Prenatal Diagnosis Of Thalassemia Research Articles

Prenatal diagnosis of thalassemia

Prenatal diagnosis of thalassemia

Effectiveness of β-thalassemia prenatal diagnosis in Southern Iran: a cohort study.

The aim of this study was to evaluate the effectiveness of prenatal diagnosis (PND) for the prevention of thalassemia in Southern Iran. From 2004 to 2012 1346 couples with β-thalassemia minor were referred to our center. Mutation analyses utilized different methods including polymerase chain reaction-based technique of amplification refractory mutation system (ARMS), Restriction Fragment Length Polymorphism Analysis of PCR-Amplified Fragments (PCR-RFLP) and Gel Electrophoresis and direct sequencing. Haplotype analysis of the β-globin gene cluster was done routinely using the PCR-RFLP technique. Of the 1346 couples, 884 (66%) requested PND. They had a total of 985 pregnancies (954 singleton and 31 twin pregnancies): the 1016 fetuses underwent chorionic villus sampling (CVS). Thalassemia major was diagnosed in 266 cases (26.2%), and termination of pregnancy was requested by the parents in 264 of them (99%). Thalassemia trait was detected in 499 (49.1%) and 251 cases (24.7%) showed no β-thalassemia mutations. There were three misdiagnoses (0.4%) (affected children diagnosed as carriers at PND). A unique pattern of thalassemia mutations was present in the study population, with IVS II-I (G→A), C36-37(-T), IVS I-5(G>C), -25bpdel (252-276), IVS I-110(G>A) and C44 (-C) being present in 62% of cases. The pattern of distribution of thalassemia mutations differs among ethnic groups within the same country.

Diagnosis and prenatal diagnosis to a family of hemoglobin variant with α-thalassemia

Diagnosis and prenatal diagnosis to a family of hemoglobin variant with α-thalassemia. Whole blood cell analysis, hemoglobin analysis by capillary zone electrophoresis (CZE), Gap-PCR, polymerase chain reaction-reverse dot blot (PCR-RDB) assay and DNA sequencing. Hb Zurich Albisrieden with α°-thalassemia lead to severe anemia. The genotype of fetus is also Hb Zurich Albisrieden with α°-thalassemia. Abnormal hemoglobin with α-thalassemia may lead to severe anemia, Prenatal diagnosis of thalassemia has the vital significance for eugenic birth.

Role of genetic counselling in prenatal diagnosis of β-thalassaemia in Pakistan.

To compare the response towards prenatal diagnosis (PND) of b-thalassaemia, in individuals who had not received genetic counselling and a genetically counselled population. Cross-sectional survey. Department of Haematology, Armed Forces Institute of Pathology (AFIP), Rawalpindi, from March 2009 to December 2010. Using non-probability consecutive sampling, a total of 176 individuals having thalassaemic children, were interviewed regarding PND of thalassaemia, by using a structured questionnaire. Forty two individuals were taken as controls as they had received genetic counselling for PND, whereas the remaining 134 were taken as cases. Responses towards PND were compared using chi-square test. Odds ratio was also calculated for subsequent PND utilization. Seventy (52.2%) cases and 42 (100%) controls were aware of the availability of PND in Pakistan. This difference in awareness was statistically significant (p < 0.001). In the controls, 40 (95.3%) individuals were aware of the appropriate timing of the test, in contrast to 52 (39%) cases (p < 0.001). PND was used in subsequent pregnancies by 50 (37.3%) cases and 32 (80%) controls (p < 0.001). The calculated odds ratio for subsequent PND utilization was 5.37. The study reflects a very positive attitude of genetically counselled thalassaemia affected families towards PND. For better utilization of PND, genetic counselling services should be available at all health strata.

Is the Poly A (T>C) Mutation a Causative Factor For Misdiagnosis in Second Trimester Prenatal Diagnosis of β-Thalassemia by Fetal Blood Analysis on High Performance Liquid Chromatography?

We report the problems in diagnosis faced by two families referred for prenatal diagnosis of thalassemia where cordocentesis and fetal blood analysis by high performance liquid chromatography (HPLC) had to be done. The Hb A levels of the fetal blood measured by HPLC on the VARIANT™ Hemoglobin Testing System were 1.2 and 6.7%, respectively, suggestive of a heterozygous β-thalassemia (β-thal) fetus in the first case and a normal fetus in the second case. In one family, one of the parents had a borderline Hb A2 level and in the other, one parent had normal RBC indices. However, DNA sequencing, done later, showed that in the first case the fetus was a compound heterozygote for the IVS-I-5 (G>C) and the polyadenylation signal site [poly A (T>C)] mutation, while in the second case, the fetus was homozygous for the poly A mutation. This emphasizes that characterization of β-thal mutations must be done whenever one of the parents has a borderline Hb A2 level or normal RBC indices, and one should not rely on fetal blood analysis by HPLC for prenatal diagnosis of β-thal so as to avoid misdiagnosis.

Analysis of prenatal diagnosis results of 206 thalassemia families

Objective To summarize the geographical distribution,phenotype and genotype data of 206 thalassemia families underwent prenatal diagnosis to provide information for clinical genetic counseling and avoid the birth of severe thalassemia children. Methods Totally,206 thalassemia families were collected from Southern Medical University Nanfang Hospital from January 2008 to December 2009.Genomic DNA was extracted from peripheral blood,villus,amniotic fluid or cord blood from the couples or the fetuses.Gap-polymerase chain reaction (gap-PCR) and reverse dot blot (RDB) technology were used to detect the common α and β-thalassemia mutations.DNA sequencing was used to detect the rare mutations.Follow-up visit were done half a year after the fetuses were born. Results The 206 thalassemia families came from 12 provinces and areas across China,including Heilongjiang province.Mutations detected in α-thalassemia families included --SEA/,-α3.7/,-α4.2/,αCS α/ and αQS α/,which were all included in the testing kit. While there were 4 kinds of β-thalassemia mutations,Gγ+ (A γδβ)0,-28(A→C),CD54-58(-TATGGGCAACCCT) and CD37(G→A),could not be identified with routine testing kit. The 57 α-thalassemia families consisted of 11(19.3％) severe thalassemia,induding 8 Bart's hydrops syndrome and 3 Hb H disease,26(45.6％) heterozygote and 20(35.1％) normal infants,and the 149 β-thalassemia majors families consisted of 28 (18.8％) severe thalassemia,82(55.0％) heterozygote and 39 (26.2％) normal infants.Among the β-thalassemia heterozygotes,there was one 13-trisomy.Follow-up visit found that babies with Bart ' s hydrops syndrome (n =8),Hb H disease (n =3),β-thalassemia majors (n =28) and β thalassemia heterozygote combined with 13-trisomy(n=1) were aborted. Conclusions Thalassemia was found in some north area other than south of China,which should be paid more attention by clinicians.Gap-PCR and PCR-RDB technology are effective measures for thalassemia prenatal diagnosis in identifying major thalassemia fetuses before their birth,thus reduce the birth rate of thalassemia baby.But missed diagnosis might exist during the screening,so it is necessary to perform DNA sequencing on those patients with positive symptoms and negative common genetic diagnostic results.At the same time,prenatal diagnosis of chromosomal disorders should not be neglected for high-risk families. Key words: Thalassemia; Prenatal diagnosis; Sequence analysis,DNA

Early Prenatal Diagnosis of Thalassemia: The First Report of Experience in Mainland China

In this study, we report our experience with chorionic villus sampling (CVS) for prenatal diagnosis of thalassemia in mainland China. During a 4-year period, 308 pregnant women chose to have CVS for prenatal diagnosis. Chorionic villus sampling was successful in all cases, and post-CVS abortion was seen in only two cases (0.6%). DNA diagnosis was correctly done in 307 (99.7%) prenatal samples but maternal contamination was found in one (0.3%) subject. In total, 77 pregnancies were found with an affected fetus, and all of the affected pregnancies were terminated within 1 week after the CVS procedure. Our experience indicates that CVS is a feasible and effective technique for prenatal diagnosis of thalassemia.

Fetal blood analysis is not a primary method in prenatal diagnosis of thalassemia

Fetal blood analysis is not a primary method in prenatal diagnosis of thalassemia

DNA Diagnostics by Surface-Bound Melt-Curve Reactions

Melting-curve procedures track DNA denaturation in real time and so provide an effective way of assessing sequence variants. Dynamic allele-specific hybridization (DASH) is one such method, based on fluorescence, which uses heat to denature a single allele-specific probe away from one strand of a polymerase chain reaction product attached to a solid support. DASH is a proven system for research genotyping, but here we evaluate it for DNA diagnostics under two scenarios. First, for mutation scanning (resequencing), a human genomic sequence of 97 bp was interrogated with 15 probes tiled with 12-base overlaps, providing up to fourfold redundancy per base. This test sequence spanned three high-frequency single nucleotide polymorphisms, all of which were correctly revealed in 16 individuals. Second, to score multiple different mutations in parallel, 18 alterations in the gyrA gene of Salmonella were assessed in 62 strains by using wild-type- and mutation-specific probes. Both experiments were performed in a blinded manner, and all results were confirmed by sequencing. All DNA variants were unambiguously resolved in every sample, with no false-positive or false-negative signals across all of the investigations. In conclusion, DASH performs accurately and robustly when applied to DNA diagnostic challenges, including mutation scoring and mutation scanning.

THE THALASSEMIA SYNDROMES: MOLECULAR CHARACTERIZATION IN THE SPANISH POPULATION

This work compiles the results of our research on α- and β-thalassemias, and includes a literature review of the molecular genetics of α- and β-thalassemias in Spain. We studied 1,564 subjects with thalassemia (294 with β-thalassemia and 1,264 with α-thalassemia) by molecular biology techniques. In relation to β-thalassemia, a total of 15 different mutations were characterized in a study of 308 chromosomes belonging to 294 unrelated subjects. Eleven were homozygotes (22 alleles), three compound heterozygotes (6 alleles), and the remaining 280 were heterozygotes (280 alleles). A total of 86.6% of the alleles identified can be grouped into five different mutations [IVS-I-1 (G → A), IVS-I-6 (T → C), IVS-I-110 (G → A), codon 39 (C → T), codons 8/9 (+G)]. In 14 subjects (4.5%), all heterozygotes, it was not possible to identify the alteration responsible for the β-thalassemia.For α-thalassemia, 911 subjects showed heterozygous α+-thalassemia (872 with −3.7 kb; 14 with −4.2 kb; two with the deletion of 3.5 kb of DNA, and 23 with nondeletional α-thalassemia). Two hundred and thirty-three subjects had homozygous α+-thalassemia (223 for –α−3.7/–α−3.7); one for –α−4.2/–α−4.2; six for –α−3.7/–α−4.2; one for –α−3.5/–α−3.7; one for ααNco/ααNco; one for αHphα/αHphα). One hundred patients presented with heterozygous α0-thalassemia (18 of whom were progenitors of patients with Hb H disease). The α0 determinant was found in 20 patients with Hb H disease associated with –α−3.7. From the DNA analysis were identified the ––MED, ––SEA, ––SPAN deletions and the ––CAL, ––CANT, and ––MA mutations; in three cases, a break that affects the distal portion of the short arm of chromosome 16; one of these was associated with the ATR-16 (α-thal with mental retardation) syndrome. Triplication of the α genes (ααα−3.7/αα) was found in 25 subjects, 16 of whom were associated with a heterozygous β-thalassemia. Only one patient was homozygous for the triplication of α genes (ααα−3.7/ααα−3.7) that was associated with a heterozygous β-thalassemia.In the Mediterranean region preventive programs for thalassemia, based on the detection of heterozygote carriers and genetic advice, are not sufficient to reduce the incidence of newborns with major thalassemia. Prenatal diagnosis of thalassemias has given a new dimension to the prevention of these, but in order to implement this, a knowledge of the mutations and the incidence of these, is essential. This study, therefore, aims to give a general picture of the molecular genetics of thalassemia and its geographical distribution in our area.

Antenatal screening and prenatal diagnosis of thalassaemia

Antenatal screening and prenatal diagnosis of thalassaemia

Antenatal screening and prenatal diagnosis of thalassaemia

Antenatal screening and prenatal diagnosis of thalassaemia

Antenatal screening and prenatal diagnosis of thalassaemia

Antenatal screening and prenatal diagnosis of thalassaemia

Antenatal screening and prenatal diagnosis of thalassaemia: an update.

Antenatal screening and prenatal diagnosis of thalassaemia: an update.

Prenatal diagnosis of thalassemia in the Chinese.

There is a high prevalence of thalassemia in the Taiwan area. Prenatal diagnosis of severe forms of thalassemia is important for the prevention of this disease. We performed prenatal diagnosis in 167 cases, of which 59 cases were diagnosed by chorionic villi biopsy, 91 cases by amniotic fluid analysis, and 17 cases by cord blood analysis. Hb Bart's hydrops was detected by amplifying the break junction area of the alpha-thalassemia-1 Southeast Asia (SEA)-type gene, and beta-thalassemia major was detected by using naturally occurring restriction sites and the amplified created restriction sites (ACRS) method. Screening for hemoglobin (Hb) Bart's hydrops revealed 26 cases of Hb Bart's hydrops, 67 cases of alpha-thalassemia-1 (including 6 Hb Bart's hydrops falsely diagnosed as alpha-thalassemia-1 from chorionic villi samples), and 38 normal cases. Screening for beta-thalassemia major revealed 8 cases of beta-thalassemia major, 17 cases of beta-thalassemia minor, and 11 normal cases. In cases of alpha-thalassemia, maternal tissue contamination in the chorionic villi samples occurred in the diagnosis of the carrier state and further amniotic fluid analysis will be necessary. There were no any false-positive or false-negative results in beta-thalassemia major screening. We conclude that prenatal diagnosis is a reliable and accurate screening method for thalassemia and may be valuable in other areas of high prevalence for thalassemia in Southeast Asia and in Southern China.

Prenatal diagnosis of thalassemia and hemoglobinopathies in Switzerland

During a 10-month period, 10 couples originating from Africa (3), the tropics (1) and the thalassemia-belt region (6), living in Switzerland, requested prenatal diagnosis of hemoglobinopathies. Hb SS (twice), Hb Bart's (Hydrops fetalis) and beta-thalassemia major were diagnosed either by gene mapping or by direct detection of the mutations in DNA amplified by the PCR procedure. Whenever it was possible to obtain fetal blood or tissue, diagnosis was confirmed. In one Vietnamese man, concomitant existence of alpha-thal 1 with beta-thalassemia resulted in an unusually high Hb level because of balanced alpha and beta globin synthesis. The 10 couples examined originated from 7 different countries and presented at least 7 different Hb pathologies. This variety of pathologies represents the main difficulty for prenatal diagnosis of hemoglobinopathies in a non-endemic country. A diagnostic approach to overcome this problem is developed.

Prenatal Diagnosis of Thalassemia in South Chinaa

Prenatal Diagnosis of Thalassemia in South China^a

Prenatal Diagnosis of Thalassemia and of the Sickle Cell Syndromes in Greecea

Prenatal Diagnosis of Thalassemia and of the Sickle Cell Syndromes in Greece^a

Prenatal diagnosis of thalassemia: the viewpoint of patients.

Twenty-eight young people with thalassemia major expressed their opinion about prenatal diagnosis. All of them stated that they intended to marry and have children; thirteen of them (46 per cent) said that they would have also accepted a thalassemic carrier as a partner and that if married to a carrier they would have undergone prenatal diagnosis and selective abortion. All but one refused the prospect of an affected child. When asked if they would have preferred that before their birth their parents had undergone prenatal diagnosis and abortion, 19 patients (68 per cent) gave an affirmative answer. These results clearly indicate that even people affected by thalassemia major, who are the potential victims of prenatal diagnosis and selective abortion, largely accept prenatal diagnosis as a means of preventing their disease.

Prenatal diagnosis of thalassemia: experiences at the Shanghai Children's Hospital.

Using DNA dot-blot hybridization, restriction endonuclease gene mapping with oligonucleotide probes, restriction fragment length polymorphism linkage analysis, and hybridization, prenatal diagnosis was performed for 32 pregnancies at risk for alpha-thalassemia and for 10 pregnancies at risk for beta-thalassemia. The DNA samples were prepared from chorion villi or amniotic fluid cells.