Lessons Learned from Two Missed Prenatal Cases of Hemoglobin
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tics: Cu ne rr e en G t y R r e a Wu et al., Hereditary Genetics 2015, S7 t s i e d a e r r c DOI: 10.4172/2161-1041.S7-003 e h H Hereditary Genetics ISSN: 2161-1041 Case Report Open Access Lessons Learned from Two Missed Prenatal Cases of Hemoglobin Bart’s Hydrops Fetalis Until Second Trimester Despite a Nationwide Screening Program Wu WJ1,2#, Ma GC1,3#, Wu PC4, Huang KS5, Liu YL5, Chang SP1, Ginsberg NA6 and Chen M1,2,7,8* 1Department of Genomic Medicine, and Department of Genomic Technology and Science, Changhua Christian Hospital, Changhua, Taiwan 2Department of Obstetrics and Gynecology, Changhua Christian Hospital, Changhua, Taiwan 3Institute of Biochemistry, Microbiology and Immunology, Chung-Shan Medical University, Taichung, Taiwan 4Taiji Fetal Medicine Center, Taipei, Taiwan 5Department of Obstetrics and Gynecology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan 6Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University Medical Center, Chicago, IL, USA 7Department of Obstetrics and Gynecology, College of Medicine, and Hospital, National Taiwan University, Taipei, Taiwan 8Department of Life Science, Tunghai University, Taichung, Taiwan #These authors contributed equally to this study Abstract Hemoglobin (Hb) Bart’s hydrops fetalis is the most severe form of alpha-thalassemia and has high mortality. It is caused by deletion of all four α-globin genes leading to a severe deficiency in α-globin and to the production of γ-globin tetramers, resulting in ineffective tissue oxygen delivery. Current preconceptional or prenatal screening policies for this disorder are comprehensive, but not all pregnancies with Hb Bart’s disease can be detected early before hydrops become apparent. We report here two cases with Hb Bart’s disease that escaped being detected until second trimester after hydrops fetalis occurred. These cases remind the clinicians that the importance of this well-characterized condition (alpha-thalassemia) should be reasserted despite a nationwide screening program is available. We also review the current status of prenatal screening and diagnosis of alpha-thalassemia. Keywords: Alpha-thalassemia; Hb Bart’s; Hydrops fetalis; Fetal the first or early second trimester before hydrops become apparent. ascites; Cardiomegaly Here, we report two prenatal cases of Hb Bart’s disease, which escaped being detected by current screening program until second trimester Abbreviations: Hb: Hemoglobin; SEA: Southeastern Asia; HbCS: after developing hydrops fetalis. Besides, we discuss the limitations Hb Constant Spring; HbQS: Hb Quong Sze; GA: Gestational Age; of current “comprehensive” nationwide screening program used to MCV: Mean Corpuscular Volume; CBC: Complete Blood Count; screen alpha-thalassemia, as well as to review the current status and the MCH: Mean Corpuscular Hemoglobin; MCA-PSV: Peak Systolic future prospects. Velocity of Middle Cerebral Artery; CTR: Cardiothoracic Ratio; MoM: Multiples of Median; IHUV Vmax: Intrahepatic Umbilical Venous Case Report Maximum Flow Velocity; ARMS: Amplification Refractory Mutation Patient 1 System; PCR: Polymerase Chain Reaction A 33-year-old primigravida was referred to our hospital at 20+6 Introduction weeks of gestational age (GA) after her obstetrician noted fetal ascites Alpha-thalassemia is one of the most common hereditary in routine antenatal care. The parents of the fetus were both Han hemoglobinopathies, which interferes with the production of α-globin Chinese. In the first visit to our hospital, the mother claimed that she chains of hemoglobin (Hb) and causes perinatal complications. had normal antenatal test results except iron deficiency anemia by the Approximately 5% of the world’s population carries mutant or variant result of complete cell count (CBC), ferritin, serum iron and total iron alleles over the α-globin gene, with the high frequencies throughout binding capacity. But her obstetricians didn’t request her husband to be most of Southeastern Asia (SEA), the Mediterranean area, the Indian checked. The initial ultrasound performed at our hospital showed a live subcontinent, the Middle East and Africa. In SEA region, the frequency singleton fetus whose estimated fetal weight below the 10th percentile. of α0-thalassemia variants (αα/- -) is about 5-15% [1]. Among Taiwanese, Anatomical examination demonstrated massive fetal ascites, echogenic the carrier rate of alpha-thalassemia is approximately 5-7% [2]. The bowels and cardiomegaly (cardiothoracic ratio: 0.63) (Figure 1). No disorder is associated with more than 100 known molecular defects in other structural abnormalities were noted. The amniotic fluid volume the gene cluster located on the short arm of chromosome 16 (16p13.3) and these defects can result in various clinical phenotypes [3]. Hb Bart’s hydrops fetalis is the most severe form of alpha-thalassemia, which is caused by deletion of all four α-globin genes (- -/- -), and therefore *Corresponding authors: Ming Chen, Department of Genomic Medicine, Changhua Christian Hospital, Changhua, Taiwan, Fax: 88647249847; E-mail: no α-globin is produced. As a result, γ- globin tetramers (Hb Bart’s) [email protected]; [email protected] become the dominant form of Hb and are responsible for carrying Received September 24, 2015; Accepted October 23, 2015; Published October 26, oxygen from mother to fetus. However, Hb Bart’s has a characteristic 2015 of extremely high oxygen affinity, which prevents oxygen release Citation: Wu WJ, Ma GC, Wu PC, Huang KS, Liu YL, et al. (2015) Lessons from the red blood cells to the tissue. This results in the occurrence Learned from Two Missed Prenatal Cases of Hemoglobin Bart’s Hydrops Fetalis of hydrops fetalis, stillbirth, or neonatal demise. Hence, it is critical Until Second Trimester Despite a Nationwide Screening Program. Genetics S7: 003. doi:10.4172/2161-1041.S7-003 to diagnose Hb Bart’s hydrops fetalis in early pregnancy as well as to identify high-risk groups for hereditary hemoglobinopathies. However, Copyright: © 2015 Wu WJ, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, despite the current nationwide preconceptional or prenatal screening distribution, and reproduction in any medium, provided the original author and source policies, not all pregnancies with Hb Bart’s disease can be detected in are credited. Hereditary Genetics Genetic Diseases ISSN:2161-1041 Genetics an open access journal Citation: Wu WJ, Ma GC, Wu PC, Huang KS, Liu YL, et al. (2015) Lessons Learned from Two Missed Prenatal Cases of Hemoglobin Bart’s Hydrops Fetalis Until Second Trimester Despite a Nationwide Screening Program. Genetics S7: 003. doi:10.4172/2161-1041.S7-003 Page 2 of 3 was within normal limits and peak systolic velocity of middle cerebral testing of α- and β-globin genes should be performed in addition to artery (MCA-PSV) was below 1.5 multiples of median (MoM). We electrophoresis as well as the survey for iron deficiency anemia. Below, performed amniocentesis and rechecked parental blood samples to we reviewed the current objective methods used to screening for Hb exclude the possibility of chromosome abnormality and intrauterine Bart’s hydrops fetalis, including CBC, Hb analysis and electrophoresis, infections. All of the tests were normal, but both of the parents showed genetic testing and ultrasound. Besides, we discussed the limitations of microcytic anemia (Mother: Hb: 10.6 g/dL, mean corpuscular volume each methodology (Table 1). (MCV): 69.5 fL; Father Hb: 11.6 g/dL, MCV: 69.0 fL). We highly suspected that the etiology of fetal ascites was Hb Bart’s disease. The Complete cell count DNA from the couple (from peripheral blood) and the fetus (from The commonest screening test for thalassemia is maternal CBC amniotic fluid) were thus sent for genetic testing. The results revealed that with red blood cell indices as it is easy to perform and readily available. SEA both parents are carriers of alpha-thalassemia (αα/- - ) and the fetus is a When MCV<80 fL or mean corpuscular hemoglobin (MCH)<25 case of Hb Bart’s hydrops fetalis (ζζ- -/ζζ- -). After non-directive genetic pg/cells in the absence of iron deficiency, it suggests the case would counseling and consultation of neonatal and pediatric hematological be carriers of alpha- or beta-thalassemia. Subsequent screening for specialists, the parents elected to terminate the pregnancy. husband’s red blood cell indices and further maternal Hb analysis Patient 2 are indicated to establish a diagnosis [4]. However, there is a small overlap with normal values in α+-thalassemia heterozygotes (αα/α-). A 28-year-old primigravida admitted into our hospital at GA 24+1 In addition, both iron deficiency anemia and beta-thalassemia are also weeks because of acute upper respiratory tract infection. The admission associated with mild to moderate microcytic anemia and frequently surveillance incidentally showed cardiomegaly (cardiothoracic ratio: result in incorrect diagnosis. Up to today, there is no optimal single 0.68). Reviewing her personal history, she was a victim of alpha- marker to discriminate iron deficiency anemia and thalassemia [5]. thalassemia trait. However, her husband was considered as a non- Thus, serial combined tests to exclude the possibility of iron deficiency carrier of alpha-thalassemia only by means of electrophoresis. No anemia and beta-thalassemia are required. Notably that the husband genetic testing was performed