Biology

Down Syndrome

Down syndrome is a genetic disorder. Mutation is the most common cause of genetic disorders. Mutation can be of two types, firstly spontaneous and secondly, induced. In this syndrome, an extra chromosome gets added to the normal 46. Chromosomes are the genetic material present inside the nucleus of both animal and plant cells. DNA and proteins make the chromosomes. We will study it in detail here.

down syndrome

Down Syndrome Meaning

Down syndrome is the trisomy of chromosome 21 i.e. chromosome number 21 is extra. This disease was first discovered by British physician John Langdon Down in 1866; therefore it got its name after him. It is also sometimes referred to as mongolism.

The IQ of a patient with this syndrome turns out very low. A young adult possesses an IQ of an 8 to 9-year-old child.

Down syndrome is incurable. It causes both mental and physical retardness. The life expectancy for people with this syndrome is quite shorter than normal people. With proper help and good healthcare, a person with this syndrome can live up to 50-60 years.

Cause of Down Syndrome

In normal conditions, both parents pass half chromosomes to their offspring. However, in the case of this syndrome, one of the pairs doesn’t separate. And no wonder extra chromosomes get available for the offspring.

There are now three copies of chromosome 21. This inability of separation is often referring as “non-disjunction”. The normal pairs should be 23 (46 chromosomes). This disorder is most common in the US. About every 1 out of 700 children are born with this disease.

Symptoms of Down Syndrome

Each person having this syndrome varies from mild to severe health issues. Some have very serious problems meanwhile others can have very mild or moderate dysfunctions.

Some common symptoms of include-

  • Protruding tongue
  • Size of head smaller than the normal
  • Protruding (bulging) tongue
  • Upward slanting eyelids
  • Bad muscle tone

Moreover, a child with this syndrome might have weak learning ability, reckless behaviour, and bad attention.

Meanwhile, they can have various medical issues such as

  • Hypothyroidism
  • Obesity
  • Heart diseases
  • Memory issues
  • Bad eye vision and hearing disorders
  • Alzheimer’s disease.

Types of Down syndrome

There are three types-

Trisomy 21

Certainly, it is the most common type of Down syndrome. It is due to the non-disjunction of cells during the development stage. Therefore, in it, the person has three chromosomes 21 instead of two. This leads to both physical and mental incapabilities.

Late pregnancies have higher risks of trisomy 21. Pregnancies in the late 30s and 40s are at higher risk of this disease. In most cases, the extra chromosome comes from the maternal side i.e. the egg.

Mosaic Down syndrome

It is often termed mosaicism. In this type of Down syndrome, only some cells possess trisomy. In other words, in mosaicism, only some cells of the body have an extra chromosome 21. This is a rare form of Down syndrome and no wonder it can’t be easily diagnosed. The diagnosis for it usually occurs between the age of 1-4 years.

The mosaic Down syndrome occurs after the fertilization of male and female gametes. However, persons with this type have higher intellectual ability than trisomy 21.

Translocation Down syndrome

In this type of Down syndrome, the extra third chromosome gets attached to one of the other chromosomes and creates the problem. For instance, the extra chromosome might get attached to the 13th, 14th, or 18th pair of chromosomes. However, there is very little difference between trisomy 21 and Translocation Down syndrome.

If this translocation is found to be inherited from parents, then certainly the parents might be having difficulty in getting pregnant, have miscarriages, and most importantly have a very high risk of having a child with health issues.

Who are at risk of having Down syndrome?

However, this syndrome can occur at any age but the mothers above the age of 35 to 40 years. In the 30s the chances of having a baby with this syndrome are one in 350 on the other hand after the 40s it becomes one in 100.

Diagnosis of Down syndrome

It can be diagnosed by Amniocentesis or ultrasounds. Amniocentesis is the process in which amniotic fluid is drawn from the uterus and is sent for testing for any type of disease or deficiencies. Moreover, the tests are done after the 15 to 22 weeks of pregnancy.

Two trimesters of ultrasounds in case of mothers with more age are-

  • First trimester- An ultrasound and blood test is for checking of Down syndrome. If the doctors suspect, he might get you an amniocentesis after the 15th week of pregnancy.
  • Second trimester- A quadruple marker screen and ultrasound helps in the diagnosis. It diagnoses this syndrome and any deformity of the brain or spinal cord. If the test is susceptible, then the child has a higher chance of birth defects.

Noninvasive prenatal testing (NIPT) is present for the early diagnosis of the syndrome.

Abortion and Down Syndrome

There is a huge conflict between parents about aborting a child with this condition. The plea for abortion of the child with this syndrome was refused by the Supreme Court.

However, the Supreme Court says that abortion above 20 weeks is only allowed in case if the mother or the fetus has a life threat. Further, the abortion of a fetus with Down syndrome still remains the subject of debate. There are many social laws that consider abortion unethical.

Treatments of Down syndrome

Actually, there is no ultimate cure for this. But with proper medications and little help; the life expectancy can be higher. Moreover, life can be lesser complex with these. There are many therapies present for people suffering. If these therapies are available at an early age the child can get great help.

Some of those therapies include-

  • Speech therapy
  • Physical therapies
  • Special education centres
  • Self-care techniques and
  • Programs offering jobs.

FAQs on Down Syndrome

Question 1- What is the cause of Down syndrome?

Answer 1- It is due to the addition of an extra chromosome 21. As a result, the normal functioning of the body gets disturbed. Many physical and mental deformities happen. Furthermore, the abnormality can be due to various issues such as mutation or other environmental factors.

Question 2- Is Down syndrome curable?

Answer 2- No; there is no ultimate cure for it. However, with proper health management and guidance, life expectancy can increase.

Question 3- What are the main symptoms of Down syndrome?

Answer 3- The main symptoms of include:

  • Small head
  • Flattened face
  • Protruding tongue
  • Small or unusual ears
  • Speech problem and short stature
  • Difficulty in learning.

Question 4- What are the three main types of Down syndrome?

Answer 4– Three main types are-

  • Trisomy 21- It is the most common type. In this, the cells possess an extra 21 i.e. 3 chromosomes instead of 2.
  • Translocation Down syndrome– In this, an extra chromosome attaches to any other chromosome like with 12th, 13th, or 17th.
  • Mosaic Down syndrome– In this type, only a few cells show trisomy others are normal.
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