Frequencies of HKαα and anti-HKαα Alleles in Chinese Carriers of Silent Deletional α-Thalassemia

Abstract

The HKαα (HongKongαα) allele is an unusual rearrangement of the α-globin gene cluster containing both the −α^3.7 (rightward) and ααα^{anti 4.2} crossover deletion/duplication. The anti-HKαα (anti-HongKongαα) allele is the reciprocal product containing both the −α^4.2 (leftward) and ααα^{anti 3.7} unequal crossover deletion/duplication. In clinical practice of thalassemia screening, gap-polymerase chain reaction (gap-PCR) approaches are used to detect the common −α^3.7 and −α^4.2 deletions of α-thalassemia (α-thal). Because the HKαα and anti-HKαα alleles also contain the single α-globin gene deletion, individuals with these alleles would be misdiagnosed as −α^3.7 or −α^4.2 carriers. This would likely produce misleading or incorrect information in genetic counseling. In this study, we investigated the HKαα and anti-HKαα alleles in Chinese carriers of silent deletional α-thal, and reported their frequencies to be 2.27 and 0.35% in −α^3.7 and −α^4.2 carriers, respectively. Given the rarity of the HKαα and anti-HKαα alleles, a routine screening for these two rearrangements are unlikely to be necessary on most occasions.

• α-Globin gene rearrangement
• anti-HKαα (anti-HongKongαα) allele
• Chinese
• HKαα (HongKongαα) allele
• two-round polymerase chain reaction (PCR)

Declaration of interest

This study was supported by grants from Guangzhou Health Bureau (20121A021012). The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.