Molecular Basis and prenatal diagnosis of B- Thalassemia in Southeast if Iran

Background and purpose : bata thlassemia is the most common monogenic disorders in Iran. The gene frequency varies the country. Sistan and Baluchistan province, located in the southeast of iran with more than 1200 affected individuals, represents one of the regions where thalassemia id not only an important public health problem but also a socioeconomic problem. As a matter of fact high frequency of ß- thalassemia gene inter- family marriages, evasion of couples to carry out pre- marriage blood test, avoidance of counseling before wedding and eagerness for more children in spite of having ß - thalassemia kids collectively prompted us to eatablish prenatal diagnostic center in khordad 1381(May 2002) in this province.Materials and methods : 140 minor thalassemia couples were referred to our center from May 2002 to Feb. 2004. After admission of the couples to the center their demographic data were collected. 10 ml of blood sample was then collected from couples added with anti- coaqulant(0.5 M EDTA). DNA was subsequently extracted before being amplified by Refractory Mutation System(ARMS) techniques vs the common primers of B- gene mutations in Iran. Within the 10 to 12th weeks of pregnancy, chorionic villi samples were taken and subjected onto two techniques namely direct and indirect. We afterwards evaluated the inheritance of mutation in the fetus from any of his/ her parents.Results : We carried out preliminary diagnosis for 56 couples, as well as first round and further step of prenatal diagnostic procedures for another 84 couples(n= 140). 79. 3% of the total number resided in cities, whereas 87.9% were born in Sistan and Baluchistan province. Out of which 30% and 70% had sistany and Baluchi ethnicity respectively. Furthermore, 60.7% had at least one affected child, while 85.7% had consanguineous marriages. Out of the totalnumber, 57.9% were from Sunni minority. 88.05% of the couples demonstrated one of the common mutations identified in Iran. The latter figure also indicted that IVS 1-5 was the most common mutation in this region as 77.9% of the sufferers carried the gene. Futher investigations on 84 couples by chorionic vili DNA analysis showed that, 21.4% of their fetuses had major thalassemia.Conclusion : High rate of homogeneity in mutations observed in this region has been caused by frequent inter- family marriages. Considering the population of Shiites and Sonis(40% & 60% respectively) both sects of religions with the same percentage stated above has made use of PND services in our center. It is worthy of mention that it is for the first the sonnies are willing to use prenatal diagnosis services. The establishment of this center in Zahedan has been one of the effective polices in prevention of thalassemi