Types of alpha+ thalassemia in Southeast Asia refugees.
We have determined alpha+ deletional thalassemia among 143 Southeast Asia refugees (Cambodians, Laotians, and Vietnameses). Gene frequency of alpha+ deletional thalassemia in Vietnameses (0.035) was found lower than in Cambodians and Laotians (0.11). Bam H1 and Bg1 II analysis indicated that both rightward and leftward thalassemias are encountered, the -alpha 3,7 form is being by far more frequent than the -alpha 4.2 one. Only type I cross-over was found by Apa I digestion on -alpha 3.7 chromosomes. The Rsa I polymorphism, 5' to Z alpha 2 block, is associated with -alpha 3.7 type I haplotype and the site is present in 12 out of 23 chromosomes. All these data suggest at least three origins of alpha+-thalassemia in Cambodia and Laos.
Dodé
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C
INSERM U 15, CHU Cochin, Paris.
Labie
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D
Rochette
J
J
D001210:Asia, Southeastern / Q000208:ethnology; D002872:Chromosome Deletion; D005787:Gene Frequency; D006239:Haplotypes; D006801:Humans; D011110:Polymorphism, Genetic; D013789:Thalassemia / Q000453:epidemiology / Q000235:genetics*