To explore the genotypes and hematological characteristics of patients with αβ-thalassemia in the northern of Guangzhou.

Outpatients, inpatients, and physical examination patients who underwent genetic testing of thalassemia (n=14 600) in the Huadu District Maternal and Child Healthcare Hospital in Guangzhou from January 2018 to December 2019 were enrolled. The patients were screened by blood routine test and hemoglobin electrophoresis analysis, α-thalassemia and β-thalassemia genotypes were detected by Gap-PCR and flow-through hybridization technology among the positive samples by the primany screening, and genetic sequencing methods were used for rare genotypes. Statistical analysis was carried out on the hematological indicators of αβ-thalassemia group whose clinical manifestations were β-thalassemia (n=250) and pure β-thalassemia group (n=250) who were selected randomly.

Two hundred and fifty-four cases of αβ-thalassemia were detected in 14 600 subjects with a population incidence of 1.74% (254/14 600). A total of 41 genotypes were detected, the most prevalent genotype was --^SEA/αα and β^IVS-Ⅱ-654/β^N(40 cases), the next was --^SEA/αα and β^CD41-42/β^N(32 cases), and -α^3.7/αα and β^CD41-42/β^N(25 cases) ranked third. Among 254 cases of αβ-thalassemia group, there were 250 cases with clinical manifestations of β-thalassemia. Red blood cells (RBC) [(5.62±0.74)×10¹²/L], mean corpuscular volume (MCV)[(67.64±5.52)fl], mean corpuscular hemoglobin (MCH) [(21.68±1.73)pg] in αβ-thalassemia group (n=250) were compared with those in pure β-thalassemia group (n=250) [(6.10±0.85)×10¹²/L, (63.61±5.01) fl, (20.49±1.89)pg], the differences were statistically significant (t=4.86, -6.14, -5.24, all P<0.01). Hemoglobin (HGB) [(121.52±14.67)g/L] and hemoglobin A₂ (HbA₂) [(5.23±0.51)%] in αβ-thalassemia were compared with pure β-thalassemia group [(124.42±15.20)g/L, (5.29±0.55)%], there were no significant differences (t=1.55, 0.79, all P>0.05).

The αβ-thalassemia genotype in northern of Guangzhou is complex and diverse, with high incidence rate, high genetic heterogeneity and diversity, and lacks specific hematological indicators for diagnosis. When hematological phenotype and genotype are inconsistent, rare genotypes should be considered, αβ-thalassemia genotype diagnosis must be rely on molecular diagnosis methods.