Prenatal Diagnosis Of Thalassemia Research Articles

In response to "Role of Fetal Blood Sampling in the Prenatal Diagnosis of Thalassemia".

In response to "Role of Fetal Blood Sampling in the Prenatal Diagnosis of Thalassemia".

Role of Fetal Blood Sampling in the Prenatal Diagnosis of Thalassemia.

Role of Fetal Blood Sampling in the Prenatal Diagnosis of Thalassemia.

Molecular characterization of a novel 83.9-kb deletion of the α-globin upstream regulatory elements by long-read sequencing

Inherited deletions of upstream regulatory elements of α-globin genes give rise to α-thalassemia, which is an autosomal recessive monogenic disease. However, conventional thalassemia target diagnosis often fails to identify these rare deletions. Here we reported a family with two previous pregnancies of Hb Bart's hydrops fetalis and was seeking for prenatal diagnosis during the third pregnancy. Both parents had low level of Hemoglobin A2 indicating α-thalassemia. Conventional Gap-PCR and PCR-reverse dot blot showed the father carried –SEA deletion but did not identify any variants in the mother. Multiplex ligation-dependent probe amplification identified a deletion containing two HS-40 probes but could not determine the exact region. Finally, a long-read sequencing (LRS)-based approach directly identified that the exact deletion region was chr16: 48,642-132,584, which was located in the α-globin upstream regulatory elements and named (αα)JM after the Jiangmen city. Gap-PCR and Sanger sequencing confirmed the breakpoint. Both the mother and fetus from the third pregnancy carried heterozygous (αα)JM, and the fetus was normally delivered at gestational age of 39 weeks. This study demonstrated that LRS technology had great advantages over conventional target diagnosis methods for identifying rare thalassemia variants and assisted better carrier screening and prenatal diagnosis of thalassemia.

An analysis of the distribution and spectrum of alpha thalassemia mutations in Rasht City, North of Iran.

Alpha thalassemia is one of the most common hereditary hemoglobin disorders worldwide, particularly in the Middle East, including Iran. Therefore, determining the spectrum and distribution of alpha thalassemia mutation is a fundamental component of preventive approaches and management strategies. The present study reviews the genetic testing and blood laboratory results of 455 candidates eligible for marriage who were suspected of being thalassemia carriers and on whom genetic testing was performed from 21 March 2013 to 31 December 2020 in Rasht City. A total of 114 (25.05%) alpha thalassemia cases were identified. Fifteen different alpha mutations were found. The most common mutation among the study population was -α3.7 deletion in 55 patients (48.24%), followed by Hb Constant Spring (C.S) in 21 patients (18.42%) and poly A2 in 16 (14.03%). Also, most of the patients were silent carriers. The deletion type of mutation was much more common than non-deletion mutations. Our study reveals genetic heterogeneity and alpha thalassemia diversity among the Rasht City population. We expect that these findings will help guide premarital screening and genetic counseling, prenatal diagnosis of thalassemia, preventive strategy development, as well as a compilation of the alpha thalassemia catalog in Guilan province.

Evaluating the Clinical Utility of a Long-Read Sequencing-Based Approach in Prenatal Diagnosis of Thalassemia.

The aim is to evaluate the clinical utility of a long-read sequencing-based approach termed comprehensive analysis of thalassemia alleles (CATSA) in prenatal diagnosis of thalassemia. A total of 278 fetuses from at-risk pregnancies identified in thalassemia carrier screening by PCR-based methods were recruited from 9 hospitals, and PCR-based methods were employed for prenatal diagnosis. CATSA was performed retrospectively and blindly for all 278 fetuses. Among the 278 fetuses, 263 (94.6%) had concordant results and 15 (5.4%) had discordant results between the 2 methods. Of the 15 fetuses, 4 had discordant thalassemia variants within the PCR detection range and 11 had additional variants identified by CATSA. Independent PCR and Sanger sequencing confirmed the CATSA results. In total, CATSA and PCR-based methods correctly detected 206 and 191 fetuses with variants, respectively. Thus, CATSA yielded a 7.9% (15 of 191) increment as compared with PCR-based methods. CATSA also corrected the predicted phenotype in 8 fetuses. Specifically, a PCR-based method showed one fetus had homozygous HBB c.52A > T variants, while CATSA determined the variant was heterozygous, which corrected the predicted phenotype from β-thalassemia major to trait, potentially impacting the pregnancy outcome. CATSA additionally identified α-globin triplicates in 2 fetuses with the heterozygous HBB c.316-197C > T variant, which corrected the predicted phenotype from β-thalassemia trait to intermedia and changed the disease prognosis. CATSA represents a more comprehensive and accurate approach that potentially enables more informed genetic counseling and improved clinical outcomes compared to PCR-based methods.

Molecular Spectrum, Ethnic and Geographical Distribution of Thalassemia in the Southern Area of Hainan, China.

BackgroundThalassemia is one of the most common genetic diseases in southern China. Accurate population frequency data regarding the occurrence and distribution of thalassemia are important for designing appropriate prevention strategies for thalassemia. This study aims to reveal the molecular spectrum, ethnic and geographical distribution of thalassemia in the southern area of Hainan Province, China.MethodsA total of 9813 suspected carriers of thalassemia were screened for genetic analysis by using the PCR-reverse dot blot hybridization method targeting three known deletions of α-thalassemias (--SEA, -α3.7, and -α4.2), three nondeletional mutations of α-thalassaemias (αCS, αQS, and αWS) and the 17 most common mutations of β-thalassaemias in the Chinese population.ResultsApproximately 6,924 subjects were genetically diagnosed as thalassemia carriers or patients, including 5812 cases of α-thalassemia (83.9%), 369 cases of β-thalassemia (5.3%), and 743 cases of α-composite β-thalassemia (10.7%). A total of 21 distinct genotypes were identified among the 5,812 α-thalassemia carriers, -α4.2/αα, -α3.7/αα, and -α3.7/-α4.2 were the most common α-thalassemia genotypes. The most frequent β-thalassemia genotype was βCD41−42/βN, with a notable proportion of 69.6%, followed by the β−28M/βN, βIVS−II−654/βN, βCD71−72/βN, βE/βN, and βCD17/βN genotypes. In addition, 37 genotypes were detected among the 743 cases of both α- and β-thalassemia mutations. The α-thalassemia genotypes were most commonly found in the Li people, who accounted for 73.5% of α-thalassemia carriers. The β-thalassemia genotypes were most commonly identified in the Han people, who accounted for 59.4% of β-thalassemia carriers. Among the subjects carrying both α- and β-thalassemia variations, only three ethnic minorities were identified, including the Li, Han, and Miao people, accounting for 82.0, 17.4, and 0.7%, respectively.ConclusionsOur study indicates that there is high genetic heterogeneity, geographical and ethnic differences in thalassemia in populations in the southern area of Hainan Province. These findings will be helpful in guiding genetic counseling and prenatal diagnosis of thalassemia in Hainan Province.

Five Variable Number of Tandem Repeats Loci (D17S5, APOB, TPO Intron 10, IL-1α Intron 6, and CIAS1) in Thais and Application in the Prenatal Diagnostic Laboratory.

Background: Prenatal diagnosis of genetic disease requires DNA analysis of fetal tissue of a responsible gene. Accurate diagnosis is useful for the appropriate management of pregnancy. However, maternal contamination of fetal specimens poses a high preanalytical risk of prenatal misdiagnosis. We have examined five variable number of tandem repeat (VNTR) polymorphisms for use in monitoring potential maternal contamination. Materials and Methods: A study was conducted to examine the heterozygosities of five VNTR loci including, D17S5, APOB, TPO intron 10, IL-1α intron 6, and CIAS1 in 200 unrelated Thai subjects and applied to the monitoring of maternal contamination in 22 families at risk of having fetuses with severe thalassemia. Results: The heterozygosities of D17S5, APOB, TPO intron 10, IL-1α intron 6, and CIAS1 VNTRs were 59.5, 19.5, 66.0, 35.5, and 42.0%, respectively. Therefore, the TPO intron 10 and D17S5 loci were chosen for prenatal diagnosis of thalassemia in 22 families. Analyses of these VNTRs demonstrated an increase of informative data from 59.1% provided by the routine D1S80 VNTR analysis to 90.9%. Conclusions: The VNTR diagnostic procedure described above is simple, cost-effective, rapid, and does not require the use of sophisticated instruments; it should prove useful in the prenatal diagnosis of thalassemia.

Genetic Analysis and Prenatal Diagnosis of Thalassemia in Couples of Childbearing Age in Quanzhou Region Fujian Province, China

To explore the genotypes and prenatal diagnosis of thalassemia in couples of childbearing age in Quanzhou, Fujian Province. Blood routine and hemoglobin electrophoresis were performed for initial thalassemia screening in 76 328 couples in Quanzhou region from July 2017 to July 2020. The couples with positive initial screening results further underwent thalassemia gene test. Couples carrying homotypic thalassemia genes underwent prenatal diagnosis in the second trimester. Among 76 328 couples of childbearing age, 1 809 couples of positive initial thalassemia screening were identified, with the positive rate about 2.37%. Further results of genetic detection of the 1 809 couples showed that 985 cases were diagnosed as α- thalassemia, of which --sea/αα was the most frequency, followed by -α3.7/αα and ααQS/αα; 296 cases were diagnosed as β-thalassemia, the most frequency mutations were 654M/N and 41-42M/N; 26 cases of compound α and β-thalassemia were detected. In addition, 3 rare cases of thalassemia were detected, including --THAI/αα, SEA-HPFH, and -α6.9/--sea. Among them, 108 couples were confirmed as homologous thalassemia, with the detection rate about 5.97%, including 96 couples of homologous α-thalassemia, 9 couples of homologous β-thalassemia, and 3 couples with one had compound α- and β-thalassemia. Among them, 17 couples with homologous α-thalassemia underwent prenatal diagnosis in the second trimester, of which 1 case of Hb Bart's Hydrops Syndrome, 3 cases of HbH disease, 9 cases of silent thalassemia or α-thalassemia minor, and 4 cases of healthy fetuses were detected. Fetal chromosome karyotype analysis showed that 16 cases were normal and 1 case diagnosed as Down syndrome. Thalassemia screening in pre-marital and pre-pregnancy, and prenatal diagnosis can effectively reduce the birth of children with thalassemia intermediate and thalassemia major. It is necessary to perform chromosome karyotype analysis at the same time as prenatal diagnosis of thalassemia gene in order to avoid fetus with abnormal chromosome.

Prenatal diagnosis of thalassemia: A cost-effective step towards eradication

Prenatal diagnosis of thalassemia: A cost-effective step towards eradication

Prenatal diagnosis of thalassemia in 695 pedigrees from southeastern China: a 10-year follow-up study.

Thalassaemia is highly prevalent in southeastern China. This 10-year follow-up study aimed to characterize the genotype and karyotype of thalassaemia in fetal samples derived from thalassemia carriers in Fujian province, southeastern China. A total of 476 prenatal samples from 472 couples carrying α-thalassaemia traits and 224samples from 223 couples carrying β-thalassaemia traits were collected for STR analysis, detection of thalassemia genotypes and karyotyping. The common deletional α-thalassemias and rare thalassemia genotypes were detected using Gap-PCR assay, and the common β-globin gene mutations were detected using PCR-RDB assay. We detected 43.49% prevalence of α-thalassaemia minor, 26.05% prevalence of α-thalassaemia intermediate and major and 1.89% prevalence of rare form among the 476 prenatal samples from couples with α-thalassaemia, and 85 fetuses with β-thalassemia heterozygote, 16 with homozygote and 21 with double heterozygote, and a rare βIVS-2-654(C→T) /Chinese Gγ (A γδβ)0 genotype among the 224 prenatal samples from couples with β-thalassemia. Karyotyping showed 7 fetuses with abnormal karyotypes. Totally 153 pregnancies were terminated, and genetic diagnosis of thalassemia using fetal umbilical cord blood following induction of labor showed consistent results with prenatal diagnosis. No thalassemia phenotypes were identified in normal infants half a year after birth, and the infants with α-thalassemia and β-thalassemia minor had no or mild anemia symptoms, but normal development, while 15 babies with hemoglobin H disease presented moderate anemia symptoms. Our data suggest the pregestational screening of thalassemia, notably compound and rare forms of thalassemia, for couples carrying thalassemia traits.

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.

Non‑invasive prenatal diagnosis of thalassemia through multiplex PCR, target capture and next‑generation sequencing

Prenatal clinical detection of thalassemia involves gap-PCR and reverse dot blot (RDB) analysis of fetal DNA acquired through invasive methods. The present study aimed to develop a non-invasive prenatal diagnostic method for thalassemia based on next-generation sequencing (NGS). A total of eight families with proband children with thalassemia were recruited for the study during a subsequent pregnancy. The sequence of the thalassemia genes of the parents and proband were determined using NGS, based on a thalassemia AmpliSeq panel. Cell-free plasma DNA from pregnant women related to the aforementioned proband was analyzed using an NGS panel, based on thalassemia-associated capture probes. Heterozygous single nucleotide polymorphisms within the 10 kb regions flanking exons of the targeted thalassemia genes were acquired using probes or AmpliSeq and employed for parental haplotype construction using Trio-based panel sequencing. The fetal haplotype was deduced from the parental haplotypes and relative haplotype dosage, and subsequently validated using gap-PCR and RDB, based on invasively sampled amniotic fluid. A non-invasive prenatal diagnosis procedure from maternal plasma fetal DNA was successfully developed based on haplotype analysis. The deduced haplotypes of eight fetuses were identical to the results of invasive prenatal diagnosis procedures, with an accuracy rate of 100%. Taken together, the present study demonstrated the potential for non-invasive prenatal diagnosis of α- and β-thalassemia using NGS and haplotype-assisted analysis.

Prevalence and genetic analysis of thalassemia in neonates in Wuhan area: a national megacity in central China

Background Thalassemia is one of the most common genetic diseases in southern China. Accurate population frequency data regarding the occurrence and distribution of thalassemia is important for designing appropriate prevention strategies of thalassemia. Objective The aim of this study is to reveal the prevalence and the mutation spectrum of thalassemia in neonates in the Wuhan region of central China. Methods About 3796 neonates in Wuhan area of China were analyzed by hematological and genetic analysis. Results About 2174 subjects were genetically diagnosed as thalassemia carriers or patients, including 1415 cases of α-thalassemia (65.89%), 731 cases of β-thalassemia (33.62%), and 28 cases of α-composite β-thalassemia (1.29%). A total of 11 genotypes and 6 gene mutations were identified in α-thalassemia anomalies, with —SEA/deletion (50.72%), -α3 . 7/deletion (36.36%), and -α4 . 2/deletion (7.38%) being the most common α-thalassemia mutations. β-thalassemia anomalies were associated with 17 genotypes and 12 gene mutations; IVS-2-654 mutation was the most common (41.18%), followed by CD41-42 (23.14%), CD17 (14.64%), CD26 (7.32%), and CD27-28 (4.58%) mutations. In addition, 13 genotypes were identified in α-composite β-thalassemia in thalassemia carrier, with the top six genotypes being IVS-2-654/N/—SEA/αα (17.86%), CD17/N/-α3 . 7/αα (17.86%), IVS-2-654/N/-α3 . 7/αα (14.29%), CD41-42/N/—SEA/αα (10.71%), CD71-72/N/-α3 . 7/αα (7.14%), and Cap/N/—SEA/αα (7.14%). Conclusion There was high heterogeneity and extensive spectrum of thalassemia in the neonates in Wuhan populations. The findings will be useful for genetic counseling and prenatal diagnosis of thalassemia in the Wuhan region.

Knowledge of thalassemia and consanguinity: A multicenter hospital based retrospective cohort study from metropolitan city of Karachi, Pakistan.

Objectives: To find the association between consanguinity and frequency of b-thalassemia and to assess the knowledge of parents regarding disease as well as inclination towards premarital carrier screening (PMCS), pre natal diagnosis, pre conception genetic counseling. Study Design: A retrospective cohort study. Setting: Patients with beta thalassemia attending Fatimid Foundation and PNS Shifa Hospital, Karachi. Period: Six Months July – December, 2017. Materials and Methods: Data was collected by pre tested questionnaire which include basic demographic profile, frequency of consanguineous marriages and knowledge regarding disease from parents of children suffering from thalassemia. The study was approved by ethical review committee. Data was analyzed using SPSS version 21. Chi square test was applied. Results: Data was collected from 200 study participants including parents of thalassemia. Males were 52% and 48% were the females. 78.5% were relatives (p=0.001) out of these related, first degree relatives were 61% and 17.5% were distant relatives (p 0.009). Only 25% were aware of genetic counseling, 65% know that thalassemia had genetic mode of transmission (p=0.005), 24% were aware of screening modalities available for thalassemic patients (p=0.001). About 63.55% agreed that premarital screening can prevent thalassemia (p=0.001), majority (83%) of parents were not aware of pre natal diagnosis of thalassemia (p=0.001) more than half of study participants (52%) were still in favor of cousin marriages in future. Conclusion: Thalassemia was found most prevalent among first degree familial relatives. Parents have inadequate knowledge regarding disease. Lack of knowledge and trends consanguineous marriages are strong contributory factor for causation of disease.

Prenatal Diagnosis of Thalassemia

Thalassemia is an individual as well as a community health problem in some countries. It causes a lifelong suffering for the affected individuals. There is no treatment other than supportive, i.e. regular transfusions and removal of iron overload from the body. Only by such continuous and expensive treatment thalassemic patients can-generally achieve nearly normal health, but the health burden of such therapy for a large number of thalassemic patients is unaffordable by the affected communities. Prevention of the births of thalassemic babies is the choice for controlling the thalassemia and has been successful in many countries. For this purpose reliable and time accurate prenatal diagnosis is a conditio sine qua non. Blood fetal sampling is safe and can be done after 16 weeks gestation, amniocentesis after 14 weeks, and even chorionic villi sampling as early as 8 weeks gestation. In vitro globin synthesis analysis applied to the fetal blood sample is very reliable to measure the rate of synthesis of the globin chains that make up the hemoglobin. The-DNA analysis of the fibroblasts obtained by amniocentesis or of the chorionic villus sample is very sensitive and specific for the diagnosis of the genetic disorder in thalassemias. By involving the prenatal diagnosis, the birth of B-homozygous thalassemia has decreased by up to 90%.

Relationship Between Social Determinants of Health and the Thalassemia Prenatal Diagnosis Test in Zahedan, South Eastern Iran

Little is known about the social determinants of health (SDH) of taking the prenatal diagnosis (PND) test as a pivotal strategy to prevent occurrences of β-thalasssemia major (β-TM). This study sought to evaluate the relationship between socio-demographic characteristics of parents and taking the PND test at Zahedan, Iran from 2015 to 2016. The design of the present study was a case-control. Data on socio-demographic characteristics of parents including age, education, job, ethnicity, and family relationships, kind of marriage as well as pre marriage test status and PND test status, were obtained from registered medical records. The relationship between socio-demographic characteristics and taking the PND test was evaluated using binary logistic regression. The study included 256 β-thalassemia (β-thal) carrier couples who were referred to the Zahedan Prenatal Diagnosis Center to take the PND test and 47 β-thal carrier couples who already had a newborn with β-TM and had not taken the PND test. Univariate analysis showed that the higher education level of the father, consanguineous parents, official marriages, pre marriage test and consultation, significantly increased the odds of taking the PND test. The significant relationships were not observed in multivariable analysis, however, pre marriage tests and official marriages can be considered as determinants of taking the PND test with odds ratio (OR) [95% confidence interval (95% CI)] of 14.67 (0.64, 334.93) and 3.41 (0.55, 20.94), respectively. Our results provided evidence in which socio-demographic characteristics of the parents may determine their taking the PND test.

During The Venture of Prenatal Diagnosis of Thalassemia, a vis-à-vis Elucidated Collage of Genetic Polymorphism of West Bengal, India

During The Venture of Prenatal Diagnosis of Thalassemia, a vis-à-vis Elucidated Collage of Genetic Polymorphism of West Bengal, India

Pre-natal diagnosis of thalassaemia in Sri Lanka: A ten year review

Thalassaemia is the commonest monogenic disease in Sri Lanka, affecting over 3500 children and half-a-million thalassaemia carriers. This is a review of 82 amniocenteses performed from 2006 to 2016, in the largest prenatal diagnoses study for thalassaemia carried out in Sri Lanka. Amniocenteses were performed between 11 and 12 weeks of ultrasonically confirmed gestation, on mothers with previous thalassaemia major children pregnant for the second time and nulliparous thalassaemia trait women married to trait partners. The Consultant Radiologist, using local analgesia, under ultrasound cover, performed these as an outpatient procedure, at the Teaching Hospital Kandy & Suwasevana Hospital Kandy. The amniotic fluid was analysed by the team of Senior Geneticists, at the Genetech Molecular Diagnostics and School of Gene Technology, Colombo, via the polymerase-chain-reaction based ARMS (Amplification Refractory Mutation Systems) assay. The genetic results indicated the presence of 21% thalassaemia major foetuses, 53% thalassaemia traits and 26% foetuses without thalassaemia mutations. The predominance of the IVS1-5(G-C) mutation in the Sri Lankan population is exemplified, with a low prevalence of HbE thalassaemia.Impact statementThalassaemia is the commonest monogenic disease in Sri Lanka affecting over 3500 children and half-a-million thalassaemia carriers. Although pre-natal diagnosis by amniocentesis was practised universally for many years, this could not be performed in Sri Lanka as genetic diagnostic facilities were not available until 2005. Therefore, parents with a thalassaemia major child limited their families to one child, by choice or by termination.The results of this study point to a 21% probability of thalassaemia major in the next child, giving the parents a guarded optimism to conceive another child without thalassaemia disease. With siblings being the highest HLA compatibility for Bone Marrow Transplant, that is now being established in Sri Lanka as a permanent cure for thalassaemia, this will bring a ray of hope for these desperate parents to finally cure their previous sick child.Although, 95% of the Sri Lankan mutated genetic sites for thalassaemia are known, more research will be needed to identify the other rare sites. The publication of this paper, with its novelty for pre-natal diagnosis, would encourage clinicians to practice it in other centres and to extend it to families with other genetic disorders.

Prenatal diagnosis of thalassemia in twin pregnancies in mainland China

The aim of this study was to describe our experience with prenatal diagnosis of thalassemia in twin pregnancies at a tertiary referral centre in mainland China. All cases of twin pregnancies at risk of α- or β-thalassemias were followed over an eight-year period. There were 32 twin pregnancies at a mean gestation of 14 weeks (range, 11–21 weeks) at risk of thalassemias, including 19 at risk of α-thalassemia and 13 at risk of β-thalassemia. Chorionicity was determined by ultrasound before prenatal diagnosis. In 19 twin pregnancies at risk of α-thalassemia, there were four where both foetuses were affected, 13 where both foetuses were not affected, and two where one foetus was affected and the other one was not affected. In 13 twin pregnancies at risk of β-thalassemia, there were five where both foetuses were affected, six where both foetuses were not affected, and two where one foetus was affected and the other one was not affected. The pregnancies with two affected foetuses were aborted (including four affected by α-thalassemia and five affected by β-thalassemia), and in pregnancies with one normal twin and one affected twin, the affected foetuses were selectively aborted (including two twins affected by α-thalassemia, and two twins affected by β-thalassemia). Efforts should be taken to reduce the risks of the mother and foetuses in prenatal diagnosis without compromising the precise diagnosis.

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

The aim of the present study was to report the use of analysis of fetal blood in prenatal diagnosis (PND) of β- and α-thalassemia (β- and α-thal), at a Chinese tertiary, maternity center. All cases undergoing invasive testing for PND of thalassemias from 1 January 2010 to 31 December 2014 were included. The main clinical characteristics of these invasive procedures were retrieved from the database software used for analysis. One thousand, nine hundred and six invasive PNDs were carried out for thalassemia, including 904 cases for β-thal and 1002 for α-thal. In the 904 PNDs for β-thal, chorionic villus sampling (CVS) was done in 321 cases and amniocentesis in 583 cases. No fetal blood analysis was used for cases at-risk for β-thal. In the 1002 PNDs for α-thal, CVS was done in 724 cases, amniocentesis in 137 cases and fetal blood analysis in 141 cases. All the 278 cases sampled by amniocentesis or fetal blood analysis were found to be affected by Hb Bart’s (γ4) disease. Currently, fetal blood analysis is considered only in relatively late gestation when Hb Bart’s disease has already been identified by ultrasound in a fetus at-risk for α-thal.