Down syndrome

What is Down syndrome?

Down syndrome or trisomy 21 is a genetic disorder caused by the presence of an extra third chromosome in the 21st homologous pair. Chromosomes contain genes that carry all the information for the proper development and maintenance of the human body.

Human cells normally contain 46 chromosomes, which can be arranged in 23 homologous pairs. One half of the 23 chromosomes originates from the mother’s egg and the other from the father’s sperm.

In most cases of Down Syndrome, two twenty-first chromosomes are inherited from the mother instead of one and one from the father, resulting in three copies of the twenty-first chromosome instead of two, hence the disease is also known as trisomy 21.

In Down syndrome, the presence of a third chromosome in the 21st homologous pair leads to increased expression of the genes that are located on this chromosome.

Inheritance of the entire extra 21st chromosome accounts for 95% of all cases of trisomy 21. To date, the cause of this genomic mutation is unknown.

The only known risk factor is the mother’s age at conception. The older the mother is at conception, the greater the risk of conceiving a baby with trisomy 21.

All sufferers of this disease have mild to moderate cognitive impairment, distinctive facial features, and low muscle tone from early childhood. The disease is also often associated with heart defects, leukemia and the early development of Alzheimer’s disease.

What are the characteristic features of the genomic mutation?

Despite the variability, people with Down syndrome look in a specific way and this is expressed in:

  • Flattened nose and smaller mouth: The characteristic facial shape in individuals with Down syndrome includes a flatter nose and smaller mouth. This gives their face a distinctive appearance.
  • Protruding tongue and small ears: People with Down syndrome often have a larger and protruding tongue. The ears may also appear smaller and lower positioned.
  • Eyes turned upward: In many cases, individuals with Down syndrome have a characteristic physical feature in which the eyes they are turned slightly upwards.
  • Rounded skin fold at the inner corner of the eyes: This physical characteristic, called epicanthus, is manifested by a rounded skin fold at the inner corner of the eyes in some individuals with Down syndrome.
  • Hands are short and wide, fingers are short: Individuals with Down syndrome often have short and wide hands as well as short fingers. This is due to different anatomical features of the bones and structure of their hands.
  • White spots on the colored part of the eye: People with Down syndrome may have white spots on the iris area. of the eye, known as lentigo.
  • Decreased muscle tone at birth: Newborns with Down syndrome often have reduced muscle tone, which can make them softer and more flexible.
  • Slowed growth and development: Individuals with Down syndrome often reach their mother’s height, but grow more slowly and their development may be delayed. This aspect relates to both physical and mental development.

This syndrome affects not only the physical appearance of individuals, but also their mental status and development.

Treatment and support for individuals with Down syndrome depend on individual needs and include early intervention treatment, educational programs and social support to enable them to achieve the highest degree of independence and quality of life.


Down syndrome and cognitive impairment

Genome mutation is a leading cause of cognitive impairment.

Cognitive development is delayed and perceptual difficulties persist throughout life. Scientists are trying to determine what is the cause of this dysfunction.

The average brain volume in a person with trisomy 21 is smaller and some brain structures such as the hippocampus and cerebellum do not function properly. The hippocampus is important for learning and memory.

Through research on humans and laboratory mice, scientists are trying to understand which genes on the third chromosome in the 21st homologous pair affect cognitive abilities.

Treatment for Down syndrome

There is currently no cure for trisomy 21. Although the genetic cause of this genomic abnormality is known to scientists, research is only now being done to discover which genes in the extra chromosome are the cause of the various manifestations of trisomy 21.

Some progress has been made using lab mice toward finding potential drugs that could improve cognition, but it is too early to test in humans.

Some people with heart and gastrointestinal abnormalities will need corrective surgeries soon after birth.

Regular examinations should be carried out to detect possible vision problems, hearing loss, ear infections, hypothyroidism and other clinical conditions as early as possible.

Despite this complex of physical and mental challenges, people with Down syndrome are distinguished by their uniqueness and ability to bring joy and enrichment to society.

It is important to emphasize that the support and education resources available today allow these individuals to develop their skills and potential, achieving greater independence and inclusion in society.

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