- Preparing to welcome your new baby
- Monosomy is a condition in which one chromosome is missing
- Types of monosomy diseases
- Partial chromosome deletion
- Difference in lifespan between trisomy and partial deletion
- Only Hiro Clinic NIPT can test for trisomy and monosomy at the same time
Preparing for the new baby
“Is there anything I can do for the baby even before it’s born?” “
I’m doing moderate exercise and being careful about what I eat, but…”
“I’m the only one making my wife go through all the hardships, and I wonder if there’s anything I can do…”
As a solution to your worries, let me suggest genetic testing for your baby.
When it comes to genetic testing, testing for trisomy is well known,
but chromosomal abnormalities include not only trisomy but also monosomy.
The reason we recommend testing is so that you can start preparing for the arrival of your baby.
For example, if a test reveals that your baby has a chromosomal abnormality,
- Organize your living environment
- Find a support organization
- Find a suitable medical institution for treatment
As a parent, there are many preparations you need to make.
Imagine if you didn’t know your child had a chromosomal abnormality beforehand.
The child would probably continue to suffer from symptoms until you noticed. Furthermore, if you
were to suddenly find out that your child had an illness, you would probably panic.
It is well known from recent disasters that people tend to turn a blind eye or make poor decisions in an emergency situation when they panic.
However , if you know your baby’s genetic information before he or she is born, you can start preparing today. Your support is especially important when it comes to the symptoms of monosomy
. Your actions will determine how comfortable your child will be.
By reading this article, you will understand:
- What is Monosomy?
- About partial deletions
- Lifespan of partial chromosome deletions and trisomies
- Clinics and tests that can provide trisomy and monosomy test results
If you want to make your newborn baby happy
, this article provides information for you.
Monosomy is a condition in which there are not enough chromosomes
Chromosomes are the place where the human blueprint is
Chromosomes are found in cells *1 and are where the blueprint for the human body is recorded.
The human body is created based on this blueprint.
If there is an abnormality in the chromosomes, it will affect the blueprint.
The effect of the blueprint on the human body can cause a variety of malfunctions.
For example, if the blueprint were rewritten or parts were missing, the things the human body needs would not be produced.
This means that you may be lacking something that is essential to life.
*1 Cell: The smallest part that makes up the human body.
Humans have 46 chromosomes (2 per group)
Humans have two types of chromosomes, totaling 46.
- Two sex chromosomes
- 44 autosomes
Here is the breakdown.
Sex chromosomes are related to a person’s gender, and whether they are male or female is determined by what sex chromosomes they have.
Autosomes are chromosomes other than the sex chromosomes.
Furthermore, chromosomes are divided into groups of two:
one group for sex chromosomes and 22 groups for autosomes.
Autosomes are grouped into numbers 1 to 22, and the lower the number, the larger the chromosome.
Monosomy is the absence of one of two chromosomes
The absence of one chromosome in one group is not normal for the human body.
For example, a bicycle can be ridden because it has two tires.
However, if one tire is stolen or the bicycle comes off the road, you will not be able to ride the bicycle properly.
Two chromosomes function normally to create the human body.
However, if only one chromosome is functioning, the blueprint for the human body is insufficient.
This insufficient blueprint can cause various malfunctions in the human body.
Types of Monosomy
Monosomy can occur in both sex chromosomes and autosomes.
The type of disease varies depending on which chromosome monosomy occurs in.
Turner syndrome, a common sex chromosome monosomy
Turner syndrome accounts for the majority of all monosomy disorders.
Turner syndrome symptoms are mild,
but without parental support, children may not feel comfortable.
Turner syndrome occurs only in girls or women.
It is an incurable disease that can cause spontaneous abortions and is a condition in which one of the two sex chromosomes is completely missing.
If you provide your child with adequate support, their life expectancy will be comparable to that of a healthy person.
Autosomal monosomy is rare
Monosomy can also occur in autosomes.
However, since many miscarriages occur early in pregnancy, it is difficult to detect.
Chromosome deletion
Monosomy can easily be confused with partial deletions .
Monosomy is an abnormality in the number of chromosomes, where one of the paired chromosomes is missing.
On the other hand, when part of one of the paired chromosomes is missing, it is called a partial deletion .
For example, let’s replace two chromosomes with two books (A and B).
Book A has 100 pages, but book B is missing 5 of the 100 pages.
In other words, there are two books, but one of them has some defects.
These chromosomal abnormalities are called structural abnormalities, as opposed to monosomies and trisomies, which are numerical abnormalities.
Structural abnormalities of chromosome 22
Structural abnormalities of chromosome 22 occur in the 22nd group of autosomes, in which one of the two chromosomes is partially non-functional.
22q13 and 22q11.2 are
- Autosome group 22
- q is the chromosome with the long arm (chromosomes have long and short arms)
They’re the same up to that point, but the difference is in the non-functional area beyond that.
22q13 deletion syndrome
Symptoms of 22q13 deletion syndrome include:
- Decreased muscle tone in the neonatal period *1
- Global developmental delay
- Excessive growth
- Absence or delay in speech
However, it is believed that there are no life-threatening organ abnormalities.
*1 Decreased muscle tone: A condition in which muscles are difficult to move. In babies, this can mean that they have difficulty holding their head up, and they may have a weak cough, making them more susceptible to pneumonia.
22q11.2 deletion syndrome
Symptoms of 22q11.2 deletion syndrome include:
- Mental development disorder
- Congenital heart disease
- Immune dysfunction
- Distinctive facial features
- Learning disabilities
- ADHD
If you have a 22q11.2 abnormality, your life expectancy will vary depending on how severe your congenital heart disease is,
which often includes tetramicro of Fallot and interrupted aortic arch.
Differences in life expectancy between trisomy and partial deletion
Trisomy is a condition in which there are too many chromosomes
In the sex chromosome group and the autosome group 1-22, two chromosomes per group are normal, right?
However, trisomy is a condition in which there are three chromosomes per group, so there are more blueprints for the human body.
As a result, the excess chromosomes have various adverse effects on the human body.
In other words, whether the number of chromosomes in a group is one, three or more, it will cause physical abnormalities.
Comparing lifespan of partial deletions and trisomies
When comparing partial deletions and trisomies, trisomy tends to result in a shorter life span.
This is because diseases caused by trisomy are more severe than those caused by partial deletion.
The life expectancy of partial deletion depends on the progression of congenital heart disease, but many of the other symptoms are not life-threatening.
In addition, the number of cases is currently small.
Therefore, looking at partial deletions and trisomies as a whole, trisomies tend to have a shorter life expectancy.
Trisomy can also occur in both sex chromosomes and autosomes.
Trisomy occurring in autosomes is said to result in a shorter lifespan than in sex chromosomes.
Life expectancy of individuals with sex chromosome trisomy is the same as that of healthy individuals
Symptoms of sex chromosome trisomy are often mild, and as long as you are careful to avoid complications, your life expectancy will be no different from that of a healthy person.
Sex chromosome trisomies include
There is.
Life expectancy of individuals with autosomal trisomy tends to be shorter than that of healthy individuals
In this section, we will explain the three trisomies that account for 70% of autosomal trisomies.
in particular,
Trisomy 21 (Down Syndrome)
The general life expectancy is 50 to 60 years.
It accounts for approximately half of the diseases caused by trisomy.
A condition in which there are three chromosomes in the 21st group of autosomes.
Previously, life expectancy was less than 50-60 years, but with advances in medical technology, life expectancy is increasing.
Trisomy 13 (Patau syndrome)
Generally, 50% of them have a lifespan of less than one month, and 90% have a lifespan of less than one year.
Most babies born with trisomy 13 end up stillborn, with only about 4% able to give birth.
Of these 4%, less than 10% survive for more than a year.
There are three chromosomes in the 13th group of autosomes.
There have been confirmed cases of heart disease and even death.
Trisomy 18 (Edwards syndrome)
Generally, 90% of them have a lifespan of less than one year.
A condition in which there are three chromosomes in the 18th group of autosomes.
Most babies with trisomy 18 are stillborn.
In cases where stillbirth does not occur, in addition to heart disease,
- Pulmonary and respiratory complications
- 消化器合併症
- Urinary complications
- Malignant tumors
There is a risk of many complications.
Hiro Clinic NIPT is the only place where you can test for trisomy and monosomy at the same time.
Why not try Hiro Clinic NIPT for your future baby ?
The reason we use Hiro Clinic NIPT is that it can obtain monosomy test results along with trisomy results with less risk to the mother.
In order to obtain monosomy results at another hospital, tests that pose risks to the fetus and mother, such as amniocentesis and chorionic villus sampling, must be performed.
For example, Turner syndrome caused by monosomy will determine how comfortable your child will be depending on your support. Hiro Clinic NIPT is a system that helps you make choices and prepare before the baby is born.
It’s the perfect test for you who want to prepare in advance for the happiness of your baby.
【References】
- Japan Society of Obstetrics and Gynecology – Chromosomal Abnormalities
- Orphanet French National Institute of Health and Medical Research – Monosomy 22q13
- Orphanet French National Institute of Health and Medical Research – Monosomy 21
- MSD Manual – Trisomy 18
- Rare Disease Information Center – 22q11.2 Deletion Syndrome
Article Editorial Supervisor
Dr Hiroshi Oka
NIPT specialist clinic, MD
Graduated from Keio University, School of Medicine
