Potential of denaturing gradient gel electrophoresis for scanning of beta-thalassemia mutations in India

Over the last few years, substantial progress has been made in developing s trategies for the detection and characterization of various mutations causi ng beta-thalassemia. The Indian population comprises of numerous endogamous caste groups and beta-thalassemia is seen in almost all of them. Knowledge of the spectrum of beta-thalassemia mutations in the population is a prere quisite for successful implementation of a prevention programme. Among the different approaches available today, Denaturing Gradient Gel Electrophores is (DGGE) offers a valid technical approach which is applicable for screeni ng of known mutants and polymorphisms as well as in locating regions of DNA bearing unknown mutations. We analysed 356 unrelated beta-thalassemia heterozygotes by DGGE and detect ed 30 anomalous DGGE patterns. Fifteen mutations were characterized after s equencing 25 anomalous patterns. Of these, codon 10(GC (C) under bar --> GC (A) under bar) is a recently reported novel beta-thalassemia mutation whil e -28(A --> G) and codon 121(G --> T) are being reported for the first time in the Indian population. HbS and HbE also showed two anomalous DGGE patte rns each. Framework (FW) linkage studies showed that four mutations were as sociated with different beta-globin gene frameworks. Linkage of IVSI-5(G -- > C) and cap site +1 (A --> C) to FW2 and 619-bp deletion to FW1 is being o bserved for the first time. Multiple DGGE patterns corresponding to the same mutation is one of the maj or drawbacks of this technique. In spite of this, if sufficient preliminary work has been carried out to compile a comprehensive catalogue of DGGE pat terns; this is a powerful approach to characterize the mutation or to local ize a small region of DNA in the case of rarer mutations. Am. J. Hematol. 6 1:120-125 1999. (C) 1999 Wiley-Liss, Inc.