WHAT IS DOWN SYNDROME

Via NoahsDad.com

If you are a new parent one of your first questions may be “What is Down syndrome?” 

Down syndrome (Trisomy 21) is a chromosomal abnormality where a child is born with three copies of the 21st chromosome (Just like in the picture!)

Chromosomes hold our genetic information, and there are 23 types of chromosomes. One set of those being your sex chromosomes (X, and Y), and the others labeled 1 through 22. When babies are created, they receive 23 chromosomes from their mom contained in her egg and 23 chromosomes from their dad contained in his sperm, totaling 46 chromosomes.

Children with Down syndrome are born with an extra 21st chromosome.

Three Types Of Down Syndrome:

1. Nondisjunction: This is the most common reason. Cells containing 46 chromosomes are split equally to create eggs and sperm, which then contain 23 chromosomes. Nondisjunction means that the cells did not equally divide the genetic information. This creates a sperm or egg that contains 24 chromosomes with two copies of the 21st chromosome. That egg/sperm joins with a typical egg/sperm with 23 chromosomes making a cell that has 47 chromosomes and three copies of the 21st chromosome. This is known as Trisomy 21. This is a random occurrence.
2. Translocation: The egg or sperm have 23 chromosomes, however part of the 21st chromosome has attached itself to one of the other chromosomes during the division processes that occur when the egg or sperm were made. Therefore, even though they have the right number of chromosomes there is actually extra 21st chromosome material. This CAN be (not always) an inherited condition, which can increase your risk of having another child with Down syndrome. Your doctor will want both parents to be tested to see if this is a possibility.
3. Mosaic: Not all of the cells are affected, so the baby would have cells with 46 chromosomes and also 47. This can occur in two ways. The baby either started with 46 chromosomes, however nondisjunction occurred with further cell division in only part of the cell lines creating some cells with three copies of the 21st chromosome. The other way is that the baby started out as trisomy 21 and nondisjunction occurred creating cells that now contain 46 chromosomes. This is a random occurrence.

NOT TWO BUT, THREE 21ST CHROMOSOMES

WHAT IS LEUKEMIA

Via MayoClinic.com

Scientists don't understand the exact causes of leukemia. It seems to develop from a combination of genetic and environmental factors.

How leukemia forms

In general, leukemia is thought to occur when some blood cells acquire mutations in their DNA — the instructions inside each cell that guide its action. There may be other changes in the cells that have yet to be fully understood could contribute to leukemia.

Certain abnormalities cause the cell to grow and divide more rapidly and to continue living when normal cells would die. Over time, these abnormal cells can crowd out healthy blood cells in the bone marrow, leading to fewer healthy white blood cells, red blood cells and platelets, causing the signs and symptoms of leukemia.

How leukemia is classified

Doctors classify leukemia based on its speed of progression and the type of cells involved.

The first type of classification is by how fast the leukemia progresses:

  • Acute leukemia. In acute leukemia, the abnormal blood cells are immature blood cells (blasts). They can't carry out their normal functions, and they multiply rapidly, so the disease worsens quickly. Acute leukemia requires aggressive, timely treatment.
  • Chronic leukemia. There are many types of chronic leukemias. Some produce too many cells and some cause too few cells to be produced. Chronic leukemia involves more mature blood cells. These blood cells replicate or accumulate more slowly and can function normally for a period of time. Some forms of chronic leukemia initially produce no early symptoms and can go unnoticed or undiagnosed for years.

The second type of classification is by type of white blood cell affected:

  • Lymphocytic leukemia. This type of leukemia affects the lymphoid cells (lymphocytes), which form lymphoid or lymphatic tissue. Lymphatic tissue makes up your immune system.
  • Myelogenous (my-uh-LOHJ-uh-nus) leukemia. This type of leukemia affects the myeloid cells. Myeloid cells give rise to red blood cells, white blood cells and platelet-producing cells.

How leukemia is classified

Doctors classify leukemia based on its speed of progression and the type of cells involved.

The first type of classification is by how fast the leukemia progresses:

  • Acute leukemia. In acute leukemia, the abnormal blood cells are immature blood cells (blasts). They can't carry out their normal functions, and they multiply rapidly, so the disease worsens quickly. Acute leukemia requires aggressive, timely treatment.
  • Chronic leukemia. There are many types of chronic leukemias. Some produce too many cells and some cause too few cells to be produced. Chronic leukemia involves more mature blood cells. These blood cells replicate or accumulate more slowly and can function normally for a period of time. Some forms of chronic leukemia initially produce no early symptoms and can go unnoticed or undiagnosed for years.

The second type of classification is by type of white blood cell affected:

  • Lymphocytic leukemia. This type of leukemia affects the lymphoid cells (lymphocytes), which form lymphoid or lymphatic tissue. Lymphatic tissue makes up your immune system.
  • Myelogenous (my-uh-LOHJ-uh-nus) leukemia. This type of leukemia affects the myeloid cells. Myeloid cells give rise to red blood cells, white blood cells and platelet-producing cells.

 

Types of leukemia

The major types of leukemia are:

  • Acute lymphocytic leukemia (ALL). This is the most common type of leukemia in young children. ALL can also occur in adults.
  • Acute myelogenous leukemia (AML). AML is a common type of leukemia. It occurs in children and adults. AML is the most common type of acute leukemia in adults.
  • Chronic lymphocytic leukemia (CLL). With CLL, the most common chronic adult leukemia, you may feel well for years without needing treatment.
  • Chronic myelogenous leukemia (CML). This type of leukemia mainly affects adults. A person with CML may have few or no symptoms for months or years before entering a phase in which the leukemia cells grow more quickly.
  • Other types. Other, rarer types of leukemia exist, including hairy cell leukemia, myelodysplastic syndromes and myeloproliferative disorders.

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