Common alpha-thalassemia deletions in transfusion-dependent thalassemia patients in the Southeast Asia region of Myanmar.

Screening of 3 common alpha-thalassemia (thal) deletions (-alpha3.7, -alpha4.2 and --SEA) in Southeast Asia was done by polymerase chain reaction in 170 unrelated Myanmar thal patients receiving transfusions. Thal deletions were detected in 27 patients (15.9%) as: (1) alpha-thal-2 (-alpha3.7/alphaalpha) in 12 heterozygous or hemoglobin (Hb) E-beta-thal cases; (2) alpha-thal-1 in 7 patients (2-alpha3.7/-alpha3.7 and 5 --SEA/alphaalpha); and (3) Hb H (-alpha3.7/--SEA) in 8 patients. The latter 15 alpha-thal-1 and Hb H patients had no beta-thal mutations and represented 8.8% of the overall patients seeking transfusion for refractory anemia in Myanmar. This is the first description of alpha-thal in Myanmar from the molecular aspect, and its clinical and racial heterogeneity are described and discussed.