Thalassemia sentence example
A child may inherit thalassemia trait when only one parent has the genes responsible for it.
An inherited form of hemolytic anemia, thalassemia comes from the production of abnormal hemoglobin.
Thalassemia has several types that involve imbalances in the four chains of amino acids that comprise hemoglobin (alpha- and beta-globins).
In thalassemia minor or thalassemia trait (heterozygous thalassemia), also called alpha-thalassemia, there is an imbalance in the production of the alpha chain of amino acids.
In thalassemia minor, fetal hemoglobin (HbF), the hemoglobin form that circulates in the fetus, does not decrease normally after birth and may remain high in later life.Advertisement
Thalassemia major (homozygous thalassemia or Cooley's anemia) occurs in children in whom both parents pass on the genes responsible.
Hemoglobin H disease is another form of thalassemia in which three of the four beta-globin genes are missing.
Thalassemia occurs in four out of 100,000 individuals in the United States, particularly among those of Mediterranean, Asian, or middle Eastern descent.
Diagnosing thalassemia and sickle cell anemia, both of which involve disorders of hemoglobin, will require measuring the different types of hemoglobin through a laboratory testing method called hemoglobin electrophoresis.
Thalassemia minor is typically not treated.Advertisement
Thalassemia major may be treated with regular transfusions, surgical resection of the spleen to avoid its removal of RBCs from circulation, and sometimes iron chelation therapy.
Children or young adults with thalassemia major may require periodic hospitalization to receive blood transfusions or, in some cases, bone marrow transplants.
Thalassemia major may cause deformities and may shorten life expectancy.
Thalassemia describes a group of inherited disorders characterized by reduced or absent amounts of hemoglobin.
In all types of thalassemia, the quantity of hemoglobin produced is reduced or absent.Advertisement
The two diseases are quite different from beta thalassemia, as well as from one another.
Hemoglobin H disease is milder than alpha thalassemia and usually milder than beta thalassemia.
Individuals with alpha thalassemia major have inherited two completely defective genes, one from each parent.
Alpha thalassemia major, sometimes called hemoglobin Barts or hydrops fetalis, is a fatal disease that results in severe anemia that begins even before birth.
Beta thalassemia, also called Cooley's anemia, is the most well known type of thalassemia.Advertisement
Beta thalassemia causes variable anemia that can range from moderate to severe, depending in part on the exact genetic change underlying the disease.
Beta thalassemia major causes severe anemia that usually occurs within three to six months after birth.
In developed countries, screening in the newborn period usually identifies beta thalassemia before symptoms have developed.
Beta thalassemia minor describes a disease where only one gene of the pair that control beta hemoglobin production is defective.
Beta thalassemia intermedia is a clinical term that describes the disease in individuals who have moderate anemia that only requires blood transfusions intermittently.Advertisement
Both alpha and beta thalassemia have been described in individuals of almost every ancestry, but the conditions are more common among certain ethnic groups.
Unaffected carriers of all types of thalassemia traits do not experience health problems.
Determining the prevalence for alpha thalassemia is difficult due to limitations in diagnostic testing.
In the United States, up to 30 percent of African Americans are thought to be carriers for alpha thalassemia traits, meaning that they show no symptoms of the disorder but can pass the trait to their offspring.
Despite this estimate, the number of babies born with hemoglobin H disease or alpha thalassemia major is very low.Advertisement
The highest frequency of alpha thalassemia diseases occurs in individuals of Southeast Asian and Chinese descent.
One study of 500 pregnant women in northern Thailand estimated a frequency of one in 500 pregnancies affected by alpha thalassemia major, for example.
Prevalence of alpha thalassemia disease is significantly lower in the United States owing primarily to immigration patterns.
It is difficult to obtain accurate prevalence figures for various types of thalassemia within different populations.
Two studies reflect prevalence figures that can be helpful counseling families and determining who to screen for beta thalassemia.Advertisement
Between the years of 1990 and 1996, the State of California screened over 3.1 million newborns for beta thalassemia.
Approximately one in 114,000 infants had beta thalassemia major, with prevalence rates being highest among Asian Indians (about one in 4,000), Southeast Asians (about one in 10,000), and Middle Easterners (about one in 7,000).
All types of thalassemia are caused by changes in either the alpha- or beta-globin gene.
The severity of the disease is influenced by the exact thalassemia mutations inherited, as well as other genetic and environmental factors.
There are rare exceptions, notably with beta thalassemia, where globin gene mutations exhibit a dominant pattern of inheritance in which only one gene needs to be altered in order to see disease expression.Advertisement
Absence of one functioning alpha globin gene leads to a condition known as silent alpha thalassemia trait.
Alpha thalassemia trait occurs when two alpha globin genes are missing or not functioning.
Hemoglobin H symptoms can also be a part of a unique condition called alpha thalassemia mental retardation syndrome.
Alpha thalassemia major results from the deletion of all four alpha globin genes, such that there are no functioning alpha globin genes.
In this situation, there is a 25 percent chance for alpha thalassemia major in each of such a couple's children.Advertisement
There are approximately one hundred genetic mutations that have been described that cause beta thalassemia, designated as either beta0 or beta+ mutations.
When an individual has one normal beta globin gene and one with a beta thalassemia mutation, he or she is said to carry the beta thalassemia trait.
Carrying the trait is generally thought not to cause health problems, although some women with beta thalassemia trait may have an increased tendency toward anemia during pregnancy.
When both parents carry the beta thalassemia trait, there is a 25 percent chance that each of their children will inherit beta thalassemia disease by inheriting two beta thalassemia mutations, one from each parent.
The clinical severity of the beta thalassemia disease depends largely on whether the mutations inherited are beta0 thalassemia or beta+ thalassemia mutations.Advertisement
Two beta0 mutations generally lead to beta thalassemia major, and two beta+ thalassemia mutations generally lead to beta thalassemia intermedia, a milder form of the disease.
Inheritance of one beta0 and one beta+ thalassemia mutation tends to be less predictable.
Hemoglobin H disease is a relatively mild form of thalassemia that may go unrecognized.
Beta thalassemia major is characterized by severe anemia that can begin several months after birth.
In the United States and other developed countries beta thalassemia is identified and treated early and effectively.
If untreated, beta thalassemia major can lead to severe lethargy, paleness, and growth and developmental delay.
This factor allows for treatment with blood transfusion therapy, which can prevent most of the complications of the severe anemia caused by beta thalassemia major.
Individuals with beta thalassemia intermedia have a more moderate anemia that may only require treatment with transfusion intermittently, such as when infections stress the body.
As a person with beta thalassemia intermedia gets older, however, the need for blood transfusions may increase to the point that they are required on a regular basis.
When this occurs the disease becomes more similar to beta thalassemia major.
Signs of thalassemia diseases are often noted by the doctor during newborn screening.
Diagnosis of thalassemia can occur under various circumstances and at various ages.
Several states offer thalassemia screening as part of the usual battery of blood tests done on newborns.
Thalassemia can be identified before birth using prenatal diagnosis.
Pregnant women and couples may choose prenatal testing in order to prepare for the birth of a baby that may have thalassemia.
Thalassemia may be suspected if an individual shows signs that are suggestive of the disease.
A complete blood count will identify low levels of hemoglobin, small red blood cells, and other red blood cell abnormalities that are characteristic of a thalassemia diagnosis.
Since thalassemia trait can sometimes be difficult to distinguish from iron deficiency, tests to evaluate iron levels are important.
Hemoglobin electrophoresis results are usually within the normal range for all types of alpha thalassemia.
Hemoglobin electrophoresis can also detect structurally abnormal hemoglobins that may be co-inherited with a thalassemia trait.
This test can be performed to help confirm the diagnosis and establish the exact genetic type of thalassemia.
Otherwise, the medical outlook is similar to a child with beta thalassemia major, with the important exception that ongoing, lifelong blood transfusions begin at birth.
Individuals with beta thalassemia major receive regular blood transfusions, usually on a monthly basis.
Overall, however, transfusion and desferoxamine therapy have increased the life expectancy of individuals with the most severe types of beta thalassemia major to the fourth or fifth decade.
It is, however, possible to identify carriers of the disease and provide them with genetic counseling and appropriate information concerning the chance of their offspring having thalassemia disease.
Higher-than-normal levels of fetal hemoglobin can ameliorate some of the symptoms of thalassemia.
This occurs in many diseases, including iron deficiency anemia, thalassemia (an inherited disease in which globin chain production is deficient), and anemias associated with chronic infection or disease.
For example, thalassemia minor and iron deficiency anemia are both microcytic and hypochromic anemias, and overlap in MCV and MCH.
However, iron deficiency anemia has an abnormally wide RDW, but thalassemia minor does not.