What is the Difference Between Mosaic Down Syndrome and Trisomy 21

Mosaic Down syndrome and Trisomy 21 are two related medical conditions characterized by the presence of an extra chromosome in cells. The key difference between Mosaic Down Syndrome and Trisomy 21 lies in how this additional chromosome manifests.

Mosaic Down syndrome arises when an individual possesses both typical cells and cells with an extra chromosome, whereas Trisomy 21 entails the presence of an extra chromosome in all of a person’s cells.

CONTENTS

1. Overview and Key Difference
2. What is Mosaic Down Syndrome  
3. What is Trisomy 21
4. Similarities – Mosaic Down Syndrome and Trisomy 21
5. Mosaic Down Syndrome vs Trisomy 21 in Tabular Form
6. Summary – Mosaic Down Syndrome vs Trisomy 21
7. FAQ – Mosaic Down Syndrome and Trisomy 21

What is Mosaic Down Syndrome?

Mosaic Down syndrome is a rare form of Down syndrome. People with this condition may have fewer symptoms of Down syndrome. This is because people with mosaic Down syndrome have a mixture of cells. Some have two copies of chromosome 21, and some have three copies. The symptoms of mosaic Down syndrome include almond-shaped eyes that tend to slant upward, a neck that is shorter than average, a flattened face, small ears, white spots on the iris of the eye, poor muscle tone, loose joints, shorter height or slower growth, small hands and feet, small pinky fingers, and a tongue that sticks out of the mouth. Individuals with Mosaic Down syndrome can live up to 80 years.

Mosaic Down syndrome can be diagnosed through testing a sample of cells from the placenta or amniotic fluid, as well as through physical examination. Furthermore, Mosaic Down syndrome can be managed through physical therapy, language and speech therapy, as well as occupational therapy.

What is Trisomy 21?

Trisomy 21, also known as Down syndrome, is a genetic disorder that is caused by an extra full or partial copy of chromosome 21 in all cells of the body. The symptoms of this condition may include a flattened face, small head, short neck, protruding tongue, upward slanting eyelids, unusually shaped or small ears, poor muscle tone, broad, short hands with a single crease in the palm, excessive flexibility, tiny white spots on the iris of the eye and short height and intellectual disabilities. People with Down syndrome can expect to live more than 60 years, depending on the severity of their health problems.

Down syndrome can be diagnosed through blood tests, nuchal translucency tests, chorionic villus sampling (CVS), amniocentesis, and physical examination. Furthermore, management options for Down syndrome may include physical or occupational therapy, speech therapy, and participating in special education programs in school.

Similarities Between Mosaic Down Syndrome and Trisomy 21

1. Mosaic Down syndrome and trisomy 21 are two associated medical conditions.
2. Mosaic Down syndrome is a rare form of trisomy 21.
3. In both these conditions, there is an extra chromosome in the cells.
4. Both these conditions can be diagnosed through physical examination and screening tests.
5. They can be managed through special therapies.

Comparing the Difference Between Mosaic Down Syndrome and Trisomy 21

Definition

a. Mosaic Down syndrome is a rare form of Down syndrome in which individuals have two copies of chromosome 21 in some cells and three copies in others throughout the body.

b. Down syndrome, or trisomy 21, is a genetic disorder caused by an extra full or partial copy of chromosome 21 present in all cells of the body.

Life Expectancy

a. Individuals with Mosaic Down syndrome can live up to 80 years.

b. Individuals with trisomy 21 can expect to live more than 60 years, depending on the severity of their health problems.

Intellectual Disabilities

a. Mosaic Down syndrome is associated with a milder form of intellectual disability.

b. Trisomy 21 typically results in a more severe form of intellectual disability.

Symptoms

a. Symptoms of Mosaic Down syndrome include almond-shaped eyes that tend to slant upward, a shorter-than-average neck, a flattened face, small ears, white spots on the iris of the eye, poor muscle tone, loose joints, shorter height or slower growth, small hands and feet, small pinky fingers, and a tongue that sticks out of the mouth.

b. Symptoms of trisomy 21 include a flattened face, small head, short neck, protruding tongue, upward-slanting eyelids, unusually shaped or small ears, poor muscle tone, broad, short hands with a single crease in the palm, excessive flexibility, tiny white spots on the iris of the eye, short stature, and intellectual disabilities.

Diagnosis

a. Mosaic Down syndrome can be diagnosed through testing a sample of cells from the placenta or amniotic fluid, along with physical examination.

b. Trisomy 21 can be diagnosed through a blood test, nuchal translucency test, chorionic villus sampling (CVS), amniocentesis, and physical examination.

The following table summarizes the between Mosaic Down Syndrome and Trisomy 21.

Summary – Mosaic Down Syndrome vs Trisomy 21

A medical term for having an extra copy of a chromosome in the body cells is ‘trisomy.’ In both mosaic Down syndrome and trisomy 21 conditions, there is an extra chromosome in the cells. These conditions may share certain characteristics. However, people with mosaic Down syndrome only have an extra chromosome in some cells, while people with trisomy 21 have an extra chromosome in all of their cells. So, this summarizes the difference between mosaic Down syndrome and trisomy 21.

FAQ: Mosaic Down Syndrome and Trisomy 21

1. What is the difference between Down syndrome and mosaic?

• Down syndrome is a genetic disorder that occurs due to an extra copy of chromosome 21. Individuals with mosaic Down syndrome typically have a mixture of cells, with some containing two copies of chromosome 21 in body cells while others have three.

2. What happens in mosaic Down syndrome?

• Mosaic Down syndrome is caused by a random event shortly after the egg and sperm unite or fertilize. In this scenario, during cell division, some cells receive an extra copy of chromosome 21 while others have three copies.

3. Is mosaic Down syndrome curable?

• There is no cure for mosaic Down syndrome. The chromosomal abnormalities cannot be corrected or treated at any age, not even before birth. However, the effects on the body can be managed through therapies that can improve a person’s outcomes, quality of life, and life expectancy.

4. What is the life expectancy of a person with trisomy 21?

• Individuals with this type of Down syndrome can expect to live up to 60 years. In the 1940s, a child with Down syndrome had a life expectancy of 12 years. Nowadays, their life expectancy is around 60 years, in line with the general population.

5. Can trisomy 21 be cured?

• There is no cure for this form of Down syndrome, but management of the condition is available to help the child. The child may require physical, occupational, and speech therapy to aid in their development. Additionally, early intervention and special education services may be provided.

Reference:

1. Fergus, Kathleen. “Common Characteristics of down Syndrome.” Verywell Health.
2. “About down Syndrome.” National Down Syndrome Society (NDSS).

Image Courtesy:

1. “Young girl with Down’s syndrome, sitting, wearing striped so Wellcome V0030051” By Welcome Image Gallery (CC BY 4.0) via Commons Wikimedia

2. “Down Syndrome Karyotype” By National Human Genome Research Institute – Human Genome Project (Public Domain) via Commons Wikimedia