OBJECTIVE: To determine the frequency of Hong Kong αα (HK αα) gene in α3.7 positive samples among carriers from Fujian area. METHODS: Routine genetic testing for thalassemia was carried out for 10145 patients with positive screening results. Single PCR and two-round nested PCR were utilized to detect HK αα among 507 patients with α3.7/αα and 2 patients for whom electrophoresis showed α3.7, -αSEA and normal α2 alleles. Reverse dot blot test was used for detecting non-deletional α-thalassemia and β-thalassemia variants. RESULTS: Among the 507 patients with α3.7/αα, HK αα was identified in 35 cases, which included 25 HK αα/αα, 5 HK αα/α3.7, 4 HK αα/αα with heterozygous CD41/42 (HBB: c.126_129delCTTT) variant, 1 HK αα/αα with IVS-II-654 (HBB: c.316_197C>T) heterozygous variant. One patient was confirmed to have α3.7/anti4.2 genotype. The two cases with α3.7, -αSEA and normal α2 alleles were confirmed to be HK αα/--SEA. The frequency of HK αα genotype in Fujian area was therefore 7.27% among patients with α3.7 and 0.36% in the general population. CONCLUSION A certain proportion of HK αα has been detected in Fujian area, which will enable more accurate diagnosis and genetic counseling.
Genotype ; Heterozygote ; Hong Kong ; Humans ; alpha-Thalassemia ; beta-Thalassemia