[Analysis of Gene Deficiency Types of Thalassemia in Lingui District of Guilin City].

Objective: To analyze the gene defect types and distribution characteristics of α- and β-thalassemia in Lingui District of Guilin City, Guangxi, so as to provide scientific basis for genetic consultation and prevention measures.

Methods: A total of 6 496 suspected cases for screening the thalassemia during physical examination, premarital examination, pregnancy examination and hospitalization in the Second Affiliated Hospital of Guilin Medical University from May 2016 to October 2019 were analyzed. Gap-PCR, PCR-RDB and DNA sequencing techniques were used to detect the types and constituent ratios of gene defects in α- and β-thalassemia positive cases.

Results: Among 6 496 suspected patients, 1 363 were thalassemia carriers, the total positive rate was 20.98%. There were 677 cases of single-gene deletion and 26 cases of double-gene detetion on the deletional α-thalassemia, 115 cases of non-deletion α-thalassemia mutation and 4 cases of deletion plus mutation. The positive rate of α-thalassemia was 12.66%. There were 11 gene abnormalities for α-thalassemia, of which --/αα (50.36%) was the most common, followed by -α/αα (23.84%); the main α-gene mutation was αα (6.93%). There were 514 β-thalassemia gene carriers, with a positive rate of 7.93%. In 12 types of β-gene mutations, CD41-42 (-TTCT) (55.64%) was the most common, followed by CD17 (A→T) (20.23%). There were 25 cases of double heterozygous α and β thalassemia (0.39%), of which -α/βCD17 (24%) and --/β41-42 (16%) were numerically dominant. Two of rare thalassemia genotypes were identified by sequencing, which were heterozygous mutations of Chinese Hong Kong type α thalassemia (HKαα/αα or HKαα/-α) and β gene mutations IVS-I (-2) or codon30 (A→G) β0, respectively.

Conclusion: Lingui district of Guilin city is a high incidence area of thalassemia. The mutation rate of α-thalassemia --/αα type deletion is relatively high, followed by that of the right deletion type (-α/αα). CD41-42 (-TTCT) has the highest mutation rate in β-thalassemia, followed by CD17(A→T). The results of this study provide reference data for the regional screening, diagnosis and treatment of thalassemia and eugenics.