Carrier screening for alpha- and beta-thalassemia in pregnancy: the results of an 11-year prospective program in Guangzhou Maternal and Neonatal hospital

OBJECTIVES: To evaluate the first prospective screening program in China for control of alpha and beta-thalassemia in the population of pregnant couples. METHODS: During the period between January 1993 and December 2003, a hospital-based preventive program was conducted at the biggest birth center in Guangzhou, with 1/17 of all deliveries in this city referred annually by use of conventional heterozygote screening strategy in combination with the system of regular healthcare examination in pregnancy. RESULTS: The screened records included 49 221 pregnant women, and 4503 husbands of the pregnant women showed positive on the screening test. Of the at-risk couples, there were 198 for alpha-thal (4.4%) and 83 for beta-thal (1.8%), respectively. Genetic counseling was offered to all at-risk couples and a successful prenatal diagnosis was performed for 269 out of 281 (95.7%) for alpha- or beta-thal major, with the remaining 12 couples refusing to accept prenatal diagnosis. Out of 187 pregnancies at risk for homozygous alpha0-thal and 82 at risk for beta-thal major, 51 hydrops fetalis with Hb Bart's and 18 beta-thal major were identified. All pregnancies with affected fetuses were voluntarily terminated, leading to a marked reduction of severe alpha- and beta-thal births at this hospital since the program has been launched. CONCLUSIONS: Our hospital-based program proved to be highly effective in reducing severe thals in pregnant populations.     

Prenatal control of severe thalassaemia: Chiang Mai strategy

Prenatal diagnosis of severe thalassaemia is conventionally diagnosed by fetal DNA analysis but it can not be widely used due to its drawbacks of high cost and technical effort. This prospective study describes a new prenatal strategy in preventing severe thalassaemia by a more simple and inexpensive way. The strategy included: (1) genetic counselling; (2) identification of pregnancies at risk by retrospective screening (history of known risk) and prospective screening for asymptomatic women; (3) cordocentesis at 16-22 weeks' gestation; (4) fetal blood analysis with high performance liquid chromatography (HPLC); (5) termination of affected pregnancy. The prospective screening consisted of 2 min osmotic fragility (OF) and HbE screening test in women with no risk, and testing the husbands of the women with a positive result. If both of the couple had a positive result, the diagnostic test (HbA(2) level and PCR alpha-thal 1) for the carrier was needed. A pregnancy in which both of the couple were carriers was considered at risk. This strategy identified 181 and 108 couples at risk by prospective (from 7954 pregnancies) and retrospective screening, respectively. Two hundred and forty-two underwent cordocentesis, 108 from retrospective screening and 134 from prospective screening, and 62 were proven to have severe thalassaemia (29 and 33 in retrospective and prospective screening, respectively). The strategy identified nearly all, if not all, fetuses with severe thalassaemia without false positives among the screened couples. In conclusion, the strategy proves to be highly effective in the control of severe thalassaemia.     

Long-term effect of prospective detection of high genetic risk on couples' reproductive life: data for thalassaemia

Prospective risk detection with availability of prenatal diagnosis is the best service currently available for couples at high genetic risk Here we describe the long term effect of this service on the reproductive life of 102 couples at risk of thalassaemia, whose risk was detected prospectively by carrier screening, who made use of prenatal diagnosis, and where the woman is now over 40. Overall outcome for couples is described in terms of number of favourable versus unfavourable pregnancy outcomes. (A favourable pregnancy outcome = unaffected livebirth, or affected livebirth resulting from informed parental choice.) The 102 couples had a total of 356 pregnancies, including 302 viable pregnancies, and 88% achieved a family unburdened by thalassaemia. 68% of viable pregnancies had a favourable outcome, but only 43% of couples had only favourable outcomes, and 26% lost two or more viable wanted pregnancies. When early losses are included 58% of pregnancies had a favourable outcome, but only 30% of couples had only favourable outcomes, and 41% lost two or more pregnancies. Even with the best available service, at risk couples remain victims of chance, and a significant minority experience great difficulty in obtaining even one healthy child. Research is needed on approaches that may allow couples better control of reproductive outcomes.     

Cost-effectiveness of prenatal screening for thalassaemia in Hong Kong

OBJECTIVES: To determine the cost effectiveness of a universal prenatal screening program for alpha- and beta-thalassaemia. METHODS: We retrospectively reviewed our program from 1998 to 2002, and calculated the direct and indirect costs of various components. RESULTS: 18,936 women were screened at our prenatal clinic and 153 couples were subsequently referred to our Prenatal Diagnostic Centre for counselling and further investigations. In addition, there were 238 tertiary referrals and 157 self-referrals. After investigations, 84 fetuses were at risk of beta-thalassaemia major/beta-E thalassaemia, 19 of them were affected and 18 were aborted. The total expenditure on our program (HK 10.0 million dollars) would be less than the postnatal service costs (HK 40.4 million dollars) for 18beta-thalassaemia major fetuses if they were born. Of 361 women at risk of carrying a homozygous alpha0-thalassaemia fetus, 311 (86.2%) opted for the indirect approach (using serial ultrasound examinations to exclude Hb Bart's disease), and 76 (24.5%) subsequently underwent an invasive test for a definitive diagnosis. The sensitivity and false positive rate of this indirect approach was 100.0% and 2.9% respectively. CONCLUSION: It is cost effective to run a universal prenatal screening program in an area where both beta-thalassaemia and alpha-thalassaemia are prevalent. The indirect approach can effectively avoid an invasive test in unaffected pregnancies.     

Alpha-thalassaemia prenatal diagnosis by two PCR-based methods

In Cyprus all couples carrying alpha0-thalassaemia mutations are detected in the course of the thalassaemia carrier screening program and prenatal diagnosis is offered to all of them. Prenatal diagnosis for alpha-thalassaemia is routinely done by two independent molecular methods. With the first method, the mutations of the parents are directly determined by gap-PCR and then the chorionic villus sample (CVS) is examined for the presence of these mutations. With the other method, a (CA)n repeat polymorphic site located between the psialpha1- and alpha2-globin genes is used for determining the presence or absence of the normal and mutant alleles. In the period from 1995 to 1999, molecular analysis of 46 couples in which haematological data were consistent with deletion of two alpha-globin genes in both partners indicated that only 13 of them were actually at risk for haemoglobin (Hb) Bart's hydrops fetalis and prenatal diagnosis was provided in 16 pregnancies. The molecular diagnosis was possible in all cases with the use of both gap-PCR and (CA)n repeat polymorphisms analysis. No misdiagnosed cases for alpha-thalassaemia have been reported to date.     

Antenatal diagnosis of Bart's hydrops fetalis [correction of homozygous alpha thalassemia]. A case report

OBJECTIVE: Diagnosis of the Bart's hydrops fetalis [corrected]. METHOD: Bart's hydrops fetalis [corrected] was discovered by chance in the fetus of a female Chinese patient. Major intrauterine growth retardation, oligohydramnios, an immobile fetus, and cardiomegaly were the principal echographic signs. Cordocentesis showed fetal anemia, and electrophoresis of fetal hemoglobin revealed the presence of Bart's hemoglobin. RESULT: As there is no known effective treatment, termination of pregnancy was proposed to the patient. CONCLUSIONS: Bart's hydrops fetallis [corrected] is a lethal condition. Early echographic signs (cardiothoracic index >0.50, placental thickening) can be screened during weeks 17-18 or even during weeks 13-14 of gestation. These signs would permit a reduction of invasive examinations in couples at risk.     

Risk of neural tube defects in the offspring of thalassaemia carriers in Hong Kong Chinese

The risk of having an offspring with neural tube defect is negatively correlated with early pregnancy maternal folate levels. Thalassaemia carriers often have subnormal folate levels. We postulate that their offspring may be at increased risk of having neural tube defect. We retrospectively reviewed the records of 1961 Chinese women referred to a tertiary centre for prenatal diagnosis between January 1997 and August 1998. Women with a mean corpuscular volume greater than 80 fl were assumed not to be alpha-thalassaemia-1 or beta-thalassaemia heterozygotes. alpha- and beta-thalassaemia heterozygotes were diagnosed by haemoglobin studies. Of the 1961 women studied, pregnancy outcome was not available in 20 and thalassaemia screening was not available in 109 and these were excluded from the final analysis. Two-hundred-and-six women were alpha-thalassaemia-1 heterozygotes, 102 women were beta-thalassaemia heterozygotes and one woman had HbE disease. Three alpha-thalassaemia carriers and one beta-thalassaemia carrier had a pregnancy affected by anencephaly (odds=1:76). In the 1523 non-carriers, five pregnancies were affected by spina bifida (odds=1:304). The odds ratio (95 per cent confidence interval) for neural tube defects in the alpha- and beta-thalassaemia carriers was 3.99 (1.07 to 14.94; p<0.05, Chi-square test). Because of the small number of affected pregnancies studied, the finding needs to be substantiated by a larger series. If the increased risk is genuine, women need to be screened for thalassaemia before conception and the thalassaemia carriers should be given periconceptional folate supplement to reduce the occurrence of neural tube defects.     

Attitudes towards prenatal diagnosis and termination of pregnancy for thalassaemia in pregnant Pakistani women in the North of England

OBJECTIVES: Most births of children affected with beta-thalassaemia major in the United Kingdom are to parents of Pakistani origin. A popular explanation for this is that Pakistanis decline termination of pregnancy on religious grounds. However, various factors influence people's attitudes towards prenatal diagnosis and termination of pregnancy, which have not been investigated in a UK Pakistani sample. This study is aimed at exploring the attitudes of pregnant Pakistani women towards prenatal diagnosis and termination of pregnancy for beta-thalassaemia major in the North of England. METHODS: Forty-three pregnant women tested for thalassaemia carrier status were interviewed following receipt of their test results. Interviews were analysed using the grounded theory approach. RESULTS: Findings showed: (1) women's awareness of and attitudes towards prenatal diagnosis; (2) the relationship between attitudes towards prenatal diagnosis and termination of an affected foetus; (3) the relationship between attitudes towards termination of pregnancy and religious beliefs, perceptions of severity of the condition, influence of significant others, and (4) the impact of gestational age at the time of the offer of termination of pregnancy. CONCLUSIONS: Pakistani women's attitudes towards prenatal diagnosis and termination of pregnancy are influenced by various factors, and therefore their religion should not be taken as a proxy for their attitudes either for or against termination of pregnancy.     

Simplified PGD of common determinants of haemoglobin Bart’s hydrops fetalis syndrome using multiplex-microsatellite PCR

The high incidence of double-gene deletions in α-thalassaemia increases the risk of having pregnancies with homozygous α⁰-thalassaemia, the cause of the lethal haemoglobin (Hb) Bart’s hydrops fetalis syndrome. Preimplantation genetic diagnosis (PGD) has played an important role in preventing such cases. However, the current gap-PCR based PGD protocol for deletional α-thalassaemia requires specific primer design for each specific deletion. A universal PGD assay applicable to all common deletional determinants of Hb Bart’s hydrops fetalis syndrome has been developed. Microsatellite markers 16PTEL05 and 16PTEL06 within the α-globin gene cluster were co-amplified with a third microsatellite marker outside the affected region in a multiplex-PCR reaction and analysed by capillary electrophoresis. Eight informed couples at risk of having Hb Bart’s hydrops fetalis were recruited in this study and all patients underwent standard procedures associated with IVF. A total of 47 embryos were analysed. Three pregnancies were achieved from three couples, with the births of two healthy babies and one ongoing pregnancy. This work has successfully adapted an earlier protocol and developed a simple and reliable single-cell assay applicable to PGD of Hb Bart’s hydrops fetalis syndrome regardless of type of deletion.Alpha-thalassaemia is one of the most common inheritable disorders worldwide. It is a blood disorder that, in its lethal form caused by deletion of all four copies of the α-globin gene, results in the demise of the affected fetus, a condition referred to as haemoglobin (Hb) Bart’s hydrops fetalis syndrome. Preimplantation genetic diagnosis (PGD) has played an important role in preventing such cases. Current PGD protocols for deletional α-thalassaemia utilize a strategy called gap-PCR, which requires the different assays for different deletion types. We have developed a universal PGD assay applicable to all common deletional determinants of Hb Bart’s hydrops fetalis syndrome based on microsatellite marker analysis. Eight informed couples at risk of having Hb Bart’s hydrops fetalis were recruited in this study and all patients underwent standard procedures associated with IVF. Forty-five embryos were analysed in total. Three pregnancies were achieved from three couples, with the births of two healthy babies and one pregnancy still ongoing. We have successfully adapted our earlier protocol and developed a simple and reliable single cell assay applicable to PGD of Hb Bart’s hydrops fetalis syndrome regardless of the type of deletion.     

非免疫性胎儿水肿临床分析

目的:探讨非免疫性胎儿水肿的特点、临床处理及预后。方法:回顾分析2010年7月至2015年6月就诊于南京医科大学第一附属医院产科的20例胎儿水肿孕妇资料、胎儿情况及新生儿情况。结果:20例胎儿水肿均为非免疫性胎儿水肿。发现时间:妊娠14+~37+周;早孕发现2例,中孕发现4例,晚孕发现14例。有胸腔积液表现17例,腹水表现9例,皮肤水肿表现11例,羊水过多9例;脐动脉舒张期血流缺失3例,超声发现胎儿畸形4例。胎儿水肿综合征12例:7例流产、引产;其余为死胎、死产、新生儿死亡;不典型胎儿水肿8例:2例新生儿死亡,2例失访,4例预后良好。结论:部分非免疫性胎儿水肿的确切原因不明确;临床表现多样,胎儿水肿综合征预后不良,孕产妇对胎儿期望值各不相同,需针对不同情况,采取不同的监测、分娩、救治措施。     

平均红细胞体积和红细胞计数筛查妊娠合并轻型地中海贫血的价值

目的探讨平均红细胞体积(MCV)、红细胞计数(RBC)检测在筛查妊娠合并轻型地中海贫血中的价值.方法909例孕妇在常规产前检查时,同时检查外周血RBC、MCV、血红蛋白浓度、平均红细胞血红蛋白含量(MCH)、平均红细胞血红蛋白浓度(MCHC)及血红蛋白电泳等指标,根据检测结果分为地中海贫血组31例、非地中海贫血组162例、正常对照组716例.结果平均红细胞体积在正常对照组最高,非地贫组降低,地贫组最低(P＜0.01);红细胞计数在地贫组明显高于非地贫组甚至高于正常对照组(P＜0.01);RBC/MCV比值在地贫组明显高于非地贫组及正常对照组(P＜0.01),正常对照组与非地贫组之间无显著性差异.结论地中海贫血患者有明显的MCV与RBC分离现象,平均红细胞体积降低和红细胞计数升高为其特征性改变,临床上检测MCV、RBC及RBC/MCV比值有助筛查轻型地中海贫血.     

与Hb Bart’s水肿胎相关镜像综合征母体并发症的病例对照研究

目的:评价Hb Bart’s水肿胎(即α-地中海贫血1纯合子)是否并发镜像综合征和分娩孕周对母体并发症的影响。方法:回顾性分析Hb Bart’s水肿胎并发镜像综合征13例(A组)、Hb Bart’s水肿胎未并发镜像综合征61例(B组)和排除Bart’s水肿胎和血红蛋白H病(HbH)、无产科合并症的孕妇74例(C组)临床资料,对3组的实验室检查结果和母体并发症情况进行比较。另外,将74例Hb Bart’s水肿胎按照分娩孕周是否大于28周分成两个亚组,比较两亚组母体的发病情况。结果:①A组血细胞比容、血红蛋白、血小板和血清白蛋白均明显低于B、C组(P<0.05),尿酸明显高于B、C组(P<0.05);而B组和C组以上指标比较,差异均无统计学意义(P>0.05)。②A组母体严重并发症(包括弥漫性凝血功能障碍、心力衰竭、急性肺水肿、急性肾功能衰竭和HELLP综合征)、胎盘早剥、产后出血、肝肾功能损害和胎盘粘连的发生率均明显高于B组和C组(P<0.0167)。B组与C组比较,上述并发症发生率除产后出血和胎盘粘连外,其余均无统计学意义(P>0.05)。③74例Hb Bart’s水肿胎患者中,≥孕28周者,其有镜像综合征、母体有严重并发症、胎盘早剥、产后出血、肝肾功能损害和胎盘粘连的发生率均明显高于<孕28周组(P<0.05)。结论:Hb Bart’s水肿胎增加母体并发症的发生,其对母体的危害程度除了与是否并发镜像综合征有关,分娩孕周也是重要因素,临床上应重视Hb Bart’s水肿胎的早期产前诊断,一旦确诊应尽早终止妊娠,尽可能降低母体风险。     

Prenatal diagnosis of twin-twin transfusion syndrome complicated with hydrops fetalis at 14 weeks of gestation.

Twin-twin transfusion syndrome (TTTS) may complicate multiple pregnancy. Monochorionic discordant twins with oligohydramnios and polyhydramnios may be diagnostic. Hydrops fetalis is particularly ominous. All the signs can appear independently at any stage of gestation. However, TTTS with hydrops fetalis in early pregnancy is rare. We report here a case of TTTS complicated with hydrops fetalis diagnosed at 14 weeks of gestation. Our case may be one of the earliest cases of the prenatal diagnosis of TTTS complicated with hydrops fetalis in the literature.     

Invasive prenatal diagnosis of α-thalassemia to control Hb Bart’s hydrops fetalis syndrome: 15 years of experience

Purpose

The aim of the present study was to report experiences with invasive prenatal diagnosis of α-thalassemia for the prevention of Hb Bart’s hydrops fetalis syndrome in the Guangxi Zhuang Autonomous Region, China.

Methods

Pregnant women and their partners who tested positive for α⁰-thalassemia or were diagnosed with HbH diseases were counseled and suggested to undergo a prenatal diagnostic procedure for α-thalassemia. Fetal material was obtained by chorionic villus sampling (CVS) between 9 and 13 weeks of gestation, by amniocentesis between 16 and 24 weeks of gestation and by cordocentesis after 24 weeks of gestation. The α⁰-thalassemia gene types were detected by gap polymerase chain reaction (Gap-PCR). All results were finally confirmed by DNA analysis after delivery or termination of pregnancy.

Results

An invasive prenatal α-thalassemia diagnosis was performed in 3155 cases at risk for Hb Bart’s hydrops fetalis syndrome at our hospital from 2002 to 2016. CVS was performed in 1559 cases (49.4%), amniocentesis in 1240 cases (39.3%) and cordocentesis in 356 cases (11.3%). In total, 786 fetuses were diagnosed as Hb Bart’s hydrops fetalis syndrome. Among these cases, the α-thalassemia genotype was --^SEA/--^SEA in 784 cases and --^SEA/--^THAI in 2 cases. All affected pregnancies were terminated in time.

Conclusions

This extensive experience suggests that carrier screening, molecular diagnostics, genetic counselling, and prenatal diagnosis are effective measures to prevent Hb Bart’s hydrops fetalis syndrome.

     

Prenatal diagnosis of Gaucher's disease type 2. Ultrasonographic, biochemical and histological aspects

We report on the early prenatal diagnosis of fetal Gaucher disease type 2 by ultrasound examination and beta-glucosidase activity assay on amniocytes from a fetus of 15 weeks' gestation whose first sibling fetus had previously been affected with hydrops fetalis. These cases emphasize the importance of the pathological examination of all fetuses presenting with hydrops fetalis and also stress that minimal and precocious echographic signs can be suggestive of such a lysosomal storage disease.     

Mucopolysaccharidosis type VII as a cause of recurrent non-immune hydrops fetalis

BACKGROUND: Mucopolysaccharidosis type VII (MPS VII) is a rare lysosomal storage disease first described by Sly in 1973. There are fewer than thirty reported cases world wide. This extremely rare disorder can present in-utero as hydrops fetalis and has a high recurrence rate. However, prenatal diagnosis in the absence of a previously affected child, has not been reported to date. CASE: This is a case of a non-consanguineous couple, with no history of a previously affected child with MPS VII, presenting with recurrent hydrops fetalis. During the work-up, the affected fetus was diagnosed in-utero with beta-glucuronidase deficiency which is pathognomonic for MPS VII. Prenatal diagnosis was then performed in subsequent pregnancies. CONCLUSION: The importance of an extensive and thorough investigation for the etiology of hydrops fetalis is discussed.     

Prenatal control of Hb Bart’s hydrops fetalis: a two-year experience at a mainland Chinese hospital

α-Thalassemia is a common inherited disease in southern China. The severest form is Hb Bart’s hydrops fetalis, in which the affected fetuses almost always die in utero or shortly after birth, and the mothers are at high risk for severe morbidity. Therefore, this condition should be controlled, especially prenatally. In this study, we reported on a two-year experience in prenatal control of Hb Bart’s hydrops fetalis at a mainland Chinese hospital. Totally, 573 pregnancies at risk for Hb Bart’s hydrops fetalis were referred and different prenatal procedures were offered depending on the gestational age at presentation. One hundred fifty-two affected fetuses were diagnosed prenatally; among these, only half presented in early gestation, and were terminated in time. Although our prenatal program has successfully prevented the birth of children with severe thalassemia, it does not show a satisfactory outcome, considering the gestational age when an affected pregnancy is terminated.     

Selective survival of only the healthy fetus following prenatal diagnosis of thalassaemia major in binovular twin gestation

Selective feticide is the procedure of choice when, in twin binovular pregnancy, only one of the fetuses is shown to be affected. As the probabilities for this condition are almost 1:2 when the genetic disease is due to homozygosity for two autosomal recessive genes, the problem is expected to occur frequently among the ever increasing number of couples seeking prenatal diagnosis of thalassaemia and the haemoglobinopathies. The present report is the first case of this condition and the ninth in the overall medical literature.     

Womens' preference in Down syndrome screening

OBJECTIVE: To determine the knowledge of pregnant women about prenatal tests, and what tests they would choose if offered. Also, the preference of pregnant women for second-trimester or first-trimester screening was assessed. PATIENTS AND METHODS: Pregnant women receiving antenatal care in a decentralized primary care system (n=80), and pregnant women that were offered a prenatal diagnosis at the Academic Medical Centre (n=195), were asked to complete a questionnaire. RESULTS: The response rate was over 80%. Most women in both groups preferred a screening test for Down syndrome to be performed in the first trimester of pregnancy. A combination of nuchal translucency measurement and first-trimester serum screening was the option of choice. The screening possibilities for Down syndrome were less well known to the women in the low-risk group compared with the women in the high-risk group. The offer of a prenatal screening test would have been declined by more than 30% of women at low risk for carrying a fetus with Down syndrome. CONCLUSIONS: Our results show that women prefer screening for Down syndrome to be performed in the first trimester of pregnancy, using both serum and ultrasound tests. In women at low risk for Down syndrome the knowledge of prenatal screening methods was less, as well as the acceptance of prenatal screening being lower.