History of hemoglobinopathies and prenatal diagnosis in Iran: report of 1141 cases

ABSTRACT

Hemoglobin is the first polypeptide that showed a direct relation between the gene and its product. Hemoglobin is a tetramer composed of a couple of different globin chains surrounding the heme nucleus. In addition to different original hemoglobin, according to the point changes in the globin genes, different hemoglobin molecules may be formed, but almost similar to original hemoglobin. This may be a polymorphism phenomenon. Some of these point mutations result in abnormal hemoglobin such as HbS and HbC which causes sickle cell anemia and hemoglobin C disease. In a healthy human; there are three kinds of hemoglobin designated as HbA[1][97%] A[2] [3%] and F [0.3%] composed of alpha2 beta2, alpha2, and alpha2lambda2 respectively. Mutation on a or beta chain gene may result to abnormal hemoglobins causing mild to severe disorders. These disorders are frequent in the Mediterranean and Middle East countries. The first prenatal diagnosis [PND] for thalassemia was performed in 1972 and improving very well. The first PND for thalassemia in spite of lots of problems has been done in our country at 1990, and then later on a national prevention net has been established working very well, which could be a good model for neighbor countries. According to the different genes and their frequencies over the country; we divided the country to eight parts. Upon the gene frequencies, 23 mutations of beta globin and 21 mutations of alpha globin gene has been detected. So far, we believe that there are still some other mutation genes, as well. We are reporting the result 1141 PND of hemoglobinopathies. In our study 23.2% of fetuses were normal, 48.3% were minor thalassemia and 23.2% were affected bearing major beta thalassemia. In 2.8% of cases; we were able to detect one normal allele, therefore fetuses may be normal or minor thalassemia. In 0.9% only one mutant gene has been detected, thus fetus may be major or minor thalassemia. We were unable to identify none of genes in 0.9% cases