Objective: To report the result of gene identification and pedigree analysis of the double mutation heterozygote of beta-thalassemia[-28(A-->G).CD17(A-->T)/N].
Methods: Polymerase chain reaction in combination with dot-blot hybridization of allele-specific oligonucleotide(PCR/ASO) probes was used.
Results: Gene identification was carried out in four probands and 35 other family members. There were 22 patients with beta-thalassemia -28(A-->G) and CD17(A-->T) mutant gene. Based on the clinical features, the results of hematological and biochemical examinations and pedigree analysis, they proved to be the double mutation heterozygote of beta-thalassemia[-28(A-->G).CD17(A-->T)/N], i.e., double point mutations on the same chromosome.
Conclusion: Double mutation heterozygote[-28(A-->G).CD17(A-->T)/N] is a new type of beta-thalassemia.