The Influence of Polymorphisms in Disease Severity in β-Thalassemia.

β-Thalassemia is a genetic disorder with a continuum of mild to severe clinical manifestations and requirement of transfusion at different stages of life. The cause(s) of this variety is not clear but genetic alterations could be a potential factor. In this review, the correlation between polymorphisms and different clinical manifestations, including the need for transfusion, was investigated. Relevant articles published in pubmed database from 1982 onwards were studied and compiled. The articles all contained the keywords β-thalassemia, genetic modifiers, and mutations. Certain polymorphisms and mutations could dictate the severity of symptoms as well as their onset. A significant number of the mentioned genetic alterations appear in beta-globin gene cluster and affect gamma chain. Therefore, hemoglobin F production rate is increased and can affect thalassemia symptoms and can relieve β-thalassemia symptoms. A number of polymorphisms in catalase and glutathione S transferase genes have also been shown to modify the severity of disease and response to treatment. Knowledge of these mutations and polymorphisms can provide an insight into the prognosis for individual patients, especially in young ages or before birth to take proper measures in advance and eventually ameliorate the symptoms in the long run.