If your baby has Saethre-Chotzen syndrome, the shape of his or her head will not change on its own. [Doctor-approved]

What parents need to know about Saethre-Chotzen syndrome

When you look at a newborn baby’s head,
have you ever felt something like, “The shape of the baby’s head is strange,” or “It will stabilize eventually?”

Correct your baby’s head position while he or she is still a baby. If the pressure in the womb during birth caused the head to change shape, time may help.

However, there are cases where the condition does not resolve. This is when the cause is a disease caused by a genetic mutation. One such disease is Saethre-Chotzen syndrome.

This page is

• People who think their baby’s head is oddly shaped
• People who want to know about congenital genetic disorders

I am writing to.

There is very little information about Saethre-Chotzen syndrome in Japan, but there is a wealth of information overseas. Some people are not good at reading English.
This page refers to information from research papers and overseas public institutions, so you can understand Saethre-Chotzen syndrome without reading English pages. This
is the perfect page for people who want to obtain detailed information not only from Japan but also from overseas.

By the time you finish reading this page, you will have learned everything from basic knowledge about Saethre-Chotzen syndrome to specific treatment measures, so you will be able to think about how to deal with the disease from an early stage.
Even if your baby has Saethre-Chotzen syndrome, you as a parent can provide your baby with a comfortable life.

However, not knowing anything about the disease can delay your decision as a parent. If you delay your decision, you may not be able to treat the condition.
To prevent this, learn about Saethre-Chotzen syndrome.

Saethre-Chotzen syndrome causes craniosynostosis

One of the causes of craniosynostosis is Saethre-Chotzen syndrome.

Craniosynostosis is a condition in which the shape of a baby’s skull is determined before the baby’s brain has fully developed.

The skull is not one bone, but is divided into seven parts. When a baby is born, the seven parts are not attached. As
time passes, the parts of the skull will attach to match the size of the brain, depending on how much the baby’s brain has grown.

However, craniosynostosis is a condition in which parts of the brain join together before the baby’s brain has fully developed.

What happens if all seven parts are attached prematurely? The brain wants to grow but can’t, so pressure builds up and it gets squeezed.

If only the right side of the head is attached, the left side will be empty, and the brain will grow toward the empty left side.
This will result in a head shape with the left side protruding.

There are multiple patterns of craniosynostosis, such as when all seven parts are attached at once, when only two parts are attached, or when only three parts are attached. What they all have in common is that the head is misshapen.
When the head is misshapen, various physical disorders occur in the baby.

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Deciding on clothing size without considering growth periods

To help understand craniosynostosis, let’s compare the skull to a junior high school uniform and the brain to a developing body.

When you first entered junior high school, your parents probably bought you a uniform. They probably ordered it with your growth period in mind.
So, even if your uniform was too loose for your first year of junior high school, have you ever had the experience of it fitting just right when you were in the third year?

So let’s say you buy a uniform that fits your body when you’re in the first year of junior high school. What will happen if you don’t change the size of the uniform when you reach the third year of junior high school?

The limbs stretch out, and what should be long sleeves end up looking like 3/4 length or short sleeves. Arms and legs sticking out of the uniform just look weird.
But if the brain sticks out, it can affect the head and face, leading to physical problems.

If the uniform is too tight, it may reduce blood flow to the body. If the uniform is too tight, the blood flow and cerebrospinal fluid circulation in the brain will also be reduced.

Impact on your baby’s life

The problem does not end when you develop craniosynostosis and your head becomes misshapen.

When a baby has an irregular head shape, the most common symptoms are:

• headache
• Temporomandibular joint disorder
• Developmental delay
• astigmatism
• 斜頸
• 脊柱側彎症

Complications of craniosynostosis

The effects of craniosynostosis are felt in the brain and adjacent face. These effects are called complications. Symptoms can also cause complications.

Respiratory failure due to upper airway narrowing

To put it simply, the upper airway is from the nostrils to the throat. Due to wrinkles, some part of the upper airway becomes narrow, making it difficult to breathe.

Chiari Malformation

Chiari malformation is a condition in which the head shape changes, causing the cerebellum and brain stem to protrude from their original positions, resulting in physical disorders. Typical disorders in babies include difficulty breathing and swallowing.

水頭症

Hydrocephalus is a condition in which the brain enlarges due to an excess of cerebrospinal fluid.

The deformation of the head makes it difficult for cerebrospinal fluid to circulate. Cerebrospinal fluid is produced in the ventricles, and if circulation is poor, it cannot escape from the ventricles. If cerebrospinal fluid
continues to accumulate in the ventricles, the ventricles expand, and the entire brain also expands. The expansion of the entire brain causes the brain to be pressed hard against the skull, causing brain damage.

Brain damage can cause headaches, vomiting, and involuntary muscle contractions and relaxations.

squint

Strabismus is a condition in which the eyes look in different directions. For example, the right eye looks straight and the left eye looks up. One of the causes of strabismus is poor nerve transmission. Craniosynostosis is what interferes with nerve transmission.

Malocclusion due to tooth alignment

When the head shape is not normal, it affects the adjacent face and causes malocclusion, which is when the upper and lower jaws do not fit together properly. This
can lead to protruding teeth or a crooked jaw.

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Saethre-Chotzen syndrome is caused by an abnormality in the TWIST gene

Saethre-Chotzen syndrome is caused by a mutation in the TWIST gene. The TWIST gene mutation is caused by a deletion of 7p21.1
. To put it simply, 7p21.1 is where the TWIST gene is located.

Saethre-Chotzen syndrome is not the only cause of craniosynostosis.

for example,

• Crouzon syndrome
• Apert Syndrome
• Pfeiffer syndrome
• Antley-Bixler syndrome
• Carpenter syndrome

The difference between these syndromes and Saethre-Chotzen syndrome is the causative gene. Säethre–Chotzen syndrome is caused by the TWIST gene.

Below, we will explain 7p21.1, where the TWIST gene is located.

Deletion of 7p21.1 causing abnormality in the TWIST gene

A deletion is a phenomenon in which a part of a chromosome or DNA is lost. In Saethre-Chotzen syndrome, part of 7p21.1 is deleted.

7p21.1 represents the location of the autosome. It is like an address.

• 7 is the seventh autosome
• p is the short arm of the chromosome
• 21.1 shows the position in p.

Would it be easier to understand if you think of the TWIST gene living at the address 7p21.1? Let’s say a fire breaks out at the address 7p21.1.
If that happens, the TWIST gene will also be affected.

This fire is a loss.

The TWIST gene prevents the skull from joining together too quickly

Craniosynostosis occurs when the TWIST gene does not function properly, because the role of the TWIST gene is to adjust the skull so that it does not fuse together too quickly.

What is the TWIST gene?

The TWIST gene is a blueprint for making a protein called TWIST. For example, if a fire breaks out at an address where the blueprint is located, the blueprint will be lost or partially lost. The protein cannot be made properly. This state is a genetic mutation.

When there is a mutation in the TWIST gene, the protein cannot be produced, causing a condition called craniosynostosis in the baby’s body.

The role of TWIST is to not let bones break down

TWIST is a protein that acts on mesenchymal stem cells. Mesenchymal stem cells are the cells that become bone. TWIST inhibits mesenchymal stem cells from becoming bone.

Without TWIST, the bones would quickly turn to bone. When the bones quickly turn to bone, the bones quickly fuse together, resulting in craniosynostosis.

Insufficient amount of TWIST causes Saethre-Chotzen syndrome

Even if one TWIST gene is normal, there is an insufficient amount of TWIST. If there is insufficient amount, Saethre-Chotzen syndrome occurs.
TWIST cannot exert its power unless it is a dimer.

A dimer is like two people as one, and it works because there are two of them, not one alone. To put it in perspective, it’s like a bicycle tire.
A bicycle needs one tire on the front and one on the back, and if either one is missing, the bicycle won’t run properly.

A baby inherits one chromosome from each mother and father, and that chromosome carries the TWIST gene.

For example, if the TWIST gene inherited from the father has a mutation, but the TWIST gene inherited from the mother is normal, the amount of TWIST will be half, since it is only produced from the gene inherited from the mother.

TWIST is a dimer, which is why it can slow down the process of bone formation.
In Saethre-Chotzen syndrome, where only one TWIST is present, the process of bone formation cannot be slowed down, leading to craniosynostosis.

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Few prenatal tests, many postnatal tests

Prenatal diagnosis of Saethre-Chotzen syndrome is limited to certain conditions. If the conditions are not met, there are almost no cases of prenatal diagnosis. Most cases of Saethre-Chotzen syndrome can be detected by testing after birth.

The condition for prenatal testing is when a gene mutation has been found in a family, meaning that either the mother or the father or both have the mutated gene, or when a person diagnosed with Saethre-Chotzen syndrome becomes a parent.

For example, if one parent has a gene mutation, there is a 50% chance that it will be passed on to the baby.

Prenatal testing is a definitive test

Prenatal diagnosis consists of amniocentesis and chorionic villus sampling. Amniocentesis is a test performed during the 15th to 16th week of pregnancy. A needle is inserted into the mother’s abdomen to collect amniotic fluid.

This is because amniotic fluid contains the baby’s cells, which include chromosomes, allowing us to test for chromosomal and DNA abnormalities.

Chorionic villus sampling is performed between the 11th and 14th weeks of pregnancy, by inserting a needle into the mother’s abdomen to extract chorionic villus cells from the placenta.
As with amniocentesis, chorionic villus sampling contains the baby’s cells, making it possible to test for chromosomal and DNA abnormalities.
Compared to amniocentesis, chorionic villus sampling can be performed at an earlier stage of pregnancy and can extract a large number of the baby’s cells.
However, chorionic villus sampling is less reliable than amniocentesis, as chorionic villus sampling does not contain only the baby’s cells.
If chorionic villus sampling is unsuccessful, amniocentesis is performed.

Amniocentesis and chorionic villus sampling involve inserting needles into the mother’s body, so they carry the following common risks:

• Water breaks
• Bleeding
• Intrauterine infection
• Premature birth
• Amniotic fluid embolism
• Maternal damage due to needle aspiration
• Miscarriage, stillbirth

Although the probability is low, it is important to understand that it is a test that carries risks.

With early treatment and examination, your baby can live a comfortable life.

If you notice something unusual about your baby’s head shape, go to a pediatrician, surgeon, or plastic surgeon as soon as possible.
If abnormalities are found after examining the morphology and bodily functions, a DNA test will be performed and treatment will begin.

Although the genetic mutation that causes Saethre-Chotzen syndrome cannot be cured, there are treatments for craniosynostosis: cranioplasty
and cranial distraction devices.

If not treated early after birth, the head shape will become completely fixed, making treatment difficult.

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Please don’t think my baby is different.

Saethre-Chotzen syndrome can affect people of any race, ethnicity, or gender, with an incidence rate of 1 in 25,000 to 50,000.

For example, the population of Japan is about 126.5 million. If it’s 1 in 25,000, that’s 5,000 to 5,500 people.
That’s roughly the same as the number of coronavirus infections in Tokyo in mid-June 2020. It’s rare, but it’s not a probability that it will never happen.

The cause of craniosynostosis is Saethre-Chotzen syndrome. The cause of Saethre-Chotzen syndrome is a mutation in the TWIST gene due to a deletion of 7p21.1.

How early you suspect Saethre-Chotzen syndrome and get a diagnosis and treatment can change your baby’s life.
If you feel that your baby’s head shape is abnormal, why not take a full autosomal partial deletion test?
Saethre-Chotzen syndrome is not the only cause of craniosynostosis.

If the test shows no abnormality, other causes should be considered and treated promptly, because the shape of the head is determined.

Hiro Clinic NIPT performs tests for all autosomal partial deletions
, boasting a negative predictive rate of 99.9%. In other words, tests with a high negative predictive rate greatly support parents in making accurate decisions to ensure that their baby lives a comfortable life. We
want our babies to be happy, so we want them to be. What parents can do for their babies is to learn about this disease and take action as soon as possible.
I hope that this page will encourage you to keep Saethre-Chotzen syndrome in the back of your mind.