Background and Aim:-thalassemia is the most common inherited disorder of hemoglobin (Hb) synthesis in the world. Alpha thalassemia most frequently results from the loss of one (- ) or both (- -) of the duplicated  genes () on chromosome 16. Carriers of deletional forms of -thalassemia (-/- /-, or --/) are clinically normal but have a mild hypochromic, microcytic anemia. Compound heterozygotes (--/- ) called Hb H disease. Fetuses who inherit no  genes (--/--) (Hb Bart's Hydrops fetalis syndrome) die either inutero or shortly after birth, More than 95% of recognized -thalassemia involves deletion of one or both  globin genes on chromosome 16.

Materials and Methods: The assay was tested on 114 Iranian individuals with low MCV and MCH levels but normal HbA2 who had not responded to Iron treatment. patients was referred to the Department of Biotechnology, Pasteur Institute of Iran by Health Centers. Genomic DNA was isolated from white blood cells by salting out method. We have developed a reliable, single - tube multiplex polymerase chain reaction (PCR) assay for the 7 most frequent - thalassemia deletions (-- SEA , --THAI, --FIL , -α20.5 , --MED, -α4.2 , -α3.7).

Results: DNA fromd thalassemia carriers was tested for the presence of different types of  globin gene deletion (s). The - 3.7 and - 4.2 single gene deletions, and the Mediterranean (-- MED and - 20.5) double gene deletions were found in some samples.

Conclusion: The - 3.7 deletion was found to be the most common cause of  globin gene deletion in our samples. Multiplex PCR for α gene deletion analysis is simple, rapid and sensitive.