What is sickle cell anemia?

 Sickle cell anemia

Introduction

People with African heritage are more likely to suffer from the hereditary condition known as sickle cell anemia. The disease is inherited as an autosomal recessive characteristic and is brought on by mutations in one of the genes that code for the hemoglobin protein. Red blood cells with the mutation have a unique sickle shape. People who have sickle cell disease are persistently anemic and suffer serious heart, lung, and kidney damage.

Inheritance

Inheritance of sickle cell anemia

Sickle cell anemia is inherited from parents in an autosomal recessive manner. The hemoglobin genes that a person inherits from her or his parents determine the forms of hemoglobin that person produces in her or his red blood cells. A child has a 50% probability of having sickle cell illness and a 50% chance of having sickle cell trait if one parent has sickle cell anemia and the other has sickle cell trait. A kid has a 25% probability of developing sickle cell disease when both parents have the trait; 25% do not contain any sickle cell genes, and 50% are heterozygous.

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Mutation

The -globin gene has a single nucleotide mutation (GAG codon changing to GTG) that causes glutamate to be replaced by valine at position 6. In contrast to adult HbA, hemoglobin S with this mutation is referred to as HbS. In  situations of normal oxygen concentration,

Mutation causing sickle cell anemia

this mutation is typically benign, having no discernible impact on the secondary, tertiary, or quaternary structures of hemoglobin. The deoxy form of hemoglobin exposes a hydrophobic patch on the protein between the E and F helices, which causes HbS to polymerize and produce fibrous precipitates under low oxygen concentration

Symptoms

Following are some symptoms of sickle cell anemia

Ø  Anemia.

Sickle cells easily disintegrate and expire. Red blood cells typically last 120 days or so before needing to be replaced. However, a lack of red blood cells results from sickle cells, which normally expire in 10 to 20 days (anemia). Fatigue results from the body's inability to obtain enough oxygen if there are not enough red blood cells.

Ø  Hands and foot swelling.

Sickle-shaped red blood cells obstructing blood flow to the hands and feet are to blame for the edema.

Ø  Recurring infections

The spleen may become damaged by sickle cells, making it more susceptible to infections. Antibiotics and immunizations are frequently given to infants and kids with sickle cell anemia to help them avoid potentially fatal illnesses like pneumonia.

Ø  Delayed puberty or growth

The oxygen and nutrients the body needs for growth are delivered by red blood cells. Lack of healthy red blood cells can prevent teens from going through puberty and slow down newborns' and children's growth.

Ø  Vision issues.

Sickle cells can clog the tiny blood arteries that supply the eyes. This could harm the retina, the area of the eye responsible for processing visual pictures, and cause vision issues.

Vision problems

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Diagnosis

Following are few tests that can be used to test onset of sickle cell anemia.

Ø Screening

It has proved very helpful in determining the diseases.

·       Newborn screening

In some regions it is mandatory to screen newborn baby. This help in early treatment of diseases.

·       Carrier screening

To determine whether parents are carrier for disease or not. If both parents have a defective gene for disease then there are more chances that offspring will have the disease.

Ø Complete blood count (CBC)

It is done to count number of different types

CBC

of blood cells in our blood. This helps in determining the number of RBCs. Low number of RBCs helps to guess sickle cell anemia.

Ø Hemoglobinopathy (Hb) evaluation

This test is used to measure and distinguish different types of hemoglobin in subject’s body. Following methods are used to do so;

Hemoglobin electrophoresis

Mass spectrometry

Genetic testing through DNA analysis in which DNA sequencing is done

Ø Blood smear

This is done manually, in which thin layer of blood is examined under microscope and, quantity and quality of RBCs is determined.

Ø Iron studies

This test is performed to assess body’s iron storage and usage. Patients with diseases had received multiple blood transfusions which may lead to iron over loading.

Risk factors

People with following attributes are at greater risk to fell prey of disease than others;

·       If they have African ancestry

·       If they have excessive malaria in there region

·       If they work or live somewhere, where mutation causing agents are present more than normal. i. e x-rays, nuclear radiations, or some other agents.