SCIENTIFIC BACKGROUND

HBA1, HBA2

Category:

SCIENTIFIC BACKGROUND

Alpha thalassemia is a result of a quantitative disorder of α-globin chain synthesis. The deficit of α-globin chains leads to the formation of excess hemoglobins which are significantly responsible for the clinical picture of alpha thalassemia. Like other hemoglobinopathies, the disease occurs more frequently in countries where malaria is endemic and is therefore associated with a certain resistance to plasmodia. Alpha thalassemia is particularly common in populations of Asia, Arabia, and Africa, as well as Mediterranean countries.

 

The most common molecular genetic cause of alpha thalassemia is the deletion of one or more α-globin genes. In normal human cells, the α-globin gene complex consists of 4 α-globin genes (one HBA1 and one HBA2 gene on each chromosome 16), therefore the severity of the clinical picture depends on the number of deleted α-globin genes. In rare cases, point mutations or minor deletions and insertions in the α-globin genes can also be causative for alpha thalassemia.

 

Most carriers of alpha thalassemia are diagnosed by chance during a routine examination. The blood count or sometimes also a lowered Hb value reveals a microcytosis and/or hypochromia. In the course of diagnosis, iron deficiency should first be ruled out by determining serum ferritin, which is the most common cause of microcytic hypochromic anemia. In advance, the Huber-Herklotz formula can already be used to estimate whether the diagnosis is more likely an iron deficiency anemia or an alpha thalassemia.

 

If iron deficiency has been ruled out, the presence of hemoglobinopathy can be investigated by Hb differentiation. In many cases, the question of a predisposing carrier of a hemoglobinopathy arises only in the context of conceiving a child, either because of a positive family history or because of ethnic origin. In the case of an already existing pregnancy, a rapid diagnosis is important in order to be able to assess the risk of a severe form of hemoglobinopathy in the offspring as early as possible.

 

Since hemoglobinopathies can occur in a wide variety of combinations, hematologic findings should always be compared with molecular genetics results and checked for validity.

 

References

Origa R, Moi P. Alpha thalassemia. 2005 Nov 1 [Updated 2016 Dec 29]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2019 / Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften. S1-Leitlinie: Thalassämie. 30.06.2016 / Kohne et Kleihauer 2010, Dtsch Arztebl Int 107:65 / Weatherall et Clegg 2001, The Thalassaemia Syndromes, 4th ed. Oxford: Blackwell Science / Kleihauer et al. 1996, Anomale Hämoglobine und Thalassämiesyndrome, ecomed Verlag

GENES

HBA1, HBA2

ASSOCIATED TESTS

How to order

LATEST ARTICLES

Exciting news in genetic research! The Human Pangenome Reference Consortium has unveiled an improved version of the human pangenome reference. This c...

Read more

Duchenne muscular dystrophy, a rare inherited muscle disorder characterized by progressive muscle weakness and degeneration that leads to difficultie...

Read more

May 12 is International Nurses Day. It is celebrated on Florence Nightingale’s birthday. She pioneered the field of modern nursing through her dedi...

Read more

Hair loss is a common problem that affects millions of men and women around the world. While genetics is believed to be the most significant factor c...

Read more

Depression is a serious mental health issue affecting over 280 million people worldwide. Recent research has revealed a potential link between gut he...

Read more

If you are unlucky enough to suffer from migraines, you will know that a migraine is not just a bad headache. The headache and accompanying symptoms ...

Read more

Autism spectrum disorder (ASD) is a neurological developmental disorder that affects brain development and function. This affects how people learn, b...

Read more

Researchers have developed a method called "Mendelian Phenotype Search Engine" (MPSE) to identify which sick infants in the neonatal intensive care u...

Read more

Did you know that wisdom teeth are actually an evolutionary leftover from our ancient ancestors that no longer serve their original purpose? These mo...

Read more

Azoospermia is a medical condition characterized by the absence of sperm in the ejaculate and is a major cause of male infertility. It affects 1 in 1...

Read more