Thalassemia

toc =Thalassemia= By: Riley Whitham, Taylor Morris, and Andrew Meckel

Thalassemia is the most commonly inherited genetic disorder that effects the production of hemoglobin, which are oxygen carrying chemicals found in red blood cells. There are four main types of thalassemia: alpha, beta, major and minor. Major is a more severe case with more severe symptoms. Minor is just carrying the gene, still with symptoms but a lot less severe.(1)

Alpha and Beta Thalassemia
Every hemoglobin molecule has four subunit proteins, two called alpha, and two called beta. The hemoglobin only works correctly when two beta subunits are connected to two alpha subunits. A pair of genes on chromosome 16 control the production of the alpha subunits and a single gene on chromosome 11 controls the production of beta subunits. Beta thalassemia occurs when a beta globin gene fails, causing a shortage of beta subunits, which causes the hemoglobin to bind and release less oxygen. Alpha thalassemia occurs when an alpha globin gene fails, causing a shortage of alpha subunits. This also causes hemoglobin to bind and release less oxygen. Beta thalassemia is worse than alpha thalassemia, because there is a pair of genes controling the production of alpha subunits and a single gene controlling the production of beta subunits. This means there are four alpha globin genes controlling the production of alpha subunits rather than two beta globin genes controlling the production of beta subunits. The total number of alpha subunits is the same as the total number of beta subunits. This means one alpha globin gene produces half as many subunits as one beta globin gene produces. For this reason if one alpha globin gene fails it is not as bad as when one beta globin gene fails.(5)

Effects
In thalassemia major, there are two thalassemia genes inherited. There are no signs of the condition in infants at birth. If the child goes five years without any symptoms, there is little to no chance that the child will be diagnosed. If the child has symptoms, they may be diagnosed as infants. As they grow, infants with thalassemia exhibit paleness and fusiness. In addition, weakness and slow growth may also appear. Liver and spleen enlargement cause swelling of the abdomen, and face structure may be distorted. In order to live, someone diagnosed with thalassemia is required to receive blood transfusions every 4-6 weeks. Neither home nor school modifications are necessary, due to the fact that the disorder affects the body internally. Adults living with thalassemia have only the responsibility of maintaining blood health, by regularly receiving blood transfusions. (2)

Symptoms
The symptoms of Thalassemia are as follows: (1)
 * Paleness
 * Headaches
 * Fatigue
 * Shortness of Breath
 * Spleen and liver enlargment
 * Jaundice

Prognosis
Cases of thalassemia that are not as severe do not normally shorten a person's life span. Severe cases of thalassemia can cause death to people between the ages of 20 and 30. A death around this age would be caused by a heart failure (4).

Diagnosis
Thalassemia is diagnosed by blood tests taken by doctors. Severe thalassemia can normally be diagnosed in young children between the age of 0 and 2. Doctors can diagnose thalassemia by taking a CBC test, a Hemoglobin test, or by testing the amount of iron in someone's blood. A CBC test tells doctors the amount of hemoglobin in a sample of blood. Hemoglobin tests gives information on the types of hemoglobin in a blood sample (5).

Pattern of Inheritance
Thalassemia is a [|hereditary] [|recessive gene]. If both parents carry the gene, ther is a 1 in 4 chance that the child will have thalessemia major, a 2 in 4 chance that the child will carry the gene, and a 1 in 4 chance that the child will neither have the disease nor carry it. Major thalassemia tends to be more common in people with the following heritage:(2)
 * African
 * Middle Eastern
 * East Indian
 * Southeast Asian
 * Chinese
 * Occasionally Mediterranean

Punnett Square
||  T   ||   t   || ||  TT   ||   Tt   || ||  Tt   ||   tt   || T= Allele for thalassemia, t= regular Tt= Thallasemia carrier, TT= Thalssemia major, tt= regular There is a 1 in 4 chance that a child will not have the disease nor carry it.
 * Parents
 * T
 * t

Sample Problem
If a female carrier of thalassemia marries a male that doesn't have thalassemia what are the chances that their child will have thalassemia major?

Thalassemia Gene
In all types of thalassemia, there is a defect in the production of proteins in the hemoglobin. (1)

Treatment
As of today, there are no perscribed treatments to thalassemia. But occasionaly, a doctor may recommend taking iron medication if necessary. Regular blood transfusions, though, are also helpful. There have been no recent discoveries or advances in the study of thalassemia. (1)

Advantages
Thalassemia is not a helpful mutation. In fact, due to the blood transfusions and regular visits to the doctor's office, it is thought of as a disadvantage. There are no signs of an evolutionary advantage to having thalassemia. (7)

Discussion Question
Do you think that thalassemia is a serious disease that deserves as much attention as serious diseases such as cancer? Why?