The clinical severity of beta-thalassemia mutations in West Malaysia.
Beta-thalassemia in West Malaysia is caused by 14 molecular defects with differing clinical severity. In Chinese patients from West Malaysia, the main beta-thalassemia mutations seen were (a) a 4 base pair-TCTT deletion in codon 41-42 [frameshift mutation (FSC 41-42)]; (b) a C to T substitution at the second intervening sequence (IVS2-654); (c) an A to G substitution in the TATA box [-28 (A to G)], and (d) an A to T substitution in codon 17[17 A to T]. In the Malays, the main mutations seen were (a) a G to C in nucleotide 5 at the intervening sequence I [IVS1-5 (G to C)]; (b) G to T substitution in nucleotide I at the intervening sequence I [IVS1-1 (G to T)]; (c) a A to T substitution in codon 17 (17 A to T); (d) removal of C from codon 35 [codon 35 (-C)], and (e) a 4 base pairs-TCTT deletion in codon 41-42 [frameshift mutation (FSC 41-42)]. A scoring system (Tha1 CS) has been formulated to predict clinical severity. It is the type of beta-thalassemia mutation present that decides on the clinical phenotype. The most severe beta-thalassemia mutation is assigned a score of 4. A score of 8 indicates severe thalassemia.
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Department of Pathology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia.
D002681:China / Q000208:ethnology; D003062:Codon; D016368:Frameshift Mutation; D005914:Globins / Q000235:genetics*; D006801:Humans; D007438:Introns; D008296:Malaysia; D010641:Phenotype; D017354:Point Mutation; D017384:Sequence Deletion; D017086:beta-Thalassemia / Q000235:genetics* / Q000503:physiopathology*
D003062:Codon; D005914:Globins