Thalassemia Spectrum and Prenatal Diagnosis among Voluntary Couples in Shushtar City, during a Five Year Period

Abstract

Background: Thalassemia and other hemoglobinopathies are inherited disorders that result from genetic defects causing deficient synthesis of hemoglobin polypeptide chains. This study was done to determine the prevalence and to study the complete spectrum of alpha and beta thalassemia gene mutations in the voluntary hemoglobinopathy carrier couples-to-be referred to health centers of Shoushtar city, located in the north Khuzestan province. Methods: Subjects referred to health centers of the city of Shoushtar during 2011 - 2016 were evaluated for the presence of thalassemia minor. After that, alpha and beta thalassemia gene mutations were explored in suspected couples. The samples that underwent PND and diagnosing of causative mutational genes by chorionic villus sampling (CVS) through amniocentesis plus direct or indirect genetic testing at first trimester of pregnancy were proved to be a carrier for alpha thalassemia, beta thalassemia, or other hemoglobinapathies. Results: The mutations for 111/165 (67%) of beta thalassemia chromosomes (19 different mutations) were identified. Of which, IVSII-1 (G > A) and CD 36 - 37 (-T) mutations showed the highest frequency (23.4 for each one) followed by IVSI-110 (G > A) (10%), CD 82-83 (-G) (9%), and -110 (C > T) (7.2%). Among the alpha thalassemia subjects (54/165 (33%)), the -α3.7 mutation was the most common (79/6%) determinant identified in the city of Shoushtar. From 48 voluntary carrier couples who underwent PND, 10 (20.8%) couples were proved to have fetuses with major beta thalassemia; pregnancy termination was done for them. Conclusions: These data suggest that the spectrum of mutations in the city of Shoushtar differs from those reported from other parts of Iran. Therefore, in order to save the time and cost, it is recommended that for the prenatal diagnosis of thalassemia in the city of Shoushtar, analysis of common mutations should be considered as a front line screening strategy. Prenatal diagnosing in this survey demonstrated that beta thalassemia was the most common accounting for all disorders.