IthaID: 3432

Also known as:

Comments: The HKαα allele results from a complex rearrangement of the α-globin gene cluster containing both the -α3.7 [IthaID: 300] and ααα(anti 4.2) [IthaID: 2569] unequal crossover junctions on the same chromosome. The HKαα allele contains neither a single gene deletion nor triplication. It consists of two functional genes; α2 and α2/α1 (fusion) genes (See [PMID: 22989259] for a diagram illustrating the crossover that leads to the HKαα allele). Heterozygotes with the HKαα allele (HKαα/αα and βN/βN) present with normal hematological phenotype. The α-globin mRNA level of the HKαα allele heterozygotes (HKαα/αα) is similar to that of normal individuals (αα/αα). Individuals with HKαα/-α4.2 or HKαα/αWSα genotypes showed silent α-thalassemia, while individuals with the HKαα/--SEA genotype showed mild α-thalassemia. HKαα/αα and HKαα/-α3.7 combined with the HBB variant displayed obvious hematological features of β-thalassemia [PMID: 36388814]. The HKαα allele can be detected and distinguished from other co-inherited α alleles using TGS based on single-molecule real-time (SMRT) technology.

We follow the HGVS sequence variant nomenclature and IUPAC standards.

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Heterozygous records (preview in IthaPhen)

1. Li Z, Cai S, Rong K, Song G, Li Y, Guo R, The first compound heterozygosity for HKalpha alpha allele and Southeast Asian deletion allele., Clin. Biochem., 40(0), 407-10, 2007 PubMed
2. Shang X, Li Q, Cai R, Huang J, Wei X, Xu X, Molecular characterization and clinical presentation of HKαα and anti-HKαα alleles in southern Chinese subjects., Clin. Genet., 83(5), 472-6, 2013 PubMed
3. Wu MY, Li J, Li SC, Li R, Liao C, Li DZ, Compound Heterozygosity for HKαα and an in Cis Deletion of Double α Genes Presents as α-Thalassemia Trait., Hemoglobin, 39(4), 256-9, 2015 PubMed
4. Zhang M, Huang H, Chen M, Chen L, Wang Y, Lin N, Li Y, Chen X, Wang L, Lin Y, Xu L, [Variant analysis for patients from Fujian area with Hong Kong αα type thalassemia]., Zhonghua Yi Xue Yi Chuan Xue Za Zhi, 36(4), 297-300, 2019 PubMed
5. Li J, Ye G, Zeng D, Tian B, Wang W, Feng Q, Zhu C, Accurate genotype diagnosis of Hong Kongαα thalassemia based on third-generation sequencing., Ann Transl Med, 10(20), 1113, 2022 PubMed