[Molecular Epidemiological Characteristics and Differential Diagnosis of Common δβ-Thalassemia/HPFH]

To investigate the molecular epidemiological characteristics of common δβ-thalassemia/hereditary persistence of fetal hemoglobin(HPFH) in the prepregnant population in Huadu, and to provide a laboratory basis for prevention and control of thalassemia.

Blood samples of childbearing age people in Huadu District of Guangzhou who participated in free thalassemia testing from January 2016 to July 2021 were collected for hematological parameters analysis and hemoglobin electrophoresis. Chinese ^Gγ⁺(^Aγδβ)⁰-thalassemia, ^SEA-HPFH and Taiwanese deletion β-thalassemia were detected by Gap-PCR in the samples with higher HbF(≥5%). Primers were designed for the proximal HBG1 and HBG2 promoter, and the point mutations in the proximal promoter region were detected by Sanger sequencing. Hematology parameters data were statistically analyzed.

Among 27 088 samples, Thirteen cases of Chinese ^Gγ⁺(^Aγδβ)⁰-thalassemia and thirty-three cases of ^SEA-HPFH were detected, which including 3 cases of Chinese ^Gγ⁺(^Aγδβ)⁰/β^N compounded with --^SEA/αα and three cases of ^SEA-HPFH/β^N compounded with --^SEA/αα. 6 carriers with ^Aγ-196 C>T were also detected; No Taiwanese thalassemia genetype was detected. The total detection rate of common δβ-thalassemia/HPFH was 0.19% (52/27 088). There were significant differences in the levels of MCV, MCH, HbA₂, and HbF among Chinese ^Gγ⁺(^Aγδβ)⁰-thalassemia, ^SEA-HPFH, ^Aγ-196 C>T (P<0.001). The hematological parameters of ^Aγ-196C>T combined with α⁰-thalassemia were similar to those of Chinese ^Gγ⁺(^Aγδβ)⁰-thalassemia carriers, and only HbA₂ was significantly lower than that of the latter, which was helpful for clinical identification.

δβ-thalassemia/HPFH should be included in the scope of thalassemia prevention program in the prepregnant population in Huadu District, and hematological parameters can provide some basis for identifying different types of δβ-thalassemia/HPFH.