Comparison of the Performances of Middle Cerebral Artery Peak Systolic Velocity and Cardiothoracic Diameter Ratio in Predicting Fetal Anemia: Using Fetal Hemoglobin Bart’s Disease as a Study Model

<b><i>Objective:</i></b> The aim of the study was to compare the performances of cardiothoracic diameter ratio (CTR) and middle cerebral artery peak systolic velocity (MCA-PSV) in predicting fetal hemoglobin (Hb) Bart’s disease and identify the best CTR cut-off for each gestational period. <b><i>Methods:</i></b> Pregnancies at risk of fetal Hb Bart’s disease (gestational ages of 12–36 weeks) were prospectively recruited to undergo ultrasound examination. The measurements of CTR and MCA-PSV were performed and recorded before invasive diagnosis. <b><i>Results:</i></b> During the study period (2005–2019), a total of 1,717 pregnancies at risk of fetal Hb Bart’s disease met the inclusion criteria and were available for analysis, including 329 (19.2%) fetuses with Hb Bart’s disease. The mean gestational age at the time of diagnosis was 19.30 ± 5.6 weeks, ranging from 12 to 36 weeks. The overall performance of CTR <i>Z</i>-scores is superior to that of MCA-PSV multiple of median (MoM) values; area under curve of 0.866 versus 0.711, <i>p</i> value &#x3c;0.001. The diagnostic indices of CTR and MCA-PSV are increased with gestational age. Based on receiver operating characteristic curves of CTR <i>Z</i>-scores, the best cut-off points of CTR at 12–14, 15–17, 18–20, 21–23, and ≥24 weeks are 0.48, 0.49, 0.50, 0.51, and 0.54, respectively. The best cut-off of MCA-PSV is 1.3 MoM, giving the best performance at 21–23 weeks with a sensitivity of 91.8% and specificity of 85.5%. <b><i>Conclusion:</i></b> The performance of CTR is much better than MCA-PSV in predicting fetal anemia caused by Hb Bart’s disease. Nevertheless, whether this can be reproduced in anemia due to other causes, like isoimmunization, is yet to be explored.

Fetal Hemodynamic Response to Anemia in Early Gestation: Using Hemoglobin Bart’s Disease as a Study Model

Objective To assess fetal hemodynamic changes in response to anemia in early gestation, using fetal Hb Bart’s disease as a study model. Methods A prospective study was conducted on pregnancies at risk for fetal Hb Bart’s disease at 12–14 weeks of gestation. Fetal hemodynamics were comprehensively assessed by 2D ultrasound, Doppler velocity, and cardio-STIC just prior to the invasive procedure for diagnosis. The various hemodynamic parameters of the affected and unaffected fetuses were compared. Results Of 56 fetuses at risk, 17 had Hb Bart’s disease and 39 were unaffected. The right and combined ventricular cardiac outputs (CO) were significantly higher in the affected fetuses (0.993 vs. 1.358; p < 0.001 and 1.010 vs. 1.236; p < 0.001, respectively), whereas the left CO tended to be higher but not significantly (1.027 vs. 1.113; p = 0.058). Cardiac dimensions, middle-cerebral artery peak systolic velocity, Tei index, and isovolemic contraction time were significantly increased, while the global sphericity index was significantly decreased. Interestingly, cardiac preload, ventricular wall thickness, shortening fraction, isovolemic relaxation time, and fetal heart rate were unchanged. Four fetuses had hydropic changes, but all cardiac functions were normal. Conclusion Fetal anemia induces hypervolemia and increases cardiac output to meet the tissue oxygen requirement, resulting in an increase in size without hypertrophy, volume load without pressure load, and a decrease in the globular sphericity index. The heart works very well but works harder, especially systolic ventricular load. Hydrops fetalis due to anemia appears not to be caused by heart failure as previously believed but rather by volume load with high vascular permeability at least in early pregnancy.

Performance of Fetal Cardiac Volume Derived from VOCAL (Virtual Organ Computer-Aided AnaLysis) in Predicting Hemoglobin (Hb) Bart’s Disease

Objective: To determine the performance of fetal cardiac volume (CV) in the detection of fetal Hb Bart’s disease among fetuses at risk at 18–22 weeks of gestation and to compare the performance with those of cardiothoracic diameter ratio (CTR) and middle cerebral artery peak systolic velocity (MCA-PSV). Methods: Fetuses at risk of Hb Bart’s disease between 18 and 22 weeks of gestation prospectively underwent echocardiography with acquisition of the volume datasets (VDS) of fetal heart, using 4D-cardiac STIC. Subsequently, off-line analysis was blindly performed to measure cardiac volume using the VOCAL technique. Results: A total of 502 fetuses at risk meeting the inclusion criteria were included in the analysis, consisting of 117 (23.3%) fetuses with Hb Bart’s disease and 385 (76.7%) unaffected fetuses. The mean (±SD) gestational age at the time of ultrasound examination was 19.70 ± 1.3 weeks. In predicting fetal Hb Bart’s disease, CV, using a cut-off Z-score of 1.7, had a sensitivity of 94.9% and specificity of 94.0%. The performance of CV was slightly better than that of CTR but very superior to that of MCA-PSV (areas under curve: 0.988, 0.974 and 0.862, respectively). Conclusions: Fetal CV has a very high performance in predicting fetal Hb Bart’s disease at mid-pregnancy, comparable with CTR and much better than MCA-PSV.

Severe fetal anemia and hydrops fetalis associated with compound heterozygosity for Hb Zurich-Albisrieden (HBA2:c.178G>C) and Hb Quong Sze (HBA2:c.377T>C)

We report on a fetus with cardiomegaly and increased middle cerebral artery-peak systolic velocity at 25 weeks of gestation. Severe fetal anemia (hemoglobin (Hb) level 37 g/L) was confirmed by cordocentesis. Hb analysis showed that Hb Bart’s was 9% in cord blood. Molecular analysis of the proband’s family found that the mother was a carrier of Hb Quong Sze (Hb QS, HBA2:c.377T>C), the father was a carrier of Hb Zurich-Albisrieden (Hb ZA, HBA2:c.178G>C), and the fetus was a compound heterozygote for Hb ZA and Hb QA. Despite intrauterine blood transfusions, the fetus experienced problems including oligohydramnios, growth retardation, placental thickening, and heart enlargement in the third trimester. The couple chose to terminate the pregnancy, and fetal autopsy confirmed the above diagnosis. This is the first report of a case of Hb ZA compounded with Hb QS, and provides a reference for genetic counselling and prenatal diagnosis in the Chinese population.

Oxidative Stress and Inflammatory Markers of Cordocentesis Blood in Response to Fetal Anemia

Background: Hypothetically, fetal anemic hypoxia causes cellular damage with an increase in oxidative stress levels. This study, using hemoglobin (Hb) Bart’s disease as a study model, aims to compare the levels of oxidative stress and inflammatory markers as well as fetal hemodynamics in anemic fetuses with those of non-anemic fetuses. Materials and Methods: Forty pregnancies at risk of fetal Hb Bart’s disease scheduled for cordocentesis at 18 to 22 weeks were recruited into the study. Fetal blood was collected to measure the levels of 8-Isoprostane (8-Isop), tumor necrosis factor-alpha (TNF-α), interleukin-10 (IL-10), and hemoglobin as well as for hemoglobin typing. Results: There was no significant difference in cord blood 8-Isop, TNF-α, and IL-10 levels between the Hb Bart’s disease group and the unaffected group, whereas several hemodynamic parameters, such as cardiac output, cardiac size, cardiac performance, middle cerebral artery – peak systolic velocity, etc., were significantly changed in the fetal Hb Bart’s group. In the subgroup analysis, the level of serum 8-Isop in the severe anemia group tended to increase, though not significantly, compared with the non-anemic group (275.3±141.8 vs 203.9±49.2 pg/mL; p=0.079). Conclusions: In response to anemia, fetuses might have a high capacity of hemodynamic adaptation without significant cellular damage, though a trend of an increase in oxidative stress marker was found in severe fetal anemia. Theoretically, intrauterine blood transfusion for fetal anemia during adaptive compensation may result in no residual insults.

Characterisation of two unusual cases of haemoglobin Bart’s hydrops foetalis caused by –SEA and large novel α-globin gene cluster deletions

Background We describe 2 unusual haemoglobin (Hb) Bart’s hydrops cases that could not be explained by traditional factors. Case presentation: Two families with a diagnosis or history of foetal hydrops were enrolled. A suspension-array system was used to detect the 23 most frequent mutations in southern China. Multiplex ligation-dependent probe amplification (MLPA) was used to screen for possible deletions. Precise characterisation of the breakpoints of the novel variants and uniparental disomy analysis were performed using a single nucleotide polymorphism (SNP) array. Quantitative fluorescence PCR was used to eliminate maternal cell contamination and nonpaternity. In case 1, the suspension-array system indicated a maternal heterozygous (–SEA/) deletion, and the paternal sample was negative. The foetal hydrops was caused by the maternal (–SEA/) deletion and a de novo α-globin gene deletion (–193). In case 2, the paternal sample had a heterozygous (–SEA/) deletion, and MLPA and SNP array analysis revealed a large maternal deletion (–227) that encompassed the α-globin gene, which explained the history of Hb Bart’s foetal hydrops. Conclusions Our cases describe 2 new α0-thalassaemia deletions and illustrate the importance of using a combination of methods to detect rare types of α-thalassaemia.

Phát hiện đột biến mất đoạn hai gen Alpha Globin (--SEA) gây bệnh Αlpha Thalassemia bằng kỹ thuật PCR

Đặt vấn đề: Chẩn đoán xác định người mang đột biến dị hợp tử --SEA có ý nghĩa lớn với việc chẩn đoán trước sinh. Chẩn đoán sớm thai bị Hb Bart’s có vai trò quan trọng cho tư vấn di truyền. Mục tiêu: Đánh giá hiệu quả của việc phát hiện đột biến --SEA bằng phương pháp PCR. Đối tượng và phương pháp nghiên cứu: 66 mẫu DNA tách chiết từ 31 mẫu máu và 35 mẫu ối tươi/ối nuôi cấy đã làm xét nghiệm đột biến gen α globin bằng phương pháp lai phân tử ngược tại Trung tâm Tư vấn Di truyền, Bệnh viện Đại học Y Hà Nội. Các mẫu DNA được PCR bằng mồi đã thiết kế, sau đó điện di để xác định đột biến --SEA. So sánh kết quả giữa hai phương pháp. Kết quả: Đoạn mồi thiết kế đã khuếch đại thành công đoạn gen mang đột biến --SEA. 66/66 mẫu máu và mẫu ối có kết quả 100% tương đồng giữa hai phương pháp. Kết luận: PCR là một phương pháp chính xác, đơn giản, nhanh chóng và kinh tế trong chẩn đoán người mang gen cũng như chẩn đoán thai thi mang đột biến --SEA.

Fetal Cardiac Cellular Damage Caused by Anemia in Utero in Hb Bart’s Disease

Background: Severe fetal anemias can cause high output cardiac failure. Mitochondria are key regulators of cardiac function. However, the effects of an early phase of fetal anemia on the fetal heart and cardiac mitochondrial function are not known. Objective: To compare mitochondrial function and cardiac biochemical alterations in the fetal cardiac tissue between anemic and nonanemic fetuses. Methods: A cross-sectional study was conducted in Fetuses affected by Hb Bart’s disease (n=18) and non-anemic fetuses (n=10) at 17-20 weeks. Echocardiograms had been carried out in all cases to assess prenatal cardiac function. Cardiac tissues were collected after pregnancy termination for determination of cardiac iron accumulation, mitochondrial function including mitochondrial ROS production, mitochondrial depolarization and mitochondrial swelling, mitochondrial dynamics, inflammation, and apoptosis. Results: Prenatal cardiac function evaluated by ultrasound was comparable between the Hb Bart’s and non-anemic groups. In the Bart’s group, the levels of cardiac mitochondrial depolarization and swelling, and the TNF-α level were significantly higher, compared to the nonanemic group. To the contrary, anti-inflammatory (IL-10) levels were significantly lower in the Hb Bart’s group. Additionally, active caspase3 and Bcl-2 expression were also significantly higher (P= 0.001, P=0.035) in the Bart’s group. The mitochondrial fission protein expression including p-DRP1/total DRP1 was significantly higher in the Bart’s group. However, there was no difference in cardiac iron accumulation levels between these two groups. Conclusion: Despite equivalent prenatal cardiac function and comparable cardiac iron accumulation in the Bart’s and non-anemic groups, fetal anemia is significantly associated with cardiac mitochondrial dysfunction, increased mitochondrial fission, and increased inflammation and apoptosis. These findings indicate that an early phase of fetal anemia without cardiac iron overload can lead to cardiac mitochondrial dysfunction in fetuses with Hb Bart’s.