifying an individual through his/her personality, scientists have proved that there are two ways to do this.
These ways include Phenotypic typing and genotypic typing. Phenotypic typing concerns all traits that can be seen with the naked eye—for example, skin color, hair color, etc. Genotypic typing, on the other hand, concerns your genes.
How Are Monozygotic Twins Formed?
Generally, during conception, a single sperm cell is meant to fertilize only one egg. After fertilization has occurred, a zygote is formed.
This zygote can be described as the foundation of birth for any individual. After a couple of months, a baby is born from this zygote.
Back to the first stage of development after fertilization, once the zygote is formed, it proceeds to the second stage of development, the embryo stage.
It is at this embryo stage that you will determine whether you will have one child, a set of twins, or other multiple births.
In the case of twins, at the second stage of development, the embryo can suddenly split into two embryos.
You probably are wondering what happens to the cells in the embryo. Each of the cells of the embryo also will split.
This means that, although you originally had one cell during the embryo stage, if the embryo splits, each cell will split, giving you two of everything. Hence, each of these embryos can then begin two separate babies.
Recall that DNA was present in each cell that was initially formed. Hence, once the split occurs, the DNA of each of these cells also splits.
As a result, each of those babies carries the same type of DNA within their cells.
It is safe to say that monozygotic twins will have the same type of DNA. This is why monozygotic twins are known as Identical twins.
Monozygotic twins will most likely have the same phenotypic and genotypic appearances. Most monozygotic twins are of the same gender; they usually have the same of everything. For example, hair color, eye color, and so on are always the same.
However, some things will still be different about them, and scientists attribute this difference to the fact that they stayed in separate amniotic sacs. As such, this difference can result in some minor changes.
These minor changes are often used by parents to distinguish between monozygotic twins. According to research, monozygotic twins make up almost one-third of all twins.
Although all births have certain risks and pathological tendencies, when it comes to multiple births, then the pathological risks are significantly greater.
In other words, although it is great to have twins, certain complications may arise from their pregnancies.
Some of these complications include:
Twin-to-Twin Transfusion Syndrome (TTTS)
This condition is one of the rare complications that can occur in multiple pregnancies. This syndrome is most commonly seen in monozygotic pregnancies because, often, monozygotic twins share the same placenta.
TTTS occurs when there is an imbalance in the amount of blood shared between the babies. Most monozygotic twins share the same placenta and blood vessels that supply them with nutrients and oxygen.
Sometimes, due to unknown causes, one of the twins (often referred to as the donor twin) gives out much more blood carrying oxygen and nutrients than he/she receives from the other twin (often referred to as the recipient twin).
Once this occurs, the donor twin can risk suffering from inadequate blood supply, nutrient deficiency, stunted growth, or, in some worse cases, organ failure and possible death.
On the other hand, the recipient twin receives excess blood(much more than is needed), which will lead to the heart of the baby overworking itself, leading to several cardiac complications and teratologies.
Twin Reversed Arterial Perfusion (TRAP) Sequence
This is another rare medical complication that can occur in monozygotic twins. This condition is said to occur when the cardiac system of one of the twins is responsible for pumping blood to both children.
In this condition, the twin that ends up supplying blood to both of them is known as the ‘pump twin.’ Once this occurs, the pump twin’s heart becomes overworked (because it is doing the job for two).
On the other hand, the other twin that receives the supply without work (also known as the acardiac twin) will either have no heart or have one that is malformed.
Also, the acardiac twin may not develop completely, leading to the lack of hands, legs, or a head.
Twin Embolization Syndrome
This is another rare complication that often occurs following the death of one of the twins in vitro. The type and extent of damage done to the surviving twin depend on the gestational age of the twins.
If one of the twins dies at the early stage of the pregnancy, the other twin will suffer from atresia and tissue loss.
However, if any of the twins die towards the second trimester of the pregnancy because the heart is already formed, it will result in the other twin developing certain conditions, such as tissue infarction.
Once the tissues begin to break down, they form thromboplastic materials. These thromboplastic materials can enter the circulation of the other twin and, as such, result in disseminated intravascular coagulopathy.
These emboli can block the flow of some organs in the living twin’s body, including the kidneys, the heart, and the brain,, resulting in several complications.
Although the causes of these complications are not clear, some scientists have speculated that they can be a result of environmental and genetic conditions as well as lack of adequate drug(s).
In conclusion, monozygotic twins are babies born from the splitting of one embryo to form two separate embryos.
These sets of twins are seen to have the same DNA and, as such, have the same genotypic and phenotypic features. However, because they were formed in different amniotic sacs, they will have some other minor differences.
If you know you are having monozygotic twins, you must endeavor to follow your doctor’s instructions strictly.
