Analysis of Fetal Blood: Is There Still a Role for Prenatal Diagnosis of Thalassemia?

Cord Blood Hematological Parameters of Fetuses Detected Different Thalassemia Genotypes in the Second Trimester of Pregnancy

Background

Hemoglobinopathies are the most common inherited diseases in humans resulting from impaired globin chain synthesis of hemoglobin. The progression of thalassemia rates is prevented with prenatal screening methods.

Aims

To evaluate the hematological parameters of α- and β-thalassemia and normal fetuses aged 17-25 weeks of gestation.

Study Design

A cross-sectional study.

Methods

Pregnant women who underwent cordocentesis in the second trimester because of the risk of having a baby with thalassemia were included in the study. Hematological indices and molecular DNA methods were analyzed from the cord blood samples of 129 women who were 17-25 weeks into pregnancy. The HPLC method was used for Hb fraction analysis. Amplification refractory mutation system, restriction enzyme analysis, multiplex polymerase chain reaction, and sequencing methods were used for the molecular analysis. Maternal contamination was eliminated by the short tandem repeat method.

Results

In total, 112 of the fetuses carry α- and β-thalassemia heterozygous or homozygous (α: 37, β: 58, mixed: 17) and 17 fetuses had a normal genotype for thalassemia. Significant differences in adult hemoglobin (HbA), fetal hemoglobin (HbF), Hb Barts, MCV, MCH, and RDW were detected in three groups compared with the normal group (p < 0.001, except for RBC, Hb, HCT, and MCHC). Differences in HbF, Hb Barts, MCV, MCH, and RDW were observed in the α-thalassemia groups compared with the normal group (p < 0.001). Among the five β-thalassemia subgroups, only HbA and RDW were different from the normal group (p < 0.001).

Conclusion

This study could be a good reference for future studies and prenatal diagnostic applications in emphasizing the importance of changes in the blood parameters of fetuses before molecular genotyping. These hematological data give valuable information to clinicians about the fetus to enlighten families in making appropriate decisions during prenatal diagnosis.

The Trend in Timing of Prenatal Diagnosis for Thalassemia at a Chinese Tertiary Obstetric Center

Thalassemia is a great health burden in mainland China. Carrier screening and prenatal diagnosis (PND) are essential for its prevention. The aim of this study was to describe the trend in the timing of PND for thalassemia in at-risk families in mainland China. All women who were at-risk for thalassemia and received PND at a mainland Chinese tertiary obstetric center between 2011 and 2019 were included. Information required for the survey was obtained from the database of the institute. In total, 4045 women underwent PND for thalassemia, including 1720 for β-thalassemia (β-thal) and 2325 for α-thalassemia (α-thal). The median gestational age for the PND procedure was 13 weeks. The number of PNDs performed increased year by year over this period. For both β-thal and α-thal, the proportion of women undergoing early PND also increased along with the time span. A total of 428 cases was diagnosed prenatally to be affected with β-thal major (β-TM) and 769 were affected with Hb Bart's disease. Most of the β-TM pregnancies and all of the Hb Bart's disease pregnancies were terminated. With the implementation of effective screening measures, births of affected infants have been dramatically avoided, and early PND has become the main approach, thus allowing the possibility of obtaining results at an earlier stage of pregnancy.