Identification of Three Types of α-Thalassemia Deletion, –α21.9, –α2.4, and – –THAI, and Their Frequencies, in One Family in the Population of Southern Guangxi Zhuang Autonomous Region, People’s Republic of China

Abstract

Different types of deletional α-thalassemia (α-thal) have been reported by researchers in China. This study describes one family carrying –α21.9 (NG_000006.1: g.14373_36299delinsGGGAAGGGTGGGTGGGAATAACAGCTTTT), –α2.4 (NG_000006.1: g.36860_39251del) and – –THAI (Thailand) (NG_000006.1: g.10664_44164del) alleles in Guangxi Zhuang Autonomous Region, People’s Republic of China (PRC), and reports the frequencies of these types in the population of this region. The proband was a 4-year-old girl, who screened positive for thalassemia, although the thalassemia genotype results were normal when screened using the routine kits. Samples of the proband’s parents were also collected to perform further analyses. Two real-time gap-polymerase chain reaction (gap-PCR) systems were designed for separate detection of – –THAI and screening for –α21.9 and –α2.4. The genotype of the proband was –α21.9/–α2.4, and the two variants were inherited from her parents. In the frequency study, five – –THAI, four –α21.9 and 11 –α2.4 positive individuals were detected in the 3410 random samples. Thus, allele frequencies of –α21.9, – –THAI and –α2.4 in the population of southern Guangxi were determined as 0.059, 0.073 and 0.161%, respectively. This is the first report of an individual carrying the –α21.9/–α2.4 genotype, and the first report of the detection of –α21.9, –α2.4 and – –THAI in a single family. The total frequency for these alleles was 0.293% in southern Guangxi, suggesting that the thalassemia clinical center in this region should utilize a screening kit that allows detection of these types of deletions for a more comprehensive evaluation of thalassemia risk.