Down syndrome

 Down syndrome is a genetic condition in which a person is born with an extra chromosome: instead of 46 chromosomes, there are 47 in the nucleus of each cell.

Each chromosome contains hundreds, thousands of genes. Genes hold the information that determines a person’s traits, that is, all the characteristics they inherit from their parents.

In Down syndrome, the extra chromosome causes delays in the child’s mental and physical development.

The physical characteristics and medical complications associated with Down syndrome can vary widely from child to child.

Although it cannot be prevented in any way, Down syndrome can be detected during pregnancy.

Some of the ailments associated with this syndrome can be treated, and there are also a wealth of resources available to help children and their families live with this disease.

Many children with Down syndrome go to school and participate in the same activities as their peers.

Some of them go to university, and many conquer an independent lifestyle. Some, on the other hand, continue to live at home, but have their jobs and find their success in life.

Down syndrome is characterized by the presence of an extra chromosome in the cells: instead of 46 chromosomes in the nucleus of each cell there are 47, that is, there is a chromosome n. 21 more; hence also the term Trisomy 21.

The causes of Down syndrome

Normally, at the time of its conception, the child inherits genetic information from both parents in the form of 46 chromosomes: 23 from the mother and 23 from the father.

However, in most cases of Down syndrome, the child inherits an extra chromosome 21, for a total of 47 chromosomes instead of 46. It is this excess genetic material that causes the symptoms associated with the syndrome.

Although the exact causes of Down syndrome are not yet known, and there is no way to prevent the chromosomal error that causes this condition, scientists have noted that women over the age of 35 are significantly more likely to greater than having a child with this syndrome.

How is Down syndrome characterized?

Children with Down syndrome tend to exhibit broadly the same physical characteristics, such as a flat face profile, same upturned eyes, small ears, and protruding tongue.

However, while some children with Down syndrome do not have significant health problems, others may develop disorders that require specialized treatment: for example, nearly half of children with Down syndrome have congenital heart defects .

In addition, children with this syndrome have an increased risk of developing pulmonary hypertension, a very serious disease that leads to damage to the lungs.

About half of children with Down syndrome have hearing and vision problems.

The decrease in hearing ability may depend on the accumulation of fluid in the inner ear due to malformations of the ear itself.

Vision problems consist of strabismus, myopia or presbyopia, and an increased risk of cataracts.

Other health conditions that appear more frequently in children with Down’s syndrome are problems with the thyroid, stomach, intestines, seizures and breathing problems, such as sleep apnea and asthma, obesity.

And also an increased likelihood of contracting infections and an increased risk of childhood leukemia.

People with Down syndrome sometimes have an unstable upper spine. This feature can be evaluated by the doctor before starting sports or physical activities.

Fortunately, many of these problems are treatable.

Screening tests and diagnostic tests

There are two types of prenatal tests to detect Down syndrome: screening tests and diagnostic tests.

i test di screening

  • Screening tests do not identify the disease, but rather estimate the risk that the fetus is affected.
  • They are cheap and easy to make.
  • They cannot give definitive answers about the diagnosis.
  • They are used to help parents decide whether to get diagnostic tests.

the diagnostic tests

  • They provide a confident diagnosis.
  • They are 99% accurate in detecting Down syndrome and other chromosomal abnormalities.
  • They are performed inside the uterus, so they are associated with a certain risk of miscarriage and other complications.
  • For this reason, invasive diagnostic tests were previously recommended only for women over 35, those with a family history of genetic defects, or those who had received strange results from screening tests.

As far as screening tests are concerned, these include the following tests:

  • Nuchal translucency test.
    • This test is performed between the 11th and 14th week of pregnancy using an ultrasound to measure the space between the folds of tissue in the developing baby’s neck.
    • Children with Down syndrome or other defects tend to accumulate fluid in that area of ​​their body, making the space appear larger than normal.
    • This measurement, together with the mother’s age, and the fetus’s gestational age, can be used to calculate the odds that the baby has Down syndrome.
  • Tri test.
    • This test measures the amount of three marker substances in the mother’s blood . It is normally done between the 15th and 18th week of pregnancy.
  • Integrated testing.
    • In this test, the results of the first trimester screening (with or without nuchal translucency) and those of blood tests with the (so-called) tri-test are used to arrive at a more accurate analysis of the results.
  • Morphological ultrasound.
    • A morphological ultrasound – which is usually performed between the 18th and 20th week together with blood tests – allows you to check some of the physical characteristics of the fetus that may be associated with Down syndrome.
  • Test del DNA.
    • This test analyzes the fetal DNA present in the mother’s blood.
    • It is performed during the first trimester, and is more accurate in detecting trisomy 21 (Down syndrome is also called trisomy 21), than a standard blood test.
    • At present, this type of test is only prescribed for women who are at particular risk of having a baby with Down syndrome.

As far as diagnostic tests are concerned, these include the following tests:

  • Villocentesi (Chorionic villus sampling, CVS).
    • CVS involves taking a small sample of the placenta from the cervix or through a needle inserted into the abdomen.
    • The advantage of this test is that it can be performed during the first trimester of pregnancy, typically between the tenth and twelfth week.
    • Its disadvantage is that it carries a -slight- risk of miscarriage more than amniocentesis, and other complications.
  • Amniocentesis.
    • This test, performed between the fifteenth week of pregnancy and the twentieth week of pregnancy , involves the removal of a small amount of amniotic fluid through a needle inserted into the abdomen.
    • The cells taken can then be analyzed to detect the presence of chromosomal abnormalities.
    • Amniocentesis carries a small risk of complications, such as early labor and miscarriage.
  • Percutaneous umbilical cord blood sampling  (PUBS) or cordocentesis.
    • Usually this test is done after 18 weeks. The test usually involves using a needle to take a small sample of blood from the umbilical cord.
    • This test has similar risks to that associated with amniocentesis.

After the birth of the child, in the event that the doctor suspects Down syndrome based on the physical characteristics detected, it is possible to carry out an examination of the carotype (i.e. the set of characteristics of shape, size, number and properties of the chromosomes) A test in which the chromosomes of a blood or tissue sample are made visible. In this way it is possible to verify the correctness of the diagnosis or not.

How to behave if the syndrome is diagnosed

If you are the parent of a child diagnosed with Down syndrome, to better overcome the initial shock and disappointment, and to find ways to look to the future with more serenity, it may be helpful to talk to the parents of other Down children .

Experts recommend that children with Down syndrome undergo physical and occupational therapies as soon as possible, as well as relying on speech therapists and educators so that these professionals can work with the child from the beginning to encourage and accelerate his development .

It can be very difficult deciding which school to send your child to. In fact, some children with Down syndrome need to be managed better, within specialized programs.

Other children respond better when in contact with individuals without Down syndrome. Recent studies have shown that situations of inclusion bring benefits both to the child with Down syndrome and to other children.

Katherine Johnson, M.D., is a board-certified obstetrician-gynecologist with clinical expertise in general obstetrics and gynecology, family planning, women’s health, and gynecology.

She is affiliated with the Obstetrics and Gynecology division at an undisclosed healthcare institution and the online platform, Maternicity.com.

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