SICKLE CELL ANEMIA

Nada Mohamed Ahmed ,

MD, MT (ASCP)i

HEMOLYTIC ANEMIA

1. Membrane defects

- Hereditary spherocytosis

- Hereditary elliptocytosis

- Hereditary pyropoikilocytosis

- Hereditary stomatocytosis

2. Enzyme defects

-G6PD

3. -Hemoglobin defects -.Hemoglbinopathies(sickle

cell disorders) - Hb SS, CC, SC & S-B-

- Thalassemias

NON-IMMUNE

1. Hypersplenism

2. Infections (Malaria),,

3-mechanical trauma to RBCs

4. Liver dz (Spur cell)

AUTO-IMMUNE

1. Warm Ab

2. Cold Ab

3. Transfusion reactions

4. Drug associated

ExtracorpuscularOUTSIDE THE RED CELL

Intracorpuscular

WITHIN THE RED CELL

Hereditary Acquired

Membrane defects

PNH

OBJECTIVES

Definition Causes and Genetics design ClassificationPathogenesis Lab diagnosis

What is Sickle cell Disease

Sickle Cell disease: is a genetic disorder that affects erythrocytes (RBC) causing them to become sickle or crescent shaped.

The effects of this condition due to an abnormality of the hemoglobin molecules found in erythrocytes.

The change in cell structure arises from a change

inthe structure of hemoglobin.

A single change in an amino acid causes hemoglobin

to aggregate.

The origin of Sickle Cell anemia

• It’s autosomal recessive blood

disease.• You inherit it from your

parents.*The gene defect is a known mutation of a

single nucleotide.

*The person who receives only one

defective gene from either one of his parents will develop Sickle-cell

trait.

*The person that receives the defective

gene from both his parents will develop Sickle-cell disease.

Genetics design

Causes Sickle Cell

Is caused by a point mutation in the β-globin chain of haemoglobin, causing the amino acid glutamic acid to be replaced with the c amino acid valine at

the sixth position.

Types of Hemoglobin

Normal

Hb A

Hb A2

Hb F

Abnormal (350)

Hb S

Hb C

Hb E

Normally, humans have

Of these, Haemoglobin A makes up around 96-97% of the normal haemoglobin in humans.

Haemoglobin

A two alpha two beta

A2 two alpha two delta

F two alpha two gamma

Classification Sickle Cell Disease

Hemoglobin SS Disease

Hemoglobin SC Disease

Sickle Cell Trait

Common types of Sickle Cell DisordersType of anaemia

Hemoglobin variation

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Sickle Cell Anemia

Sickle haemoglobin (HbS) + Sickle haemoglobin

Most Severe – No HbA

Hemoglobin S-C disease

Sickle haemoglobin (HbS) + (HbC)

Mild form of Sickle Cell Disorder

Sickle Cell Trait Sickle haemoglobin (S) + Normal haemoglobin (A)

Classification

Sickle Cell Anemia vs. Sickle Cell Trait

People who have sickle cell anemia are born with it; means inherited, lifelong condition.They inherit two copies of sickle cell gene, one from each parent.Sickle cell trait is different from sickle cell anemia. People with sickle cell trait don’t have the condition, but they have one of the genes that cause the condition. People with sickle cell anemia and sickle cell trait can pass the gene on when they have children.

Sickle Cell Trait

Sickle haemoglobin (S) + Normal haemoglobin (A) in RBC

• Adequate amount of normal Hb (A) in red blood cellsRBC remain flexible CarrierDo Not have the symptoms of the sickle cell disorders, with exceptions:

Pain when Less Oxygen than usual

Minute kidney problems

Mechanism of Pathogenesis

When sickle hemoglobin (HbS) gives up its oxygen to the tissues, HbS sticks together

– Forms long rods form inside RBC – RBC become rigid, inflexible, and sickle-

shaped– Unable to squeeze through small blood

vessels, instead blocks small blood vessels– Less oxygen to tissues of body

RBCs containing HbS have a shorter lifespan

– Normally 20 days– Chronic state of anaemia

Red Blood Cells from Sickle Cell AnemiaDeoxygenation of SS erythrocytes leads to intracellular hemoglobin polymerization, loss of deformability and changes in cell morphology.

OXY-STATE DEOXY-STATE

Diagnosis

Sickle test

solubility testshemoglobin

electrophoresis test

Screening test for newborns DNA Analysis

Complete blood count

Laboratory investigations

Complete blood count

Level of Hb -: 6–8 g/dL (Normal range-: Male=13.5-17.5g/dl Female=11.5-15.5g/dl) High reticulocyte count (10–20%).

Blood film

The blood film is microcytic and hypocromicSickled cell anaemia Normal

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Sickling TestMethod:

1) A sample of venous blood or capillary blood may be collected for this test.

2) Mixing blood with the reducing agent, sodium metabisulphite, will induce sickling in susceptible cells.

3) the results can be viewed under a microscope after 20 minutes.

Normal RBC

Sickled RBC

Positive TestHbS

Negative TestHbA

This test is simple and quick, used to identify the

presence of HbS.

Sickle Solubility Test (SST)

Method

• A rapid and inexpensive technique used to screen for the presence of sickling hemoglobins, can be used at home.

• A positive result must be confirmed by another method (HPLC or electrophoresis) to confirm the presence of Hb S and to distinguish

Hb AS (carrier state) from Hb SS (sickle cell disease).• Disadvantage: Other insoluble hemoglobins, such as Hb C-Harlem,

will also give a positive result.1) Erythrocytes are lysed by saponin.

2) The released hemoglobin is reduced by sodium hydrosulfite in a phosphate buffer.

3) Reduced HbS is characterized by its turbidity ( insolubility).

The resulting tactoids of HbS causes the solution to

remain turbid.

The presence of HbA under these same

conditions results in a clear red solution.

Sickle Solubility Test (SST

Hemoglobin Electrophoresis test

* Haemoglobin electrophoresis will differentiate between homozygous and heterozygous conditions.

* Hemoglobin types have different electrical charges and move at different speeds.

*HbSS: Is less negative by 2

compared to HbA .

Migrates slower than HbA

*HbAS: Has both HbA and HbS.

Shows 2 bands

DNA analysis

• This test is used to investigate alterations and mutations in the genes that produce

hemoglobin components.

• It may be performed to determine whether someone has one or two copies of the Hb S

mutation or has two different gene mutations.

• Genetic testing is most often used for prenatal testing:

• amniocentesis “14 to 16 weeks”.

ScreeningPrenatal Testing

Amniocentesis 16 and 18 weeks of the pregnancy small risk of causing a miscarriage (1 in 100)

Signs and Symptoms of

Sickle Cell Anemia

Jaundice

Pain Episodes

AnemiaInfections

Ulcers on the Legs

Eye Problems

What Are the Signs and Symptoms of Sickle Cell

Anemia?The signs and symptoms of sickle cell anemia vary. Some people have mild symptoms. Others have very severe symptoms and often are hospitalized for treatment.

Sickle cell anemia is present at birth, but many infants don’t show any signs until after 4 months of age.

The most common symptom of anemia is fatigue (feeling tired or weak). Other signs and symptoms of anemia include:

• Shortness of breath• Dizziness• Headache• Coldness in the hands and feet• Pale skin• Chest pain

Signs and Symptoms Related to Anemia

What Are the Signs and Symptoms of Sickle Cell Anemia?

Signs and Symptoms Related to Pain

Sudden pain throughout the body is a common symptom of sickle cell anemia. This pain is called a "sickle cell crisis." Sickle cell crises often affect the bones, lungs, abdomen, and joints.

A sickle cell crisis occurs when sickled red blood cells form clumps in the bloodstream. (Other cells also may play a role in this clumping process.) These clumps of cells block blood flow through the small blood vessels in the limbs and organs. This can cause pain and organ damage.