Supplementary Material for: Prenatal diagnosis and management of fetal anemia, caused by compound heterozygous hemoglobin Q-Thailand and hemoglobin Constant Spring

Background: Compound heterozygous hemoglobin Q-Thailand (Hb QT) and hemoglobin Constant Spring (Hb CS) are rare hemoglobinopathies found occasionally in Southeast Asia. This condition is associated with varying degrees of anemia. This report aims to describe the prenatal diagnosis, natural course, and intrauterine treatment of Hb QT/CS disease, which is thought to be more severe during fetal development than to later in life. Case: A 23-year-old pregnant woman who was at risk of fetal Hb E/-thalassemia underwent a prenatal ultrasound examination and cordocentesis at 21 weeks of gestation. The ultrasound revealed signs of fetal anemia, including mild cardiomegaly and normal peak systolic velocity in the middle cerebral artery (MCA-PSV). Fetal hemoglobin analysis revealed a diagnosis of Hb QT/CS disease which was confirmed by molecular study. A follow-up ultrasound at 23 weeks showed progressive cardiac enlargement, increased anemia, increased MCA-PSV, and mild hydropic changes. An intrauterine blood transfusion (IUT) was administered. Subsequent ultrasounds demonstrated a complete resolution of the hydropic signs. The fetus required only one IUT, and the anemia improved spontaneously later in the pregnancy. The woman delivered a healthy male newborn vaginally at 39 weeks of gestation. Conclusion: Hb QT/CS disease can lead to fetal anemia and hydrops fetalis. However, the severity of anemia in this case improves as the pregnancy progresses toward term. If the fetus survives the critical period in utero without significant organ damage from anemia, a favorable long-term prognosis is possible. This report is the first to describe the prenatal diagnosis, natural course, and intrauterine treatment of Hb QT/CS disease with a successful outcome.