Update in the genetics of thalassemia: What clinicians need to know.

Thalassemia is a significant health problem worldwide. Prenatal diagnosis is the only effective way to prevent the birth of a fetus with severe thalassemias, which include hemoglobin Bart's hydrops fetalis and thalassemia major. However, accurate prenatal diagnosis depends on the comprehensive consideration of the molecular basis of thalassemias. To make a correct decision, the obstetrician should have a certain understanding of the genetics of thalassemias. Here we present a brief introduction of some fundamental genetic knowledge of thalassemias, including the production of hemoglobin, structure and location of globin genes, hemoglobin switch, epidemiology, clinical classification, molecular and cellular pathology, genotype-phenotype correlation, and genetic modifiers. Furthermore, some unusual clinical cases that cannot be explained by Mendel's laws are described. On the basis of a thorough understanding of the above information, clinicians should have the ability to precisely diagnose thalassemia patients and provide applicable genetic counselling to the affected families.